cas 32233-44-6, (4S)-2,2-Dimethyl-1,3-Dioxolane-4-Acetaldehyde

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Modular strategies for structure and function employed by marine cyanobacteria: Characterization and synthesis of pitinoic acids
Novel bioactive lipids were identified from a Guamanian cyanobacterium, the Pseudomonas aeruginosa quorum sensing inhibitor pitinoic acid A (1) and the anti-inflammatory pitinoic acids B (2) and C. The structure of 2 was confirmed by synthesis, which also allowed for biological evaluation. Since 2 is an ester of pitinoic acids A and C, it represents a prodrug strategy to liberate dual biological activity for the management of P. aeruginosa infections and their associated inflammation.
Montaser, Rana,Paul, Valerie J.,Luesch, Hendrik
p. 4050 - 4053
(2013)
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Approaches to the C-24 to C-37 perimeter of Altohyrtin A
Versatile synthetic sequences are described for the C-24 to C-37 perimeter of Altohyrtin A 1. In addition the diastereoselectivity for the reduction of the β-alkoxy ynone system 15 using various hydride reagents is described.
Hermitage, Stephen A.,Roberts, Stanley M.,Watson, Daniel J.
p. 3567 - 3570
(1998)
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Nickel-Catalyzed Cross-Electrophile Coupling of Alkyl Fluorides: Stereospecific Synthesis of Vinylcyclopropanes
The stereospecific reductive cross-electrophile coupling reaction of 2-vinyl-4-halotetrahydropyrans for vinylcyclopropane synthesis is reported. The nickel-catalyzed reaction occurs with both alkyl fluorides and alkyl chlorides. To the best of our knowledge, this is the first reported cross-electrophile coupling reaction of an alkyl fluoride. Ring contraction proceeds with high stereospecificity, providing selective synthesis of either diastereomer of di- and trisubstituted cyclopropanes. The utility of this methodology is demonstrated by several synthetic applications including the synthesis of the natural product dictyopterene A. 2-Vinyl-4-fluorotetrahydrofurans also undergo stereospecific ring contractions, providing access to synthetically useful hydroxymethyl cyclopropanes.
Erickson, Lucas W.,Lucas, Erika L.,Tollefson, Emily J.,Jarvo, Elizabeth R.
supporting information
p. 14006 - 14011
(2016/11/06)

Enantioselective Total Synthesis of Mandelalide A and Isomandelalide A: Discovery of a Cytotoxic Ring-Expanded Isomer
The total synthesis of mandelalide A and its ring-expanded macrolide isomer isomandelalide A has been achieved. Unexpected high levels of cytotoxicity were observed with the ring-expanded isomandelalide A with a rank order of potency: mandelalide A > isomandelalide A > mandelalide B. Key aspects of the synthesis include Ag-catalyzed cyclizations (AgCC's) to construct both the THF and THP rings present in the macrocycle, diastereoselective Sharpless dihydroylation of a cis-enyne, and lithium acetylide coupling with a chiral epoxide.
Veerasamy, Nagarathanam,Ghosh, Ankan,Li, Jinming,Watanabe, Kazuhiro,Serrill, Jeffrey D.,Ishmael, Jane E.,McPhail, Kerry L.,Carter, Rich G.
supporting information
p. 770 - 773
(2016/02/05)

E-Selectin Antagonists Modified By Macrocycle Formation to the Galactose
Provided herein are glycomimetic E-selectin antagonist compounds of formula (I)) and pharmaceutical compositions comprising at least one of the same. The compounds of the present disclosure include trisaccharide domain mimics comprising at least one macro
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Paragraph 0242; 0243

(2016/12/07)

Dibutyltin oxide mediated diastereoselective cyclodehydration/sulfonylation of 1,2,4-triols
Dibutyltin oxide (Bu2SnO) mediated cyclodehydration or sulfonylation of 1,2,4-triols is predictably diastereoselective depending on the steric bulk of the substituents at C4. A larger difference (ΔA-value >1 kcal/mol) leads to the syn-1,2,4-triols favouring cyclodehydration (78-85%) to form 3-hydroxytetrahydrofurans, with the anti-1,2,4-triols favouring monosulfonylation (66-87%). Triols from symmetrical ketones preferentially undergo cyclodehydration in high yield (>75%) due to a gem-disubstituent effect. Thus, the 1,2,4-triols derived from simple cyclic ketones also favour cyclodehydration to form spirocyclic 3-hydroxytetrahydrofurans in 72-79% yields.
Gamedze, Makhosazana P.,Nkambule, Comfort M.
supporting information
p. 1825 - 1829
(2015/03/30)

E-SELECTIN ANTAGONISTS MODIFIED BY MACROCYCLE FORMATION TO THE GALACTOSE
Provided herein are glycomimetic E-selectin antagonist compounds of formula (I)) and pharmaceutical compositions comprising at least one of the same. The compounds of the present disclosure include trisaccharide domain mimics comprising at least one macro
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Paragraph 00162

