- A Simple Synthesis of trans-Δ9-Isoambrettolide, Dihydroambrettolide, and Methyl 16-Acetoxy-9-hexadecenoate
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Δ9-Isoambrettolide (2) and methyl 16-acetoxy-9-hexadecenoate (3) are prepared from aleuritic acid and dimethylformamide dialkyl acetals by a one-pot reaction.Catalytic hydrogenation of products 2 and 3 affords dihydroambrettolide (6) and methyl 16-acetoxyhexadecanoate (7), respectively.
- Villemin, Didier
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- Lactonization of ω-Hydroxy Esters over Hydrous Zirconium(IV) Oxide
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The lactonization of ω-hydroxy esters was carried out by catalysis with hydrous zirconium(IV) oxide.In the flow reaction system, ω-hydroxy esters were efficiently converted to give the corresponding lactones.In particular, it is noteworthy that heptanolide is obtained in good yield.In addition, it is possible to produce a large quantity of lactones in this catalyst system.
- Kuno, Hideyuki,Shibagaki, Makoto,Takahashi, Kyoko,Honda, Ichiro,Matsushita, Hajime
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- MACROCYCLIC LACTONES VIA BIOCATALYSIS IN NON-AQUEOUS MEDIA
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The enantiospecificity of lipase-catalyzed lactonization of chiral (w-1)-hydroxy acids to form diolides in non-aqueous medium was investigated.
- Zhi-wei, Guo,Ngooi, T. K.,Scilimati, A.,Fuelling, Gerd,Sih, Charles J.
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- Effect of micelles on cyclization reactions: The use of N-hexadecyl-2- chloropyridinium iodide as an amphiphilic carboxyl-activating agent in lactonization and lactamization
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Lactonization and lactamization with a novel carboxyl-activating agent, N- hexadecyl-2-chloropyridinium iodide (C16PyCl,I), were investigated. The organization of this agent in micelles in the reaction medium facilitates cyclization giving rise to a micellar effect. Under these conditions, the corresponding lactam is produced from the ω-amino acid 12-aminododecanoic acid in good yield (double that obtained with the Mukaiyama reagent, N- methyl-2-chloropyridinium iodide C1PyCl,I). On the other hand, the yield of lactone from 16-hydroxyhexadecanoic acid was the same with either carboxyl- activating agent. These results were accounted for in terms of substrate- dependent micellar effects. Because of solubility effects, the ω-amino acids and ω-hydroxy acids are not localized in comparable ways vis a vis the interface and, thus, have different reactivities. Moreover, hydrolysis of the reagents, C16PyCl,I and C1PyCl,I, was also detected. The interference of this reaction with the cyclization process was also found to depend on a micellar effect with C16PyCl,I that is not observed with C1PyCl,I.
- Rico,Halvorsen,Dubrule,Lattes
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- DMEAD: a new dialkyl azodicarboxylate for the Mitsunobu reaction
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Di-2-methoxyethyl azodicarboxylate (DMEAD) is prepared in 65% yield in two steps as a crystalline solid. Use of DMEAD in the Mitsunobu reaction of a variety of alcohols with pronucleophiles results in good yields of the products under sufficient stereospecificity of inversion, as conventional diisopropyl azodicarboxylate (DIAD) does. Isolation of the product is, however, much easier with DMEAD than that with DIAD, because the hydrazine produced from DMEAD is highly hydrophilic and is completely separable by a simple extraction into neutral water. Purification of the organic layer, after separation of the other by-product, triphenylphosphane oxide, by filtration, easily provides high purity of the product in a good yield. Concentration of the water layer yields the hydrazine, which can be reused for the preparation of DMEAD. One-step removal of the two by-products by the aqueous extraction was also possible when trimethylphosphane and DMEAD were employed.
- Hagiya, Kazutake,Muramoto, Natsuko,Misaki, Tomonori,Sugimura, Takashi
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- Flow Chemistry under Extreme Conditions: Synthesis of Macrocycles with Musklike Olfactoric Properties
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Starting from small cyclic ketones, continuous flow synthesis is used to produce medium-sized rings and macrocycles that are relevant for the fragrance industry. Triperoxides are important intermediates in this process and are pyrolyzed at temperatures above 250 °C. The synthesis is carried out in two continuously operated flow reactors connected by a membrane-operated separator. The practicality of flow chemistry is impressively demonstrated in this work by the use of hazardous reagent mixtures (30% H2O2, 65% HNO3) and the pyrolysis of no less problematic peroxides. All new macrocycles were tested for their olfactory properties in relation to musk.
