- A synthesis of petrofuran based on the enantioselective reduction of 1- trimethylsilyl-4-alken-1-yn-3-ones
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Highly enantioenriched 4-alken-1-yn-3-ol moiety (1), present in many bioactive acetylenic metabolites from sponges, has been efficiently obtained by reduction of the parent 1-trimethylsilyl-4-alken-1-yn-3-one (2) with Alpine-Borane or with BH3 · SMe2 in the presence of chiral oxazaborolidines, followed by desilylation of the resulting alcohol. This strategy has been applied to the first stereoselective synthesis of petrofuran 3.
- Garcia,López,Romeu
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Read Online
- (ω-2,ω-2,ω-3,ω-3)-Tetradeuterio-fatty acids for mechanistic studies of enzyme-catalyzed hydroxylation reactions
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Among the thousands of cytochrome P450 enzymes known, many selectively hydroxylate the hydrocarbon tail of fatty acids at the terminal (ω) position and the ω-1, ω-2, and ω-3 positions. A general method for synthesis of (ω-2,ω-2,ω-3,ω-3)-tetradeuterio-fatty acids that can be used in mechanistic studies of cytochromes P450 is illustrated by the synthesis of 9,9,10,10-tetradueteriododecanoic (lauric) acid and 13,13,14,14-tetradeuteriohexadecanoic (palmitic) acid. Deuterium is introduced early in the synthesis by reduction of the THP ether of 4-heptyn-1-ol with deuterium gas to give a common labeled intermediate, 4,4,5,5- tetradeuterioheptan-1-ol. This alcohol is converted to the corresponding tosylate that is used to alkylate O-protected (ω-1)-alkyn-1-ols to give, eventually, long-chain alcohols that are oxidized to the corresponding fatty acids. An important experimental detail is that relatively large amounts of Wilkinson's catalyst were used to limit isotopic scrambling. Copyright
- Horner, John H.,Newcomb, Martin
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- Catalytic Access to Functionalized Allylic gem-Difluorides via Fluorinative Meyer–Schuster-Like Rearrangement
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An unprecedented approach for efficient synthesis of functionalized allylic gem-difluorides via catalytic fluorinative Meyer–Schuster-like rearrangement is disclosed. This transformation proceeded with readily accessible propargylic fluorides, and low-cost B–F reagents and electrophilic reagents by sulfide catalysis. A series of iodinated, brominated, and trifluoromethylthiolated allylic gem-difluorides that were difficult to access by other methods were facilely produced with a wide range of functional groups. Importantly, the obtained iodinated products could be incorporated into different drugs and natural products, and could be expediently converted into many other valuable gem-difluoroalkyl molecules as well. Mechanistic studies revealed that this reaction went through a regioselective fluorination of alkynes followed by a formal 1,3-fluorine migration under the assistance of the B–F reagents to give the desired products.
- An, Rui,Li, Huimin,Liao, Lihao,Wu, Jin-Ji,Xu, Yang,Zhao, Xiaodan
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supporting information
p. 11010 - 11019
(2020/05/18)
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- An unprecedented medium-chain diunsaturated n-acylhomoserine lactone from marine roseobacter group bacteria
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N-acylhomoserine lactones (AHLs), bacterial signaling compounds involved in quorum-sensing, are a structurally diverse group of compounds. We describe here the identification, synthesis, occurrence and biological activity of a new AHL, N-((2E,5Z)-2,5-dodecadienoyl)homoserine lactone (11) and its isomer N-((3E,5Z)-3,5-dodecadienoyl)homoserine lactone (13), occurring in several Roseobacter group bacteria (Rhodobacteraceae). The analysis of 26 strains revealed the presence of 11 and 13 in six of them originating from the surface of the macroalgae Fucus spiralis or sediments from the North Sea. In addition, 18 other AHLs were detected in 12 strains. Compound identification was performed by GC/MS. Mass spectral analysis revealed a diunsaturated C12 homoserine lactone as structural element of the new AHL. Synthesis of three likely candidate compounds, 11, 13 and N-((2E,4E)-2,4-dodecadienoyl)homoserine lactone (5), revealed the former to be the natural AHLs. Bioactivity test with quorum-sensing reporter strains showed high activity of all three compounds. Therefore, the configuration and stereochemistry of the double bonds in the acyl chain seemed to be unimportant for the activity, although the chains have largely different shapes, solely the chain length determining activity. In combination with previous results with other Roseobacter group bacteria, we could show that there is wide variance between AHL composition within the strains. Furthermore, no association of certain AHLs with different habitats like macroalgal surfaces or sediment could be detected.