(2015/08/03)

A new strategy for the synthesis of crucigasterin A, and cytotoxic activity of this compound and its related analogues
Stereoselective total synthesis of bioactive marine natural product crucigasterin A has been accomplished from commercially available and inexpensive l-(-)-malic acid as a starting material. Julia olefination and chelation controlled Grignard additions are the key steps involved in the present synthesis. Cytotoxic properties of crucigasterin A and its related analogues crucigasterins B and D have been evaluated. Crucigasterin A showed promising activities against both the human cervical cancer cell line and human breast adenocarcinoma cell line.
Kumar, Jayprakash Narayan,Reddy, Parigi Raghavendar,Das, Biswanath,Kumar, C. Ganesh,Sujitha, Pombala
p. 5192 - 5194
(2013/09/12)

Transition-metal-free reactions of boronic acids: 1,3-stereochemical induction in the substrate-controlled conjugate addition
The substrate-controlled 1,3-stereoselective conjugate addition of boronic acids and potassium trifluoroborates under metal-free conditions has been developed. This reaction affords bicyclic acetals, which have been used as key intermediates in the stereodivergent synthesis of polysubstituted tetrahydropyrans.
Roscales, Silvia,Ortega, Victor,Csaky, Aurelio G.
p. 12825 - 12830
(2014/01/17)

A macrolactonisation approach to the cembrane carbocycle of bielschowskysin
By judicious choice of a conformationally constraining unit to predispose cyclisation to a 15-membered ring, we present a straightforward strategy to a cembranolide precursor of bielschowskysin by the Sonogashira coupling of two readily prepared fragments (from d-glucose and l-malic acid) followed by a facile β-acylketene macrolactonisation reaction.
Yang, Eugene G.,Sekar, Karthik,Lear, Martin J.
supporting information
p. 4406 - 4408
(2013/07/26)

Studies directed towards the total synthesis of koshikalide: Stereoselective synthesis of the macrocyclic core
The stereoselective synthesis of the macrolactone core of the natural product koshikalide is described. Starting with readily available 1,4-butanediol and malic acid as synthons, our synthetic strategy involved the reiterative application of Gilman's reaction, Swern oxidation and Sharpless asymmetric epoxidation to establish the required stereocentres. Other key steps in the synthesis include Negishi cross coupling and Horner-Wadsworth-Emmons (HWE) reactions for construction of the main fragments. The 14-membered lactone ring was prepared by a selective Mitsunobu macrolactonization approach.
Venkanna, Arramshetti,Sreedhar, Eppakayala,Siva, Bandi,Babu, Katragadda Suresh,Prasad, Kothakonda Rajendra,Rao, Janaswamy Madhusudana
p. 1010 - 1022
(2013/09/23)

Total synthesis of (-)-zampanolide and structure-activity relationship studies on (-)-dactylolide derivatives
A new total synthesis of the marine macrolide (-)-zampanolide (1) and the structurally and stereochemically related non-natural levorotatory enantiomer of (+)-dactylolide (2), that is, ent-2, has been developed. The synthesis features a high-yielding, selective intramolecular Horner-Wadsworth-Emmons (HWE) reaction to close the 20-membered macrolactone ring of 1 and ent-2. The β-keto phosphonate/aldehyde precursor for the ring-closure reaction was obtained by esterification of a ω-diethylphosphono carboxylic acid fragment and a secondary alcohol fragment incorporating the THP ring that is embedded in the macrocyclic core structure of 1 and ent-2. THP ring formation was accomplished through a segment coupling Prins-type cyclization. Employing the same overall strategy, 13-desmethylene-ent-2 as well as the monocyclic desTHP derivatives of 1 and ent-2 were prepared. Synthetic 1 inhibited human cancer cell growth in vitro with nM IC50 values, while ent-2, which lacks the diene-containing hemiaminal-linked side chain of 1, is 25- to 260-fold less active. 13-Desmethylene-ent-2 as well as the reduced versions of ent-2 and 13-desmethylene-ent-2 all showed similar cellular activity as ent-2 itself. The same activity level was attained by the monocyclic desTHP derivative of 1. Oxidation of the aldehyde functionality of ent-2 gave a carboxylic acid that was converted into the corresponding N-hexyl amide. The latter showed only μM antiproliferative activity, thus being several hundred-fold less potent than 1. It's the side chain that matters: The marine macrolide (-)-zampanolide (1) has been synthesized via (-)-dactylolide (ent-2), the non-natural enantiomer of the marine natural product (+)-dactylolide (2), employing a high-yielding intramolecular Horner-Wadsworth-Emmons reaction to close the macrolactone ring. While the hemiaminal-linked side chain in 1 is crucial for nanomolar antiproliferative activity, the methylene group and the aldehyde functionality in ent-2 are dispensable. A monocyclic destetrahydropyran derivative of 1 shows equal activity as ent-2. Copyright
Zurwerra, Didier,Glaus, Florian,Betschart, Leo,Schuster, Julia,Gertsch, Jürg,Ganci, Walter,Altmann, Karl-Heinz
supporting information
p. 16868 - 16883
(2013/03/14)