- Seemann, Alexandra,Panten, Johannes,Kirschning, Andreas
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supporting information
p. 13924 - 13933
(2021/05/29)
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- Macrolactonization Reactions Driven by a Pentafluorobenzoyl Group**
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Macrolactones constitute a privileged class of natural and synthetic products with a broad range of applications in the fine chemicals and pharmaceutical industry. Despite all the progress made towards their synthesis, notably from seco-acids, a macrolactonization promoter system that is effective, selective, flexible, readily available, and, insofar as possible, compatible with manifold functional groups is still lacking. Herein, we describe a strategy that relies on the formation of a mixed anhydride incorporating a pentafluorophenyl group which, due to its high electronic activation enables a convenient access to macrolactones, macrodiolides and esters with a broad versatility. Kinetic studies and DFT computations were performed to rationalize the reactivity of the pentafluorophenyl group in macrolactonization reactions.
- Ciofini, Ilaria,Force, Guillaume,Leb?uf, David,Mayer, Robert J.,Perfetto, Anna
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supporting information
p. 19843 - 19851
(2021/08/13)
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- Highly selective macrocyclic ring-closing metathesis of terminal olefins in non-chlorinated solvents at low dilution
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A set of new ruthenium-indenylidene complexes bearing two unsymmetrical unsaturated N-cycloalkyl-NHC ligands were synthesized. These catalysts proved to be highly selective in the macrocyclic ring-closing metathesis performed in non-chlorinated solvents at low dilution (0.01 M). Without the requirement of benzoquinone derivatives to prevent the isomerisation side reactions, this environmentally friendly catalytic process promoted the synthesis of macrocyclic odorant molecules with remarkable >99% purity.
- Dumas, Adrien,Colombel-Rouen, Sophie,Curbet, Idriss,Forcher, Gwénael,Tripoteau, Fabien,Caijo, Frédéric,Queval, Pierre,Rouen, Mathieu,Baslé, Olivier,Mauduit, Marc
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p. 436 - 443
(2019/01/28)
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- A General Catalytic Method for Highly Cost- and Atom-Efficient Nucleophilic Substitutions
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A general formamide-catalyzed protocol for the efficient transformation of alcohols into alkyl chlorides, which is promoted by substoichiometric amounts (down to 34 mol %) of inexpensive trichlorotriazine (TCT), is introduced. This is the first example of a TCT-mediated dihydroxychlorination of an OH-containing substrate (e.g., alcohols and carboxylic acids) in which all three chlorine atoms of TCT are transferred to the starting material. The consequently enhanced atom economy facilitates a significantly improved waste balance (E-factors down to 4), cost efficiency, and scalability (>50 g). Furthermore, the current procedure is distinguished by high levels of functional-group compatibility and stereoselectivity, as only weakly acidic cyanuric acid is released as exclusive byproduct. Finally, a one-pot protocol for the preparation of amines, azides, ethers, and sulfides enabled the synthesis of the drug rivastigmine with twofold SN2 inversion, which demonstrates the high practical value of the presented method.
- Huy, Peter H.,Filbrich, Isabel
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supporting information
p. 7410 - 7416
(2018/04/30)
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- Polycyclic ketone monooxygenase from the thermophilic fungus Thermothelomyces thermophila: A structurally distinct biocatalyst for bulky substrates
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Regio- and stereoselective Baeyer-Villiger oxidations are difficult to achieve by classical chemical means, particularly when large, functionalized molecules are to be converted. Biocatalysis using flavin-containing Baeyer-Villiger monooxygenases (BVMOs) is a wellestablished tool to address these challenges, but known BVMOs have shortcomings in either stability or substrate selectivity. We characterized a novel BVMO from the thermophilic fungus Thermothelomyces thermophila, determined its three-dimensional structure, and demonstrated its use as a promising biocatalyst. This fungal enzyme displays excellent enantioselectivity, acts on various ketones, and is particularly active on polycyclic molecules. Most notably we observed that the enzyme can perform oxidations on both the A and D ring when converting steroids. These functional properties can be linked to unique structural features, which identify enzymes acting on bulky substrates as a distinct subgroup of the BVMO class.