- Ziesche, Lisa,Wolter, Laura,Wang, Hui,Brinkhoff, Thorsten,Pohlner, Marion,Engelen, Bert,Wagner-D?bler, Irene,Schulz, Stefan
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- Direct Access to Allenylphosphine Oxides via a Metal Free Coupling of Propargylic Substrates with P(O)H Compounds
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A direct and convenient approach for the coupling of propargylic substrates with diphenylphosphine oxide in the presence of Tf2O and 2,6-lutidine has been developed. The method provides a general approach for the construction of attractive allenylphosphoryl skeletons with high atom and step economy under metal free conditions.
- Yang, Chun-Hua,Fan, Huihui,Li, Huimin,Hou, Shenyin,Sun, Xiangkun,Luo, Donghao,Zhang, Yinchao,Yang, Zhantao,Chang, Junbiao
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supporting information
p. 9438 - 9441
(2019/11/20)
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- Divergent gold-catalysed reactions of cyclopropenylmethyl sulfonamides with tethered heteroaromatics
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Cyclopropenylmethyl sulfonamides with tethered heteroaromatics have been demonstrated to undergo divergent gold-catalysed cyclisation reactions. A formal dearomative (4+3) cycloaddition takes place with furan-tethered substrates, yielding densely functionalised 5,7-fused heterocycles related to the bioactive curcusone natural products. Indole-tethered substrates display divergent reactivity giving biologically important tetrahydro-β-carbolines via a Friedel-Crafts mechanism.
- Drew, Melanie A.,Arndt, Sebastian,Richardson, Christopher,Rudolph, Matthias,Hashmi, A. Stephen K.,Hyland, Christopher J. T.
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supporting information
p. 13971 - 13974
(2019/11/25)
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- Enantioselective Rhodium-Catalyzed Dimerization of ω-Allenyl Carboxylic Acids: Straightforward Synthesis of C2-Symmetric Macrodiolides
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Herein, we report on the first enantioselective and atom-efficient catalytic one-step dimerization method to selectively transform ω-allenyl carboxylic acids into C2-symmetric 14- to 28-membered bismacrolactones (macrodiolides). This convenient asymmetric access serves as an attractive route towards multiple naturally occuring homodimeric macrocyclic scaffolds and demonstrates excellent efficiency to construct the complex, symmetric core structures. By utilizing a rhodium catalyst with a modified chiral cyclopentylidene-diop ligand, the desired diolides were obtained in good to high yields, high diastereoselectivity, and excellent enantioselectivity.
- Steib, Philip,Breit, Bernhard
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supporting information
p. 6572 - 6576
(2018/05/08)
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- Rhodium-catalyzed hydroformylation of 1,1-disubstituted allenes employing the self-assembling 6-DPPon system
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Abstract A rhodium-catalyzed hydroformylation of 1,1-disubstituted allenes is reported. Using a RhI/6-DPPon catalyst system, one can obtain β,γ-unsaturated aldehydes in high regio- and chemoselectivity. The Z-configured product is formed with up to >95% selectivity when unsymmetrically 1,1-disubstituted allenes are submitted to the reaction conditions. This is the first time that these interesting building blocks are accessible by hydroformylation of allenes. The utility of this methodology is demonstrated by further transformations of one of the obtained products. β,γ-Unsaturated aldehydes are obtained by a rhodium-catalyzed hydroformylation of 1,1-disubstituted allenes. For unsymmetrically 1,1-disubstituted allenes the Z-configured product is formed in up to about 95% selectivity. This is the first time that these building blocks are accessible by hydroformylation of allenes. The utility of this methodology is demonstrated by further transformations of one of the obtained products.
- K?pfer, Alexander,Breit, Bernhard
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supporting information
p. 6913 - 6917
(2015/06/08)
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- Substrate scope and stereocontrol in the Rh(II)-catalysed oxyamination of allylic carbamates
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Application of a modified Du Bois protocol for rhodium-stabilised nitrenoid generation to a variety of allylic carbamates results in 4-acetoxymethyl-1,3-oxazolidin-2-one derivatives with moderate to high levels of stereocontrol.