Stereoselective synthesis of tetrahydropyranyl diarylheptanoids (-)-centrolobine and (+)-centrolobine
A versatile chiron approach to the tetrahydropyranyl diarylheptanoid natural products (-)-centrolobine and (+)-centrolobine has been described. The use of an aldol reaction followed by reductive etherification for the formation of tetrahydropyran ring is of importance. Georg Thieme Verlag Stuttgart · New York.
Reddy, Chada Raji,Madhavi, Pasupulety Phani,Chandrasekhar, Srivari
scheme or table
p. 123 - 126
(2011/02/26)

C(21)-C(40) of tetrafibricin via metal catalysis: Beyond stoichiometric chiral reagents, auxiliaries, and premetalated nucleophiles
Chemical equations presented. The C(21)-C(40) fragment of fibrinogen receptor inhibitor tetrafibricin was prepared in 12 steps from propane diol (longest linear sequence). In this approach, 6 C-C bonds are formed via asymmetric iridium catalyzed transfer
Kumpulainen, Esa T. T.,Kang, Byungsoo,Krische, Michael J.
supporting information; scheme or table
p. 2484 - 2487
(2011/07/09)

Application of stereoselective ether transfer to the synthesis of isotactic polyethers
An efficient, convergent synthetic strategy has been developed which enables the synthesis of a series of naturally occurring isotactic polymethoxy compounds. Ether transfer followed by a hydride workup enables simultaneous, diastereoselective production of two methoxy centers in a single step. High yields and diastereoselectivity are observed even in stereochemically rich, polyoxygenated systems. Direct generation of bis-methyl ether moieties from methoxymethyl ethers minimizes the need for typical protective group strategies and the use of expensive methyl transfer reagents. Moreover, the simultaneous generation of a terminal primary iodide serves as a coupling partner for the generation of higher order congeners.
Liu, Kai,Arico, Joseph W.,Taylor, Richard E.
scheme or table
p. 3953 - 3957
(2010/08/07)

Fluorous mixture synthesis of four stereoisomers of the C21-C40 fragment of tetrafibricin
Four stereoisomers of the C21-C40 fragment are synthesized in a single exercise with the aid of fluorous tagging to encode configurations at C37 and C33. After demixing and detagging, the isomers were found to have substantially identical 1H NM
Zhang, Kai,Curran, Dennis P.
supporting information; experimental part
p. 667 - 671
(2010/12/18)

Total synthesis of nonenolide
A novel synthetic route has been reported for the synthesis of nonenolide. The syntheses of fragments were initiated from commercially available and inexpensive starting materials. The synthesis involves key steps like Sharpless epoxidation, Jacobsen's re
Meshram, Harshadas Mitaram,Kumar, Dachepally Aravind,Ramesh, Palakuri
scheme or table
p. 1422 - 1427
(2010/09/12)

Total synthesis of incednam, the aglycon of incednine
The first total synthesis of incednam (1), the aglycon of antibiotic incednine (2), is described. Incednine has been reported to exhibit significant inhibitory activity against the antiapoptotic oncoproteins Bcl-2 and Bcl-xL. The synthesis of 1 commenced
Ohtani, Takashi,Tsukamoto, Shinya,Kanda, Hiroshi,Misawa, Kensuke,Urakawa, Yoshifumi,Fujimaki, Takahiro,Imoto, Masaya,Takahashi, Yoshikazu,Takahashi, Daisuke,Toshima, Kazunobu
supporting information; experimental part
p. 5068 - 5071
(2010/12/25)

Studies on synthesis of the C-1 to C-18 fragment of pamamycins 607 and 621A
Some efforts directed towards synthesis of the C-1 to C-18 fragment of natural antibiotic pamamycins 607 and 621A are disclosed. The nine stereogenic centers in the fragment were installed using a chiral auxiliary-induced asymmetric aldol reaction, a chir
Ren, Guobao,Wu, Yikang
experimental part
p. 1651 - 1659
(2011/08/02)

Sulfanylation of 1,3-dithiane anions by 5-(alkylsulfanyl)-l- phenyltetrazoles
An unusual reaction between 1,3-dithiane anions and by 5-(alkylsulfanyl)-l- phenyltetrazoles has been discovered in which the dithiane anion formally displaces the 1-phenyltetrazole ring from sulfur to provide a sulfanylated dithiane.
Gudipati, Venugopal,Bajpai, Reena,Curran, Dennis P.
experimental part
p. 771 - 783
(2010/02/16)