- Fürst, Maximilian J.L.J.,Savino, Simone,Dudek, Hanna M.,Castellanos, J. Rúben Gómez,De Souza, Cora Gutiérrez,Rovida, Stefano,Fraaije, Marco W.,Mattevi, Andrea
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supporting information
p. 627 - 630
(2017/05/15)
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- METHOD FOR PRODUCING OMEGA-HYDROXY FATTY ACID ESTER AND PRECURSOR COMPOUND THEREOF
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Provided is a method for producing a compound represented by Formula (III) while the production of by-products due to, for example, dimerization of a raw material or isomerization of a double bond position is suppressed. The method is a method for producing omega-hydroxy fatty acid ester and a precursor compound thereof of Formula (III), in which an alcohol derivative and a carboxylic acid derivative are subjected to a metathesis reaction in the presence of a catalyst to obtain a compound of Formula (III), wherein the alcohol derivative is at least one selected from the group consisting of a compound of Formula (VI) and a compound of Formula (I), and the carboxylic acid derivative is at least one selected from the group consisting of a compound of Formula (VII) and a compound of Formula (II), wherein the case where the alcohol derivative is formed of a compound of Formula (I) and the carboxylic acid derivative is formed of a compound of Formula (II) is excluded,
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Paragraph 0125
(2016/07/27)
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- METHOD FOR MANUFACTURING ALCOHOL BY HYDROGENATION OF CARBOXYLIC ACID COMPOUND AND ESTER COMPOUND
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PROBLEM TO BE SOLVED: To provide a method for obtaining alcohol by hydrogenation of carboxylic acid compound efficiently by using a homogeneous system catalyst, especially a method for obtaining alcohol by hydrogenation of various carboxylic acid compound and ester compound by the homogeneous system catalyst efficiently even under alleviation condition. SOLUTION: A carboxylic acid compound and/or an ester compound is hydrogenated in a presence of a rhenium complex represented by ReXmYnZp, where X is a halogen atom, Y is same or different and each a ligand containing one or more phosphorus atom, Z is a ligand other than X and Y, m is an integer of 1 to 6, p is an integer of 0 to 2 and the sum of m, n and p is an integer of 2 to 6, and a specific alkali metal salt. COPYRIGHT: (C)2015,JPOandINPIT
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Paragraph 0117; 0118; 0127; 0129; 0130
(2016/10/10)
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- Chemoenzymatic preparation of musky macrolactones
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Abstract A chemoenzymatic approach to some musk macrolactones has been explored by the optimization of macrolactonization catalyzed by Candida antarctica lipase B (Novozym 435). This fast and high yield optimized methodology represents a large improvement to previously reported results. The methodology was applied to the preparation of 16-hexadecanolide, exaltolide, ambrettolide and (15R)-15-hexadecanolide.
- Fortunati, Tancredi,D'Acunto, Mariantonietta,Caruso, Tonino,Spinella, Aldo
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p. 2357 - 2362
(2015/03/30)
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- Direct macrolactonization of seco acids via hafnium(IV) catalysis
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Efficient direct macrolactonization of seco acids can be catalyzed by Hf(OTf)4 in high yields, forming water as the sole byproduct. The Hf(OTf)4 catalyst possesses unique reactivity characteristics relative to other Lewis acids, as it promotes macrolactonization over hydrolysis even in the presence of excess water. In addition to forming a variety of macrolactones and benzolactones (55-90%), intermolecular direct esterifications of carboxylic acids and alcohols were also possible and demonstrated compatibility with common carbamate, silyl ether, alkoxymethyl ether, and acetal protecting groups. All of the macrolactonization and esterification processes developed are operationally simple, "one-pot" reactions that exploit a commercially available catalyst without the need for slow addition or azeotropic techniques.
- De Léséleuc, Mylene,Collins, Shawn K.