- Unsworth, William P.,Lamont, Scott G.,Robertson, Jeremy
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p. 7388 - 7394
(2017/09/12)
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- The first convergent total synthesis of penarolide sulfate A2, a novel α-glucosidase inhibitor
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Penarolide sulfate A2, a 31-membered macrolide encompassing a proline residue and three sulfate groups, was firstly synthesized in 16 linear steps with 4.8% overall yield. Three consecutive stereogenic centers in penarolide sulfate A2 were efficiently derived from natural chiral template l-arabinose. The crucial assembly reactions included Brown asymmetric allylation, olefin cross-metathesis, alkyne-epoxide coupling, and macrolactamization. The anti-yeast α-glucosidase activities of penarolide sulfate A2 and its fully desulfated derivative were examined showing IC50 values of 4.87 and 10.74 μg mL-1, respectively.
- Gao, Yangguang,Shan, Qiuli,Liu, Jun,Wang, Linlin,Du, Yuguo
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p. 2071 - 2079
(2014/03/21)
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- Selectivity in the addition reactions of organometallic reagents to aziridine-2-carboxaldehydes: The effects of protecting groups and substitution patterns
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Good to excellent stereoselectivity has been found in the addition reactions of Grignard and organozinc reagents to N-protected aziridine-2-carboxaldehydes. Specifically, high syn selectivity was obtained with benzyl-protected cis, tert-butyloxycarbonyl-protected trans, and tosyl-protected 2,3-disubstituted aziridine-2-carboxaldehydes. Furthermore, rate and selectivity effects of ring substituents, temperature, solvent, and Lewis acid and base modifiers were studied. The diastereomeric preference of addition is dominated by the substrate aziridines' substitution pattern and especially the electronic character and conformational preferences of the nitrogen protecting groups. To help rationalize the observed stereochemical outcomes, conformational and electronic structural analyses of a series of model systems representing the various substitution patterns have been explored by density functional calculations at the B3LYP/6-31G* level of theory with the SM8 solvation model to account for solvent effects. Grignard and bear it: Good to excellent stereoselectivity is reported for the addition reactions of Grignard and organozinc reagents to N-protected aziridine-2-carboxaldehydes (see scheme). High syn selectivity was obtained with benzyl-protected cis, tert-butyloxycarbonyl-protected trans, and tosyl-protected 2,3-disubstituted aziridine-2-carboxaldehydes. Copyright
- Kulshrestha, Aman,Schomaker, Jennifer M.,Holmes, Daniel,Staples, Richard J.,Jackson, James E.,Borhan, Babak
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supporting information; experimental part
p. 12326 - 12339
(2011/12/15)
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- Regioselective radical bromoallylation of allenes leading to 2-bromo-substituted 1,5-dienes
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The regioselective radical bromoallylation of allenes proceeded efficiently in the presence of AIBN as a radical initiator to give 2-bromo-substituted 1,5-dienes in excellent yields. The addition of a bromine radical took place regioselectively onto the central carbon of allenes generating a stable allyl radical, which underwent addition/β-fragmentation reactions with allylbromides. The products could be further functionalized by Pd-catalyzed coupling reactions.
- Kippo, Takashi,Fukuyama, Takahide,Ryu, Ilhyong
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supporting information; experimental part
p. 3864 - 3867
(2011/09/15)
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- Cleavage of benzyl ethers by triphenylphosphine hydrobromide
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Triphenylphosphine hydrobromide was found to cleave the benzyl ethers derived from 1°, 2° alkyl, and aryl alcohols to the corresponding alcohols and benzyltriphenylphosphonium bromide in good yields. Alkene and allyl phosphonium salts were produced from the benzyl ethers with 3° alkyl and allyl groups, respectively. These results indicate that the formation of the product is determined by the relative stability of the carbocationic intermediate. The anhydrous, stoichiometric amount of PPh3·HBr offers a new and effective method for the deprotection of benzyl ethers.