Stereocontrolled entry to the tricyclo[3.3.0]oxoheptane core of bielschowskysin by a [2+2] cycloaddition of an allene-butenolide
As part of ongoing transannulation studies, the practical synthesis of an allene-linked γ-butenolide from l-malic acid and its substrate-controlled [2+2] photocycloaddition to the tricyclic core of bielschowskysin (1) are described.
Miao, Ru,Gramani, Subramanian G.,Lear, Martin J.
supporting information; experimental part
p. 1731 - 1733
(2009/07/05)

A Pd-mediated intramolecular ketalization of alkynediols: construction of the central [3.2.1]-bicyclic ketal core of cyclodidemniserinol trisulfate
A preliminary study dealing with the Pd-mediated alkynediol cycloisomerization to construct the central bicyclic ketal core of cyclodidemniserinol trisulfate is documented.
Ramana,Mallik, Rosy,Sahoo, Gokarneswar
body text
p. 4844 - 4847
(2009/11/30)

Concise asymmetric synthesis of antimalarial alkaloid (+)-febrifugine
An asymmetric total synthesis of antimalarial alkaloid (+)-febrifugine is accomplished in 23% overall yield over 14 steps from readily available starting materials. The synthesis features a SmI2-mediated reductive cross-coupling of chiral N-ter
Wang, Rui,Fang, Kai,Sun, Bing-Feng,Xu, Ming-Hua,Lin, Guo-Qiang
scheme or table
p. 2301 - 2304
(2009/12/08)

Solid-phase synthesis of [5.5]-spiroketals
An efficient and reliable multi-step synthesis of 251 natural product-like [5.5]-spiroketals on solid supports has been developed. As central key step, a double intramolecular hetero-Michael (DIHMA) reaction to alkynones was applied. The sequence allows for introduction of numerous substituents on the scaffold and for variation of stereochemistry. [5.5]-Spiroketals bearing an additional ketone were obtained in high overall yields. Further diversification was achieved by reduction of the ketone and reductive amination using polymer-supported borohydride, Grignard reaction and conversion to oxime derivatives in the solution phase.
Sommer, Stefan,Kuehn, Marc,Waldmann, Herbert
supporting information; experimental part
p. 1736 - 1750
(2009/08/14)

α-CHLORO AND α-BROMO PHOSPHONATE ANALOGS OF LYSOPHOSPHATIDIC ACID AND METHODS OF MAKING AND USING THEREOF
Described herein is the synthesis and pharmacology of a series of α- substituted methylene phosphonate analogs, in which the α-CH2 moiety is replaced with CHCl or CHBr.
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Page/Page column 19-20

(2009/01/23)

Synthesis and biological evaluation of (-)-dictyostatin and stereoisomers
Total syntheses of (-)-dictyostatin, 6,16-bis-epi-dictyostatin, 6,14,19-tris-epi-dictyostatin, and a number of other isomers and analogs are reported. Three main fragments-top, middle, and bottom-were first assembled and then joined by olefination or anio
Shin, Youseung,Fournier, Jean-Hugues,Brückner, Arndt,Madiraju, Charitha,Balachandran, Raghavan,Raccor, Brianne S.,Edler, Michael C.,Hamel, Ernest,Sikorski, Rachel?P.,Vogt, Andreas,Day, Billy W.,Curran, Dennis P.
p. 8537 - 8562
(2008/02/09)

On the stereochemistry of palmerolide A
Degradative studies of the anticancer macrolide palmerolide A have resulted in re-assignment of the C-7, C-10, and C-11 stereocenters.
Lebar, Matthew D.,Baker, Bill J.
p. 8009 - 8010
(2008/03/18)

Synthesis and highly stereoselective hydrogenation of the statin precursor ethyl (5S)-5,6-isopropylidenedioxy-3-oxohexanoate
A search for the large-scale preparation of (5S)-5,6-(isopropylidenedioxy)- 3-oxohexanoates (2) - a key intermediate in the synthesis of pharmacologially important statins - starting from (S)-malic acid is described. The synthesis of the required initial compound methyl (3S)-3,4-(isopropylidenedioxy)butanoate (1) by Moriwake's reduction of dimethyl (S)-malate (3) has been improved. Direct 2-C chain elongation of ester 1 using the lithium enolate of tert-butyl acetate has been shown to be successful at a 3- to 5-fold excess of the enolate. Unfortunately, the product, tert-butyl (5S)-5,6-(isopropylidenedioxy)-3- oxohexanoate (2a) is unstable during distillation. Ethyl (5S)-5,6- (isopropylidenedioxy)-3-oxohexanoate (2b) was prepared alternatively on a multigram scale from (3S)-3,4-(isopropylidenedioxy)butanoic acid (7) by activation with N,N′-carbonyldiimidazole and subsequent reaction with Mg(OOCCH2COOEt)2. A convenient pathway for the in situ preparation of the latter is also described. Ethyl ester (2b) can be advantageously purified by distillation. The stereochemistry of the catalytic hydrogenation of β-keto ester (2b) to ethyl (55)-5,6-(isopropylidenedioxy)- 3-hydrohyhexanoate (syn-6 and anti-6) has been studied using a number of homogeneous achiral and chiral Rh(I) and Ru(II) complexes with phosphine ligands. A comparison of Rh(I) and Ru(II) catalysts with (S)- and (R)-BINAP as chiral ligands revealed opposite activity in dependence on the polarity of the solvent. No influence of the chiral backbone of substrate 2b on the enantioselectivity was noted. A ratio of syn-6/anti-6 = 2.3 was observed with an achiral (Ph3P)3RuCl2 catalyst. Ru[(R)-Tol-BINAP]Cl2 neutralized with one equivalent of AcONa afforded the most efficient catalytic system for the production of optically pure syn-(5S)-5,6-isopropylidenedioxy-3-hydroxyhexanoate (syn-6) at a preparative substrate/catalyst ratio of 1000:1.
Tararov, Vitali I.,Koenig, Gerd,Boerner, Armin
p. 2633 - 2644
(2007/10/03)