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p. 1462 - 1467
(2015/03/14)
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- A novel aromatic carbocation-based coupling reagent for esterification and amidation reactions
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A novel tropylium-based coupling reagent has been developed to facilitate the synthesis of a series of esters, amides, lactones and peptides under mild reaction conditions. Remarkably, this reagent can be used in catalytic amounts in conjunction with a sacrificial reagent, offering a new and efficient method for nucleophilic coupling reactions of carboxylic acids.
- Nguyen, Thanh V.,Lyons, Demelza J.M.
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supporting information
p. 3131 - 3134
(2015/06/17)
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- Recyclable hypervalent iodine(III) reagent iodosodilactone as an efficient coupling reagent for direct esterification, amidation, and peptide coupling
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A hypervalent iodine(III) reagent plays a novel role as an efficient coupling reagent to promote the direct condensation between carboxylic acids and alcohols or amines to provide esters, macrocyclic lactones, amides, as well as peptides without racemization. The regeneration of iodosodilactone (1) can also be readily achieved. The intermediate acyloxyphosphonium ion C from the activation of a carboxylic acid is thought to be involved in the present esterification reaction.
- Tian, Jun,Gao, Wen-Chao,Zhou, Dong-Mei,Zhang, Chi
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supporting information; experimental part
p. 3020 - 3023
(2012/08/07)
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- Highly efficient macrolactonization of ω-hydroxy acids using benzotriazole esters: Synthesis of Sansalvamide A
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A facile and mild macrolactonization reaction of ω-hydroxy acids was developed based on the transesterification of benzotriazole esters. Treatment of ω-hydroxy acids with 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) and 1-hydroxy benzotriazole (HOBT) in chloroform provided macrolactones in excellent yields. The reactions were performed under basic, neutral and acidic conditions using N,N-dimethylaminopyridine (DMAP), tetrabutylammonium tetrafluoroborate (TBABF4) and BF3·Et2O, respectively. A calcined hydrotalcite was also used instead of DMAP. Finally, to test the scope of the protocol in the synthesis of biologically relevant macrolactones, the total synthesis of Sansalvamide A was carried out.
- Morales-Serna, Jose Antonio,Sanchez, Ericka,Velazquez, Ricardo,Bernal, Jorge,Garcia-Rios, Erendira,Gavino, Ruben,Negron-Silva, Guillermo,Cardenas, Jorge
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experimental part
p. 4940 - 4948
(2010/11/24)
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- A new method for the lactonization of ω-hydroxy carboxylic acids with Di-2-thienyl carbonate by the promotion of DMAP and iodine
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Successive reactions of ω-hydroxycarboxylic acids with an equimolar amount of di-2-thienyl carbonate (2-DTC) in the presence of a catalytic amount of 4-(dimethylamino)pyridine (DMAP) followed by an addition of 2-4 equimolar amounts of iodine afforded the corresponding lactones in good to high yields. Copyright
- Oohashi, Yoshiaki,Fukumoto, Kentarou,Mukaiyama, Teruaki
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- A new method for the synthesis of carboxylic esters and lactones with di-2-thienyl carbonate (2-DTC) by the promotion of DMAP and iodine
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The esterification of carboxylic acids with alcohols by using di-2-thienyl carbonate (2-DTC) in the presence of a catalytic amount of 4-(dimethylamino) pyridine (DMAP) proceeded smoothly to afford the corresponding esters in good-to-high yields along with 2(5H)-thiophenone. This esterification was accelerated by the addition of an equimolar amount of iodine to afford the esters in higher yields within a shorter reaction time. Further, cyclization of ω-hydroxycarboxylic acids with an equimolar amount of 2-DTC in the presence of a catalytic amount of DMAP, followed by the addition of 1-4 equimolar amounts of iodine, afforded the corresponding lactones in good-to-high yields under mild conditions. This method was successfully employed in the synthesis of erythro-aleuritic acid lactone.