- Ramanathan, Mani,Hou, Duen-Ren
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experimental part
p. 6143 - 6145
(2010/12/24)
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- Synthesis of N-heterocycles, beta-amino acids, and allyl amines via aza-payne mediated reaction of ylides and hydroxy aziridines
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An ylide-based aza-Payne rearrangement of 2,3-aziridin-1-ols leads to an efficient process for the preparation of pyrrolidines. The aza-Payne rearrangement under the basic reaction conditions favors the formation of epoxy amines. Subsequent nucleophilic attack of the epoxide by the ylide yields a bis-anion, which upon a 5-exo-tet ring closure yields the desired pyrrolidine, thus completing the relay of the 3-membered the 5-membered nitrogen containing ring system. This process takes place with complete transfer of stereochemical fidelity, and can be applied to sterically hindered aziridinols.
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Page/Page column 35-36
(2009/01/23)
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- Gold(I)-catalyzed enantioselective ring expansion of allenylcyclopropanols
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(Chemical Equation Presented) The asymmetric gold(I)-catalyzed ring expansion of 1-allenylcyclopropanols is described. The method provides synthetically valuable cyclobutanones with a vinyl-substituted quaternary stereogenic center in high enantioselectivities and yields. The method shows a broad substrate scope, tolerating protected alcohols and amines, alkenes, unsaturated esters, and acetals. The reaction is easily adjustable to large-scale synthesis, leading to product formation without significant loss of selectivity or yield with only 0.5 mol% catalyst loading.
- Kleinbeck, Florian,Toste, F. Dean
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supporting information; experimental part
p. 9178 - 9179
(2009/12/06)
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- Asymmetric synthesis of α-allenylglycines
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The coupling of the homocuprate of the bislactim ether of cyclo-(-L-Val-Gly-) (9) with primary propargyl halides produces the allenyl-substituted bislactim ethers 11 in a highly diastereoselective manner, whereas the alkylation of the lith-iated bislactim ether of cyclo-(-L-Val-Gly-) yields the proparg-yl-substituted bislactim ethers 12. Subsequent hydrolysis affords, after protection of the amino group, the methyl α- allenylglycinates 15, the α-allenylglycines 16, and the methyl α-propargylglycinates 17.
- Bucuroaia, Carmen,Groth, Ulrich,Huhn, Thomas,Klinge, Michael
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experimental part
p. 3605 - 3612
(2009/12/01)
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- Diastereomerically and enantiomerically pure 2,3-disubstituted pyrrolidines from 2,3-aziridin-1-ols using a sulfoxonium ylide: A one-carbon homologative relay ring expansion
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An ylide-based aza-Payne rearrangement of 2,3-aziridin-1-ols leads to an efficient process for the preparation of pyrrolidines. The aza-Payne rearrangement under basic reaction conditions favors the formation of epoxy amines. Subsequent nucleophilic attack of the epoxide by the ylide yields a bis-anion, which upon a 5-exo-tet ring-closure yields the desired pyrrolidine, thus completing the relay of the three-membered to the five-membered nitrogen-containing ring system. This process takes place with complete transfer of stereochemical fidelity and can be applied to sterically hindered aziridinols.
- Schomaker, Jennifer M.,Bhattacharjee, Somnath,Yan, Jun,Borhan, Babak
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p. 1996 - 2003
(2007/10/03)
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- Titanocene-catalyzed regiodivergent epoxide openings
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The first regiodivergent opening of unbiased epoxides providing the ring-opened products in high enantiomeric excess from racemic and exceptionally high enantiomeric excess from enantioenriched substrates in a double asymmetric process has been devised. It constitutes a more general case of the very important enantioselective openings of meso-epoxides. Copyright
- Gansaeuer, Andreas,Fan, Chun-An,Keller, Florian,Keil, Jutta
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p. 3484 - 3485
(2008/01/01)
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- Intramolecular anionic Diels-Alder reactions of 1-aryl-4-oxahepta-1,6-diyne systems in DMSO
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Base-promoted cycloaddition reactions of 1-aryl- or 1-aryl-7-substituted-4- oxahepta-1,6-diyne systems in DMSO have proven to involve an anionic intramolecular Diels-Alder process taking place even at room temperature in spite of the reaction suffering from temporary disruption of aromaticity. Although initially formed α-arylallenide anion can be protonated by DMSO, it can be back to the allenide anion probably because of a small acidity difference between α-arylallene and DMSO. The α-arylallenide anion in combination with the α-aryl substituent can constitute an anionic diene structure that undergoes the intramolecular Diels-Alder reaction involving the C(6)-yne part, a very fast process probably because of the increased HOMO-1 level of the anionic diene, as shown by DFT calculations. Diversified substituted naphthalenes, benzofurans, phenanthrenes, and quinolines, including biaryl architectures, are available from 4-oxahepta-1,6-diynes in a highly expeditious way.