Mild organocatalytic α-methylenation of aldehydes
A rapid and extremely convenient method for α-methylenation of aldehydes with aqueous formaldehyde is described. Two optimal catalytic systems are presented that allow short reaction times and afford the functionalized products in good to excellent yields (up to 99%) and chemoselectivity.
Erkkil?, Anniina,Pihko, Petri M.
p. 2538 - 2541
(2007/10/03)

Allylic stereocontrol of the intramolecular diels-alder reaction
The stereochemical outcome of the intramolecular Diels-Alder reaction of ester-linked 1,3,8-nonatrienes can be controlled by substituants about a stereogenic center attached to Cl. The scope and limitations of this approach have been investigated, with variation in substrate structure about the allylic stereocenter and the dieno phile. The stereochemical outcomes of these reactions are explained by reference to B3LYP/6-31G(d) transition structures. New insights into the conformational preferences of allylic alcohol derivatives are reported, results which allow an explanation of the differing levels of π-diastereofacial selectivity and cis/trans (i.e. endo/exo) selectivity from the reaction.
Lilly, Michael J.,Miller, Natalie A.,Edwards, Alison J.,Willis, Anthony C.,Turner, Peter,Paddon-Row, Michael N.,Sherburn, Michael S.
p. 2525 - 2536
(2007/10/03)

ANALOGS OF DISCODERMOLIDE AND DICTYOSTATIN-1, INTERMEDIATES THEREFOR AND METHODS OF SYNTHESIS THEREOF
A compound of the following structure: wherein R1 is H, an alkyl group, an aryl group, an alkenyl group, an alkynyl group, or a halogen atom; R2 is H, an alkyl group, an aryl group, a benzyl group, a trityl group, -SiRaRbRc, CH2ORd, or CORe; Ra, Rb and Rc are independently an alkyl group or an aryl group; Rd is an alkyl group, an aryl group, an alkoxylalkyl group, -RiSiRaRbRc or a benzyl group, wherein Ri is an alkylene group; Re is an alkyl group, an allyl group, a benzyl group, an aryl group, an alkoxy group, or -NRgRh, wherein Rg and Rh are independently H, an alkyl group or an aryl group; R3 is (CH2)n where n is and integer in the range of 0 to 5, -CH2CH(CH3)-, -CH=CH-, -CH=C(CH3)-, or -C=-C-; R4 is (CH2)p where p is an integer in the range of 4 to 12, -(CHRkl)yl (CHRk2)y2(CHRk3)y3(CHRk4)y4(CHRk5)y5C(Rsl )=C(Rs2)C(Rs3)=C(Rs4)-, -(CHRk1 )yl (CHRk2)y2(CHRk3)y3(CHRk4)y4(CHRk5)y5CH(RsI)CH(Rs2)C(Rs3)=C(Rs4)-, -(CHRk1)yl (CHRk2)y2(CHRk3)y3(CHRk4)y4(CHRks)y5C(Rsl)=C(Rs2)CH(Rs3)CH(Rs4)-, -(CHRkI )yl (CHRk2)y2(CHRk3)y3(CHRk4)y4(CHRk5)y5CH(Rsl)CH(Rs2)CH(Rs3)CH(R s4)-,wherein y1 and y2 are 1 and y3, y4 and y5 are independently 0 or 1, Rk1, Rk2, Rk3, Rk4 and Rk5 are independently H, CH3, or OR2a, and Rs1,Rs2, Rs3, and Rs4 are independently H or CH3, wherein R2a is H, an alkyl group, an aryl group, a benzyl group, a trityl group, -SiRaRbRc, CH2ORd, or CORe; and R5 is H or OR2b, wherein R2b is H, an alkyl group, an aryl group, an aryl group, a benzyl group, a trityl group, -SiRaRbRc, CH2ORd, or CORe; provided that the compound is not dictyostatin 1.
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Figure 13

(2008/06/13)