- Oohashi, Yoshiaki,Fukumoto, Kentarou,Mukaiyama, Teruaki
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p. 1508 - 1519
(2007/10/03)
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- Efficient method for the lactonization of ω-hydroxycarboxylic acids with di-2-thienyl carbonate by the promotion of catalytic amounts of DMAP and Hf(OTf)4
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An efficient method for the synthesis of macrolides from ω-hydroxycarboxylic acids is established by using an equimolar amount of di-2-thienyl carbonate (2-DTC) and catalytic amounts of 4-(dimethylamino) pyridine (DMAP) and group 4 metal triflates such as hafnium(IV) trifluoromethanesulfonate (Hf(OTf)4). Copyright
- Oohashi, Yoshiaki,Fukumoto, Kentarou,Mukaiyama, Teruaki
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p. 710 - 711
(2007/10/03)
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- An effective method for the synthesis of carboxylic esters and lactones using substituted benzoic anhydrides with Lewis acid catalysts
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An efficient mixed-anhydride method for the synthesis of carboxylic esters and lactones using benzoic anhydride having electron withdrawing substituent(s) is developed by the promotion of Lewis acid catalysts. In the presence of a catalytic amount of TiCl2(ClO4)2, various carboxylic esters are prepared in high yields through the formation of the corresponding mixed-anhydrides from 3,5-bis(trifluoromethyl)benzoic anhydride and carboxylic acids. The combined catalyst consisting of TiCl 2(ClO4)2 together with chlorotrimethylsilane functions as an effective catalyst for the synthesis of carboxylic esters from free carboxylic acids and alcohols with 4-(trifluoromethyl)benzoic anhydride. Various macrolactones are prepared from the free ω-hydroxycarboxylic acids by the combined use of 4-(trifluoromethyl)benzoic anhydride and titanium(IV) catalysts together with chlorotrimethylsilane under mild reaction conditions. The lactonization of trimethylsilyl ω-(trimethylsiloxy) carboxylates using 4-(trifluoromethyl)benzoic anhydride is also promoted at room temperature in the presence of a catalytic amount of TiCl 2(ClO4)2. An 8-membered ring lactone, a synthetic intermediate of cephalosporolide D, is successfully synthesized according to this mixed-anhydride method using 4-(trifluoromethyl)benzoic anhydride by the promotion of a catalytic amount of Hf(OTf)4.
- Shiina, Isamu
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p. 1587 - 1599
(2007/10/03)
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- An Effective Use of Benzoic Anhydride and Its Derivatives for the Synthesis of Carboxylic Esters and Lactones: A Powerful and Convenient Mixed Anhydride Method Promoted by Basic Catalysts
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Various carboxylic esters are obtained at room temperature in excellent yields with high chemoselectivities from nearly equimolar amounts of carboxylic acids and alcohols using 2-methyl-6-nitrobenzoic anhydride with triethylamine by the promotion of a basic catalyst such as 4-(dimethylamino)pyridine. A variety of lactones are also prepared in high yields at room temperature from the corresponding ω-hydroxycarboxylic acids with use of 2-methyl-6-nitrobenzoic anhydride in the presence of 4-(dimethylamino)pyridine. A similar reaction occurs with triethylamine when using a catalytic amount of 4-(dimethylamino)pyridine 1-oxide as an effective promoter for the intramolecular condensation reaction. These methods are successfully applied to the synthesis of erythro-aleuritic acid lactone and an eight-membered-ring lactone moiety of octalactins A and B. The efficiency of the cyclizations is compared to those of other reported lactonizations.
- Shiina, Isamu,Kubota, Mari,Oshiumi, Hiromi,Hashizume, Minako
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p. 1822 - 1830
(2007/10/03)
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- A new method for the polymer-supported synthesis of cyclic oligoesters for potential applications in macrocyclic lactone synthesis and combinatorial chemistry
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Attachment of ω-hydroxyalkanecarboxylic acids to Merrifield beads followed by treatment with a catalytic amount of di-n-butyltin oxide in chlorobenzene at 133 °C for 4-18 h brought about the formation of the corresponding cyclic oligomers (COs) as the mai
- Ruddick, Clare L.,Hodge, Philip,Cook, Anthony,McRiner, Andrew J.
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p. 629 - 637
(2007/10/03)
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- A novel and efficient macrolactonization of ω-hydroxycarboxylic acids using 2-methyl-6-nitrobenzoic anhydride (MNBA)
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A variety of lactones were prepared in high yields at room temperature from the corresponding ω-hydroxycarboxylic acids using 2-methyl-6-nitrobenzoic anhydride in the presence of 4-(dimethylamino)pyridine. A similar reaction also occurs with triethylamine when using a catalytic amount of 4-(dimethylamino)pyridine 1-oxide as an effective promoter for the intramolecular condensation reaction. These methods were successfully applied to the synthesis of erythro-aleuritic acid lactone and the efficiency of the cyclizations is compared to those of other reported mixed anhydride methods.