- Kudoh, Takayuki,Mori, Tomoko,Shirahama, Mitsuhito,Yamada, Masashi,Ishikawa, Teruhiko,Saito, Seiki,Kobayashi, Hisayoshi
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p. 4939 - 4947
(2008/02/03)
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- Hg(OTf)2-Catalyzed cyclization of alkynyl tert-butylcarbonate leading to cyclic enol carbonate
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Mercuric triflate was shown to be a powerful catalyst for the cyclization of alkynyl tert-butylcarbonates giving rise to cyclic enol carbonates under mild conditions. Internal alkynyl carbonate affords endo cyclization product selectively, while terminal alkynyl carbonate provides only exo cyclization product.
- Yamamoto, Hirofumi,Nishiyama, Mami,Imagawa, Hiroshi,Nishizawa, Mugio
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p. 8369 - 8373
(2007/10/03)
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- Total synthesis of microcarpalide
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An efficient, convergent approach for the total synthesis of microcarpalide (1) is described. The synthetic strategy features the Sharpless asymmetric dihydroxylation, regioselective epoxide opening with various nucleophiles such as a lithium acetylide and cuprates derived from the vinyl stannane and the vinyl iodide for the construction of a C7-C8 trans-double bond and Yamaguchi macrolactonization as the key steps.
- Kumar, Pradeep,Naidu, S. Vasudeva
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p. 4207 - 4210
(2007/10/03)
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- Preparation and cancer cell invasion inhibitory effects of C16-alkynic fatty acids.
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Five C(16)-alkynic fatty acids (2-6) were prepared and examined their inhibitory effects on cancer cell invasion. It has been found that hexadeca-6,8,10-triynoic acid (5) and hexadeca-8,10,12-triynoic acid (6) exhibit similar potent inhibitory activities with that of octadeca-8,10,12-triynoic acid (1) which was isolated from Scurrula atropurpurea (Loranthaceae).
- Ohashi, Kazuyoshi,Winarno, Hendig,Mukai, Mutsuko,Shibuya, Hirotaka
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p. 463 - 466
(2007/10/03)
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- Study of the regioselectivity in the hydrotelluration of hydroxy alkynes
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Vinylic tellurides were synthesized by the addition of organotellurols to acetylenic alcohols and the regioselectivity of the reaction was evaluated.
- Stefani, Hélio A.,Cardoso, Lincoln D. G.,Valduga, Claudéte J.,Zeni, Gilson
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p. 167 - 172
(2007/10/03)
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- Synthesis of polyacetylenic acids isolated from Heisteria acuminata
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matrix presented Four linear polyacetylenic compounds were synthesized. Pentadeca-6,8,10-triynoic acid 1 and octadeca-8,10,12-triynoic acid 2 were synthesized by using acetylene coupling reactions. The syntheses of (Z)-hexadec-11-en-7,9-diynoic acid 3 and (Z)-octadec-12-en-7,9-diynoic acid 4 by using vinylic telluride coupling reactions were accomplished.
- Zeni, Gilson,Panatieri, Rodrigo B.,Lissner, Eliseo,Menezes, Paulo H.,Braga, Antonio L.,Stefani, Helio A.
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p. 819 - 820
(2007/10/03)
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- Synthesis of polyacetylenic montiporic acids A and B
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The synthesis of two polyacetylenic acids, montiporic A and B is reported.
- Stefani, Helio A.,Costa, Iguatemi M.,Zeni, Gilson
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p. 9215 - 9217
(2007/10/03)
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- New type formation of 1,3-enynes (or internal alkynes) via coupling of organoboranes with alkynylcopper compounds mediated by copper(II)
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The copper(II) - mediated coupling reaction of alkenyl-dialkyl- or trialkyl-boranes with alkynylcopper compounds (generated in situ), in the presence of appropriate solvents and a small amount of water, gives (E)-1,3-enynes (or disubstituted alkynes) with various functional groups in reasonable yields.