Synthesis of difluoromethyl substituted lysophosphatidic acid analogues
Lysophosphatidic acid (LPA, 1- or 2-acyl-sn-glycerol 3-phosphate) displays an intriguing cell biology that is mediated via interactions both with G-protein coupled seven transmembrane receptors and with nuclear hormone receptor PPARγ. We describe a new and efficient route to enantiomerically homogeneous lysophospholipid analogues from (S)-1,2,4-butanetriol to give two 3-difluoromethyl substituted analogues of 2-acyl-sn-glycerol 3-phosphate. These compounds are migration-blocked analogues of the liable sn-2 LPA species. Preliminary studies were conducted on a nuclear reporter assay in which monocytic cells were transfected with a luciferase construct activated by a PPARγ nuclear receptor response element and have shown that the 3-difluoromethyl substituted analogues are fully active as natural LPA.
Xu, Yong,Qian, Lian,Pontsler, Aaron V.,McIntyre, Thomas M.,Prestwich, Glenn D.
p. 43 - 49
(2007/10/03)

Synthesis of (R)-2-methyl-4-deoxy and (R)-2-methyl-4,5-dideoxy analogues of 6-phosphogluconate as potential inhibitors of 6-phosphogluconate dehydrogenase.
The synthesis of (2R)-2-methyl-4,5-dideoxy and (2R)-2-methyl-4-deoxy analogues of 6-phosphogluconate is described. The synthetic strategy relies on the Evans aldol reaction for the installation of the chiral centres in the 2- and 3-positions. The selective phosphorylation at the primary alcohol function of (2R,3S)-3,6-dihydroxy-2-methylhexanoic acid benzyl ester (5) and (2R,3S,5S)-3,5,6-trihydroxy-2-methylhexanoic acid benzyl ester (20) was achieved with dibenzyl phosphochloridate and dibenzyl phosphoiodinate respectively, working at low temperature. (2R,3S)-3-Hydroxy-2-methyl-6-phosphonoxyhexanoic acid (9) was obtained in 25% overall yield from 4-benzyloxybutanol and (2R,3S,5S)-3,5-dihydroxy-2-methyl-6-phosphonoxyhexanoic acid (28) in 10% overall yield from L-malic acid.
Dardonville, Christophe,Gilbert, Ian H
p. 552 - 559
(2007/10/03)

Synthesis of monofluorinated analogues of lysophosphatidic acid
Lysophosphatidic acid (LPA, 1- or 2-acyl-sn-glycerol 3-phosphate) displays an intriguing cell biology that is mediated via interactions both with G-protein coupled seven transmembrane receptors and with the nuclear hormone receptor PPARγ. Synthesis and bi
Xu, Yong,Qian, Lian,Prestwich, Glenn D.
p. 5320 - 5330
(2007/10/03)

Total synthesis of pederin, a potent insect toxin: The efficient synthesis of the right half, (+)-benzoylpedamide
A simple and efficient synthesis of (+)-benzoylpedamide, the right half of pederin, was achieved in 16 steps with a 35% overall yield from (S)-malic acid. The key steps include the SmI2-mediated intramolecular Reformatsky reaction, stereoselective allylation, the Sharpless asymmetric dihydroxylation, and amidation. The total synthesis of pederin was accomplished via coupling of the left and right halves.
Takemura, Takahiro,Nishii, Yoshinori,Takahashi, Shunya,Kobayashi, Jun'ichi,Nakata, Tadashi
p. 6359 - 6365
(2007/10/03)

A concise synthesis of (+)-compactin lactone by asymmetric dihydroxylation and regioselective cyclic sulfite opening reactions
A concise, enantioselective synthesis of compactin lactone 2 is described using the Sharpless asymmetric dihydroxylation and regioselective nucleophilic opening of cyclic sulfite as the key steps. Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002.
Fernandes, Rodney A.,Kumar, Pradeep
p. 2921 - 2923
(2007/10/03)

Diastereoselective synthesis of 2,3,5-trisubstituted tetrahydrofurans via cyclofunctionalization reactions. Evidence of stereoelectronic effects
The work described herein considers the impact of stereoelectronic effects and allylic 1,3-strain in controlling the cyclofunctionalization reaction when a hydroxyl group is at the allylic position. The stereoelectronic arguments are supported by independent iodocyclization reactions performed using two secondary alcohols. The transition-state pathways involved in these reactions are established through a comparison of relative reaction rates. A bi-directional approach is used to demonstrate the potential of the iodocyclization reaction to differentiate a terminus in molecules with a pseudo C2 axis of symmetry, showing that two-directional synthesis can be used to differentiate between alternative transition-state pathways.
Guindon,Soucy,Yoakim,Ogilvie,Plamondon
p. 8992 - 8996
(2007/10/03)