- Shiina, Isamu,Kubota, Mari,Ibuka, Ryoutarou
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p. 7535 - 7539
(2007/10/03)
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- Macrolactonization of hydroxy acids using a polymer bound carbodiimide
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An efficient macrolactonization procedure using a polymer bound carbodiimide is described. The procedure uses the polymer supported reagent as a replacement for dicyclohexylcarbodiimide and thus considerably simplifies the workup for such reactions. Partitioning between macrolactone and diolide is shown to depend upon the equivalents of reagent used in cases for which lactonization is difficult. (C) 2000 Published by Elsevier Science Ltd.
- Keck,Sanchez,Wager
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p. 8673 - 8676
(2007/10/03)
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- Zeolite-catalyzed macrolactonization of ω-hydroxyalkanoic acids in a highly concentrated solution
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Lactonization of 15-hydroxypentadecanoic acid to 15-pentadecanolide on dealuminated HY zeolite was successfully performed in a concentrated toluene solution (0.2 M). Addition of a bulky organic base to the reaction system suppressed the lactonization. It was concluded that the lactonization was promoted at specific acid sites on the external surface of the zeolite.
- Ookoshi, Tooru,Onaka, Makoto
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p. 293 - 296
(2007/10/03)
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- Scandium trifluoromethanesulfonate as an extremely active Lewis acid catalyst in acylation of alcohols with acid anhydrides and mixed anhydrides
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Scandium trifluoromethanesulfonate (triflate), which is commercially available, is a practical and useful Lewis acid catalyst for acylation of alcohols with acid anhydrides or the esterification of alcohols by carboxylic acids in the presence of p-nitrobenzoic anhydrides. The remarkably high catalytic activity of scandium triflate can be used for assisting the acylation by acid anhydrides of not only primary alcohols but also sterically-hindered secondary or tertiary alcohols. The method presented is especially effective for selective macrolactonization of ω-hydroxy carboxylic acids.
- Ishihara, Kazuaki,Kubota, Manabu,Kurihara, Hideki,Yamamoto, Hisashi
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p. 4560 - 4567
(2007/10/03)
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- A Novel Method for the Preparation of Macrolides from ω-Hydroxycarboxylic Acids
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An efficient method for the synthesis of macrolides directly from ω-hydroxycarboxylic acids is established by using 4-(trifluoromethyl)benzoic anhydride and a catalytic amount of active titanium(IV) salts together with chlorotrimethylsilane under mild conditions.
- Shiina, Isamu,Mukaiyama, Teruaki
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p. 677 - 680
(2007/10/02)
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- Tin(IV)-catalyzed lactonization of ω-hydroxy trifluoroethyl esters
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1,1,1-Trifluoroethyl esters of ω-hydroxycarboxylic acids were prepared and their conversion to macrocyclic lactones, including ricinelaidic lactone, was studied in the presence of catalytic quantities of tin(IV) reagents; a mechanism involving exchange of alkoxytrialkyltin species is proposed.
- White,Green,Fleming
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p. 3515 - 3518
(2007/10/02)
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- Use of water-in-oil microemulsions and gelatin-containing microemulsion-based gels for lipase-catalysed ester synthesis in organic solvents
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Chromobacterium viscosum (CV) lipase and lipoprotein lipase ex Pseudomonas have been solubilised in AOT water-in-oil microemulsions at two different R-values, and used to catalyse the lactonisation of 16-hydroxyhexadecanoic acid at 40 deg C.CV lipase has also been immobilised in gelatin-containing microemulsion-based gels (MBGs) with retention of catalytic activity.These lipase-containing MBGs prove to be novel solid-phase catalysts for use in apolar organic solvents.MBGs do not dissolve in their parent nor, oil, when pelletted, do they self-associate in the organicsolvent in which they are placed in contact.CV lipase-containing MBGs have been used to synthesise on a preparative scale, a variety of different esters under mild conditions and both regio- and stereoselective syntheses have been demonstrated.Lipase-containing MBGs have also been shown to effectively catalyse esterifications at temperatures as low as -20 deg C.