- Masuda, Yuzuru,Murata, Miki,Sato, Kaname,Watanabe, Shinji
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p. 807 - 808
(2007/10/03)
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- (Carboxyalkyl)benzyl propargyl ethers as selective inhibitors of leukocyte-type 12-lipoxygenases
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A series of (carboxyalkyl)benzyl propargyl ethers was synthesized and tested as inhibitors of 12-lipoxygenase (12-LO) from porcine leukocyte cytosol. Optimum activity was displayed by 3-[4-[(2- tridecynyloxy)methyl]phenyl]propanoic acid. Altering the length of the alkyl side chain attached to the acetylenic group reduced activity. Changing the substitution pattern in the (carboxyalkyl)benzyl group from para to meta or ortho also reduced activity. Analogs in which the triple bond was replaced by a double bond or an allene displayed reduced activity, whereas fully saturated analogs were inactive. High concentrations (10 μM) of the most potent acetylenic (carboxylalkyl)benzyl ethers did not inhibit human platelet 12-LO, human neutrophil 5-LO, rabbit reticulocyte 15-LO, or soybean 15-LO. Thus, this class of compounds represents the first example of isoform specific LO inhibitors.
- Gorins, Gilles,Kuhnert, Lethea,Johnson, Carl R.,Marnett, Lawrence J.
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p. 4871 - 4878
(2007/10/03)
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- Total synthesis of (15S, 16R, 19S, 20R, 34S)-diepomuricanin
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An eleven-step reaction sequencing starting from enantiomerically pure (-)-muricatacin (6) afforded the key intermediate 12, which was then converted to (15S, 16R, 19S, 20R, 34S)-diepomuricanin (1) via introduction of an acetylene unit and a coupling reaction with iodo lactone synthon 15.
- Konno, Hiroyuki,Makabe, Hidefumi,Tanaka, Akira,Oritani, Takayuki
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p. 5393 - 5396
(2007/10/03)
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- An expeditious synthesis of alk-2-yn-1-ols
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A convenient inexpensive preparation of alk-2-yn-1-ols, commencing from terminal alkynes, has been developed. This procedure allows for using paraformaldehyde instead of gaseous formaldehyde for hydroxymethylation of alk-1-ynylmagnesium bromides.
- Zwierzak, Andrzej,Tomassy, Beata
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p. 3593 - 3600
(2007/10/03)
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- A Practical Synthesis of the Khapra Beetle Pheromones
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A practical synthesis of the title pheromones is described.The features of the synthesis include high optical purities of the target compounds, utilization of easy accessible materials and employment of operationally simple and facile reactions.Key Words: Khapra beetle / Pheromones / Trogoderma granarium / 8-Hexadecenal, (14R)-14-methyl-
- Pawar, Archana S.,Chattopadhyay, Subrata,Mamdapur, Vasant R.
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p. 445 - 446
(2007/10/02)
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- Synthesis of α-acetylenic aldehydes from 2-acetylenic phenyl sulfides
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Monochlorination at the 1 position, with sulfuryl chloride, followed by hydrolysis converted 2-acetylenic phenyl sulfides into 2-acetylenic aldehydes.
- Fortes,Garrote
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p. 2869 - 2877
(2007/10/02)
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- Synthesis of (Z)-2-nonenyl propionate, an erroneously identified insect pheromone component of flour beetle, Tribolium castaneum
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Propargyl alcohol is alkylated to give acetylene 1, which on cis-hydrogenation over P2-Ni followed by esterification with propionyl chloride affords the title compound (I).