Enantiospecific synthesis of the (9S,18R)-diastereomer of the leukocyte adhesion inhibitor cyclamenol A
Cyclamenol A is one of the very few non-carbohydrate and non-peptide natural products that inhibit leukocyte adhesion to endothelial cells. We report on the first enantioselective total synthesis of the (9S, 18R)-diastereomer of this macrocyclic polyene lactam. Key elements of the synthesis are i) the synthesis of the required chiral building blocks by employing readily accessible building blocks from the chiral pool, that is, (S)-malic acid and (R)-hydroxyisobutyric acid, ii) assembly of a linear polyene precursor by means of Wittig and Horner olefination reactions as key C-C bond-forming transformations, iii) ring closure by means of a vanadium-mediated pinacolisation reaction and iv) conversion of the generated cis-diol into a (Z)-olefin to complete the entire polyene system of the natural product. Attempts to close the macrocyclic ring by a macrolactamisation, a double Stille coupling or direct olefination in a McMurry reaction failed. Crucial to the successful completion of the synthesis was the correct orchestration of the final steps. It was necessary to first deprotect the intermediate formed after macrocycle formation and to generate the sensitive heptaene system in the last step by means of a Corey-Hopkins sequence.
Nazare, Marc,Waldmann, Herbert
p. 3363 - 3376
(2007/10/03)

Studies on the total synthesis of macrolactin A. A stereoselective synthesis of the C3-C13 and C14-C24 fragments
Synthetic studies towards the C3-C13 (2) and C14-C24 (3) segments of the potent antiviral and antitumor compound macrolactin A (1) are presented. Segment 2 was constructed via a convergent and facile approach, exploiting Wittig olefination to generate the sensitive E,Z-diene-moiety. Segment 3 was obtained from the chiral pool derived sulfone 4 via an α- alkylation-desulfonation reaction sequence. (C) 2000 Elsevier Science Ltd.
Li, Shukun,Xu, Rui,Bai, Donglu
p. 3463 - 3466
(2007/10/03)

Synthesis of the H-I-J tricyclic fragment of ciguatoxin, a marine polyether toxin
During the course of our synthetic studies on ciguatoxin, synthesis of H-I-J tricyclic fragment has been stereoselectively achieved starting from a D-glucal derivative. The key steps are Sonogashira coupling reaction and cobalt complex-mediated oxocane cyclization.
Liu, Tong-Zhu,Isobe, Minoru
p. 266 - 268
(2007/10/03)

Synthetic studies on the HIJK-ring fragment of ciguatoxin
Synthesis of the tetracyclic HIJK-ring fragment of ciguatoxin with high stereoselectivity has been achieved starting from a sugar derivative directed toward the synthesis of the right part of ciguatoxin. Sonogashira coupling of a vinyl iodide with an acetylene derivative, cobalt complex-mediated (seven- and eight-membered ring) cyclizations and a heteroconjugate addition reaction play important roles in the current research work. (C) 2000 Elsevier Science Ltd.
Liu, Tong-Zhu,Isobe, Minoru
p. 5391 - 5404
(2007/10/03)

Synthesis of the (9S,18R) diastereomer of cyclamenol A
A vanadium-mediated pinacol coupling reaction was the key step in the synthesis of the polyene macrolactam (9S,18R)-cyclamenol A (1). The natural diastereomer (configuration not known) inhibits the adhesion of leukocytes to endothelial cells, a key event in the response to inflammation, tissue injury, and infection.
Nazare, Marc,Waldmann, Herbert
p. 1125 - 1128
(2007/10/03)

Stereoselective preparation of O-alkoxy D-tetrose, D-pentose, 2-deoxy- D-glycero tetrose and 2,3-dideoxy-D-erythro pentose derivatives by an iterative elongation of 2,3-O-isopropylidene-D-glyceraldehyde
All D-pentoses are synthesized by one-carbon chain elongation commencing with the addition of the lithium salt of ethyl ethylthiomethyl sulfoxide to 2-O-(t-butyldimethylsilyl)-3,4-O-isopropylidene-D-erythrose and D-threose, 16 and 17. The addition of the
Arroyo-Gomez,Lopez-Sastre,Rodriguez-Amo,Santos-Garcia,Sanz-Tejedor
p. 973 - 990
(2007/10/03)

Synthesis of isomeric nucleoside phosphonates: Cyclic analogs of the anti-HIV active compound, PMEA
Synthesis of cyclic analogs of the anti-HIV active acyclic nucleoside phosphonate, PMEA is described. A key reaction in the synthesis was the stereoselective cyclization of an acyclic phosphonyl intermediate to a phosphonyltetrahydrofuran. Complete stereo
Zheng, Xiaoping,Nair, Vasu
p. 11803 - 11818
(2007/10/03)