- Rees, G D,Jenta, T R J,Nascimento, M G,Catauro, M,Robinson, B H,et al.
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- Regioselective Conversion of Nonactivated CH Bonds, VI - Selective ω- to (ω-2)-Chlorination of Fatty Acids by Way of Adsorption on Alumina
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Fatty acids 4-7 can be chlorinated with high selectivity in the (ω-2)- to ω-position.For that purpose the acid is adsorbed on alumina and allowed to react with gaseous chlorine or t-BuOCl at 20 and -35 deg C.The resulting chloroalkanoic acids 10-13 can be converted into macrocyclic lactones 14-17 by treatment with DBU. Key Words: Fatty acids / Chlorination, selective / Lactones
- Hinkamp, Ludger,Schaefer, Hans J.,Wippich, Barbara,Luftmann, Heinrich
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p. 559 - 564
(2007/10/02)
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- LIPASE CATALYZED SYNTHESIS OF MACROCYCLIC LACTONES IN ORGANIC SOLVENTS
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A new method for the preparation of macrocyclic lactones from ω-hydroxyacid methyl esters is described.The approach utilizes intramolecular transesterification catalyzed by lipase in organic solvents.The procedure is also applicable to the synthesis of asymmetric lactones.
- Makita, Atushi,Nihira, Takuya,Yamada, Yasuhiro
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p. 805 - 808
(2007/10/02)
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- S,S'-Bis(1-phenyl-1H-tetrazol-5-yl) Dithiocarbonate: A New Esterification Reagent
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S,S'-Bis(1-phenyl-1H-tetrazol-5-yl) dithiocarbonate is a useful reagent for the esterification of carboxylic acids with alcohols, including lactonization.The reagent is conveniently prepared in good yield from 1-phenyl-5-thioxo-4,5-dihydro-1H-tetrazole and trichloromethyl chloroformate (trichloromethyl carbonochloridate) in ethyl acetate in the presence of triethylamine.Its structure was confirmed by (13)C-NMR spectrometry and single-crystal X-ray analysis.
- Takeda, Kazuyoshi,Tsuboyama, Kanoko,Takayanagi, Hiroaki,Ogura, Haruo
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p. 560 - 562
(2007/10/02)
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- A Novel Template Effect of Distannoxane in Macrolactonization of ο-Hydroxy Carboxylic Acids
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A novel template effect of 1,3-disubstituted tetrabutyldistannoxanes in macrolactonization of ο-hydroxy carboxylic acids has been disclosed.
- Otera, Junzo,Yano, Toru,Himeno, Yasuyuki,Nozaki, Hitosi
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p. 4501 - 4504
(2007/10/02)
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- A CONVENIENT METHOD FOR THE PREPARATION OF MACROLIDES FROM TRIMETHYLSILYL ω-TRIMETHYLSILYLOXYCARBOXYLATES
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Several macrolides were readily prepared from trimethylsilyl ω-trimethylsilyloxycarboxylates by the use of dipropylboryl trifluoromethanesulfonate (triflate) as a catalyst in good yields.
- Taniguchi, Nagahiro,Kinoshita, Hideki,Inomata, Katsuhiko,Kotake, Hiroshi
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p. 1347 - 1348
(2007/10/02)
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- A New and Effective Synthetic Method for the Preparation of the Esters, Peptides, and Lactones Using 3-(5-Nitro-2-oxo-1,2-dihydro-1-pyridyl)-1,2-benzisothiazole 1,1-Dioxide. Synthesis of (+/-)-E-Dodecen-11-olide, Recifeiolide
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3-(5-nitro-2-oxo-1,2-dihydro-1-pyridyl)-1,2-benzisothiazole 1,1-dioxide (BID-NPy), readily prepared from 3-chloro-1,2-benzisothiazole 1,1-dioxide and 5-nitro-2-pyridone, proved to be a very useful condensing reagent.A variety of esters, dipeptides, and lactones were obtained in excellent yields.Furthemore, BID-NPy was successfully employed for the lactonization step in a new synthesis of a naturally occuring (+/-)-(E)-8-dodecen-11-olide, recifeiolide.