- Subbaraman, A S,Mithran, S,Mamdapur, V R
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p. 511 - 512
(2007/10/02)
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- Chemistry of Fruit Flies. Composition of the Rectal Gland Secretion of (Male) Dacus cucumis (Cucumber Fly) and Dacus halfordiae. Characterization of (Z,Z)-2,8-Dimethyl-1,7-dioxaspiroundecane
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Combined gas chromatography-mass spectrometry and synthesis have established that the major components of the rectal gland secretion of adult male cucumber flies (Dacus cucumis) are the E,E, E,Z, and Z,Z diastereomers of 2,8-dimethyl-1,7-dioxaspiroundecane, which have been synthesized utilizing organomercury chemistry from 1,10-undecadien-6-one.The thermodynamically least stable Z,Z diastereomer has been characterized for the first time, by 1H and 13C NMR measurements and mass spectrometry.Minor amounts of 3-hydroxy-2,8-dimethyl-1,7-dioxaspiroundecane and various derivatives of the 1,6-dioxaspirodecane and 1,7-dioxaspirododecane systems are also present. 1,3-Nonanediol occurs in significant amounts, and both enantiomers have been acquired by Sharpless asymmetric epoxidation of (E)-2-nonen-1-ol followed by Red-Al (Aldrich) reduction of the chiral epoxy alcohols.Chiral gas chromatographic analysis of the diols (as their cyclic carbonates) has demonstrated that the natural material is the R-(-) enantiomer.Natural (E,Z)-2,8-dimethyl-1,7-dioxaspiroundecane is shown to be racemic, whereas the more abundant E,E diastereomer is enantiomerically highly pure, possessing the 2S,6R,8S configuration.The major volatile component of the rectal gland secretion of male Dacus halfordiae (Tryon) is also (E,E)-2,8-dimethyl-1,7-dioxaspiroundecane, with no detectable levels of the E,Z or Z,Z isomers.Other spiroacetals present were 2-ethyl-7-methyl-1,6-dioxaspirodecane and the unusual even carbon-numbered (E,E)-2-ethyl-8-methyl-1,7-dioxaspiroundecane. 6-Oxo-1-nonanol, diethyl succinate, and 2-methyl-6-pentyl-3,4-dihydro-2H-pyran were also identified.
- Kitching, William,Lewis, Judith A.,Perkins, Michael V.,Drew, Richard,Moore, Christopher J.,et al.
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p. 3893 - 3902
(2007/10/02)
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- Arachidonic acid analogs
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Long chain unsaturated hydrocarbon derivatives, having from 13 to 21 carbon atoms, which are substituted at the 1-position by a phenoxy, phenylthio or a phenyl that bear a carboxylic acid group at the ortho, meta or para positions, and up to 4 carbon-carbon triple bonds, methods of preparing them, and pharmaceutical preparations containing them. These compounds are useful as lipoxygenase inhibitors, and therefore as antiinflammatory agents.
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- Synthesis of the optical antipodes of 4-alkyl-γ-lactones
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Optical antipodes of 4-alkyl-γ-lactones 3 have been prepared by photochemical rearrangement of optically active α,β-epoxy diazomethyl ketones 1 in ethanol to give 4-hydroxy-alkenoates 2, followed by reduction of the alkene bond and subsequent lactonization.The required epoxy diazomethyl ketones 1 were obtained via the following sequence of reactions: alkylation of 2-propyn-1-ol, subsequent reduction to the alkenols 6, Sharpless epoxidation to 2,3-epoxy alcohols 7, oxidation to glycidic esters 8 and finally conversion to diazo ketones 1.The enantiomeric purities range from 84 to 100percent.
- Thijs, Lambertus,Waanders, Peter P.,Stokkingreef, Edwin H. M.,Zwanenburg, Binne
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p. 332 - 337
(2007/10/02)
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- Synthesis of (Z)-7-Nonadecen-11-one and (Z)-7-Eicosen-11-one, Sex Pheromone Components of Peach Fruit Moth, Carposina noponensis Walsingham
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Catalytic hydrogenation of 2-nonyn-1-ol (III) in the presence of Lindlar's catalyst provides (Z)-2-nonen-1-ol (IV) which on bromination followed by alkylation with ethyl monosodiomalonate furnishes the diester (VI).Decarbethoxylation of VI with NaCl/DMSO to monoester (VII), followed by LAH reduction, yields the carbinol (VIII) which on treatment with Corey's reagent gives the aldehyde (IX) in good yield.Aldehyde (IX) on Grignard reaction with 1-bromooctane and 1-bromononane separately provides the alcohols (X) and (XI), respectively.The alcohols (X) and (XI) on oxidation with Corey's reagent yield the title ketones, (Z)-7-nonadecen-11-one (I) and (Z)-eicosen-11-one (II), respectively.
- Vig, O. P.,Sharma, M. L.,Taneja, K. C.,Malik, Neera
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p. 863 - 865
(2007/10/02)
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- A NEW SYNTHETIC METHOD FOR PELLITORINE
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A stereoselective synthesis of N-isobutyl-E,E-2,4-decadienamide, so called pellitorine is described in which the elimination reaction of acetic acid from 2-acetoxy-E-3-decenenitrile providing 2,4-decadienenitrile in a high yield was used as a key reaction.
- Mandai, Tadakatsu,Gotoh, Jiso,Otera, Junzo,Kawada, Mikio
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p. 313 - 314
(2007/10/02)
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