Studies of acyl nitrene insertions. A stereocontrolled route toward lankacidin antibiotics
Photochemically generated acyl nitrenes undergo facile addition to 4,5- dihydrofurans 20 and 24b to yield the novel 2-ethoxyoxazolines 21 and 25. The regiocontrolled C=C insertion has provided for introduction of the sterically hindered C-3 amido appendage of the lankacidins 1-4 with high stereoselectivity. High chemoselectivity for the C=C insertion pathway was demonstrated upon production of the acyl nitrene intermediate from azide 33b. Intramolecular competition for allylic C3-H insertion versus C=C addition yielded exclusive formation of seven-membered N-acyl aziridines 34a,b. The latent aldehydic functionality of oxazolines such as 21 and 25 is exposed upon a brief hydrolysis, permitting further chemical elaboration. Wittig condensation of the lactol from 25 has led to the synthesis of the lactone fragment 5, containing all of the necessary stereochemistry and functionality for incorporation into the lankacidin antibiotics. The acyl nitrene insertion into 4,5-dihydrofurans affords a route toward unusual β-amido acids and amino sugar derivatives as shown via stereocontrolled formation of the amidofuranose derivatives 31 and 32. The three-step process of acyl nitrene addition, hydrolysis of the resulting 2,5-dialkoxy oxazoline intermediates, and Wittig carbon chain elongation provides the stereocontrolled formation of novel β-amido esters.
Williams, David R.,Rojas, Christian M.,Bogen, Stephane L.
p. 736 - 746
(2007/10/03)

Syntheses of L-threose and D-erythrose analogues modified at position 2
2-O-Methyl-D-erythrose, 2-O-methyl-L-threose, 2-deoxy-D- and L- erythrose, and the corresponding acetonides have been prepared from the commercially available D-isoascorbic and L-ascorbic acids. The proportion of cyclic (α and β furanoses) and acyclic (aldehyde and hydrate) forms was determined in aqueous (D2O) solution by 1H and 13C NMR spectroscopy.
Andre, Corinne,Bolte, Jean,Demuynck, Colette
p. 1359 - 1367
(2007/10/03)

Stereocontrolled synthesis of the CD subunit of the marine macrolide altohyrtin A
A synthesis of the C17-C28 segment of altohyrtin A is reported. The synthesis uses a coupling step between two chiral subunits, both of which were synthesized from L-malic acid. The remaining stereocenters were obtained through a combination of stereoselective reactions and thermodynamic equilibration.
Zemribo, Ronald,Mead, Keith T.
p. 3895 - 3898
(2007/10/03)

A chiron approach to the cyclopropyl lactone oxylipins
Enantiomerically pure key intermediates for the synthesis of constanolactones A and B and solandelactones A, B, E and F, the hydroxy- protected (3S,5Z)-undec-1-yn-5-en-3-ol and (3S,1E,5Z)-1-iodoundec-1,5-dien- 3-ol, have been obtained in nine steps starting from (S)-malic acid.
Barloy-Da Silva,Pale
p. 3951 - 3954
(2007/10/03)

Total synthesis of milbemycin E: Synthesis of the C(11)-C(25) fragment
Treatment of 2-methylpropanal with the (E)-but-2-enyl(diisopinocampheyl)borane 9 prepared from (+)-α-pinene gives the anti- and syn-products 10 and 11, ratio 88:12, from which the major anti-isomer 10 is separated by preparative GLC. Hydroboration-oxidation of its tert-butyldimethylsilyl ether 14 gives the primary alcohol 15 which has been converted into the bromide 16 and iodide 17. The propenyl(diisopinocampheyl)borane 23 prepared from (-)-α-pinene reacts with the aldehyde 22 prepared from (S)-malic acid to give the anti- and syn-1,3-diol derivatives 24 and 25, ratio 86:14, and the anti-product 24 has been taken through to the epoxide 31. Sequential alkylation of 1,3-dithiane with the iodide 17 and the epoxide 31 gives the 2,2-dialkyl-1,3-dithiane 33 which is converted into the spiroacetal 4 by treatment with dilute aqueous hydrogen fluoride. After protection, ozonolysis gives the aldehyde 43 which has been condensed with the ylide 34 to give the α,β-unsaturated ester 44. This has been reduced and converted into the iodide 46 which has been used to alkylate the chiral oxazolidinone 39 to give the required C(11)-C(25) fragment 48 of milbemycin E 1 after reductive removal of the chiral auxiliary. This has been converted into the phosphonium salt 2 ready for Wittig coupling with the hydroxybutenolide 3 for the assembly of the milbemycin nucleus.
Steel, Patrick G.,Thomas, Eric J.
p. 371 - 380
(2007/10/03)

Bakers' yeast oxidation of methyl para-tolylsulfide: Synthesis of a chiral intermediate in the preparation of the mevinic acid-type hypocholestemic agents
The use of (R)-methyl-para-tolylsulfoxide as a chiral auxiliary in a novel synthesis of a key intermediate en route to mevinic acid-type hypocholestemic agents is described. The synthesis is short and simple consisting of eight steps to yield enantiomeric
Tang, Jenny,Brackenridge, Ian,Roberts, Stanley M.,Beecher, Jean,Willetts, Andrew J.
p. 13217 - 13238
(2007/10/02)