- Ahmed, Alauddin,Taniguchi, Nagahiro,Fukuda, Hirohiko,Kinoshita, Hideki,Inomata, Katsuhiko,Kotake, Hiroshi
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p. 781 - 786
(2007/10/02)
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- Tin-mediated esterification in macrolide synthesis
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A neutral and relatively simple new method for effecting internal macrocyclic esterification of omega -hydroxycarboxylic acids, based on a tin 'template-driven' extrusion process, is discussed and its application to the synthesis (macrocyclization step) of the macrolide antibiotics zearalenone, ingramycin, and nodusmicin detailed. An efficient, formal total synthesis of pyrenophorin using this technique is also presented. Attempts to extend the methodology to include the macrocyclization of omega -bromo carboxylic acids or omega -mercapto carboxylic acids were unsuccessful. However, although beta - and omega -amino carboxylic acids preferentially gave way to polymer formation, 4-,5, and 6-amino carboxylic acids readily condensed to give the corresponding five-, six-, and seven-membered lactams in excellent yields. For example, in this way, the bridged lactam 1-azabicyclo- left bracket 3. 3. 1 right bracket nonan-2-one was prepared in 77% yield as compared to the previously reported yield of less than 2%.
- Steliou,Poupart
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p. 7130 - 7138
(2007/10/02)
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- Preparation of Macrocyclic Lactones by Ring Closure of Cesium Carboxylates
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A series of ω-halo fatty acids, the longest being 16-iodohexadecanoic acid, was prepared by oxidation of the corresponding ketones with m-chloroperbenzoic acid in boiling chloroform, followed by ring opening usually with hydrogen iodide in acetic acid at 100 deg C.Solutions of these acids in dimethylformamide (DMF) at concentrations of 5E-3 - 5E-2 M were treated with an equivalent amount of dry Cs2CO3.The solutions were stirred at 40 deg C overnight.Workup of the reaction mixture produced a mixture of (macro)cyclic lactone (macrolide) and its dimer (dilide).For the case of 16-iodohexanoic acid the lactone was isolated in 85percent yield.Yields for other large ring macrolides were also excellent.It was demonstrated that substitution by carboxylate on a secondary halide also goes well to afford the corresponding macrolide with no detectable amount of elimination.The effects of ring size, concentration, and solvent on the ring closure of the cesium carboxylates formed in situ were investigated.DMF is the best solvent of those investigated for the ring closure.Cesium carboxylates also undergo more readily ring closure and in far better yield than the carboxylates of lithium, sodium, potassium, rubidium, silver, thallium, magnesium, strontium, or barium.The S-lactone of ricinelaidic acid was prepared optically pure in 80percent yield from optically pure mesylate of R-ricinelaidic acid, which was treated with cesium carbonate in dry DMF.This demonstrates that the ring closure proceeds with the anticipated SN2 inversion at the hydroxyl-bearing carbon atom.With the same approach optically pure S-zearalenone was protected and subjected to ring opening, and the hydroxyl group was activated as mesylate.Some racemization was found to occur in the ring-opening step.On treatment of this material with dry cesium carbonate in DMF, the desired ring closure took place in 80percent yield to provide an excess of the protected R enantiomer of zearalenone.On the basis of these results, some speculations are made concerning the action of cesium in promoting ring closure to macrocyclic lactones.
- Kruizinga, Wim H.,Kellogg, Richard M.
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p. 5183 - 5189
(2007/10/02)
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- A New Synthesis of Macrocyclic Lactones by Rearrangement of 2-Hydroxyalkyl-2-phenylsulphonylcycloalkanones
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2-Hydroxyalkyl-2-phenylsulphonylcycloalkanones undergo base-catalysed isomerisation into phenylsulphonyl-lactones with incorporation of the side-chain into the ring.
- Bhat, Venkatramana,Cookson, Richard C.
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p. 1123 - 1124
(2007/10/02)
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- Cyanuric chloride, a useful reagent for macrocyclic lactonization
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Six ω-hydroxy acids have been converted to macrocyclic lactones by treatment with cyanuric chloride and triethylamine in acetone at room temperature. The mechanism apparently involves activation of both the carboxyl and hydroxyl groups.
- Venkataraman,Wagle
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p. 1893 - 1896
(2007/10/02)
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