- Total synthesis of lipoxin A4 and lipoxin B4 from butadiene
-
The total synthesis of LXA4 and LXB4 has been achieved starting from butadiene via palladium catalyzed telomerization. Sharpless catalytic AE and C-2 inversion of the 2(S),3(S)-epoxy alcohols, using Myers CO2/Cs2CO3 procedure, generated the asymmetric centers. The flexibility of the strategy allows an easy access to the linear eicosanoids. (C) 2000 Elsevier Science Ltd.
- Rodríguez,Nomen,Spur,Godfroid,Lee
-
-
Read Online
- Gold-Catalyzed Synthesis of Chiral Cyclopentadienyl Esters via Chirality Transfer
-
Efficient access to chiral cyclopentadienyl esters from readily accessible chiral enynyl ester substrates is developed. Typically high levels of chirality transfer realized in this homogeneous gold catalysis are attributed to the intermediacy of a chiral bent allene gold complex. Cyclopentadienyl esters can be prepared in good yields and with excellent enantiomeric excesses. The synthetic utilities of the chiral cyclopentadienyl esters are demonstrated by the Diels-Alder reactions, fluorination, alkylation, and epoxidation without any notable erosion of enantiopurity.
- Zhao, Ke,Hsu, Yu-Chen,Yang, Ziguang,Liu, Rai-Shung,Zhang, Liming
-
supporting information
p. 6500 - 6504
(2020/09/02)
-
- A general strategy toward the total synthesis of C17 polyacetylenes virols A and C
-
A general strategy toward the total synthesis of biologically important C17 polyacetylenes family such as virols A and C has been developed, which employed the (R, R)-ProPhenol/Zn complex-catalyzed highly stereoselective direct addition of propiolate to aliphatic aldehydes as the key step for constructing chiral (S)-alkynol units. Besides, chiral alkynol units in other C17 polyacetylenes were also synthesized based on the protocol developed.
- Liu, Jia,Li, Hong-Lian,Guo, Xian-Ru,Zhou, Lin,Wang, Yi,Duan, Ya-Nan,Wang, Mei-Zi,Na, Ri-Song,Yu, Bin
-
p. 6603 - 6610
(2016/09/28)
-
- Synthetic method for (S)-Virol A from water hemlock extract
-
The invention relates to a synthetic method for (S)-Virol A from a polyacetylene water hemlock extract. The synthetic method for (S)-Virol A from the polyacetylene water hemlock extract is an asymmetric synthetic method, and comprises the following steps: firstly, under catalysis of a chiral ligand, methyl propiolate and dimethyl zinc are reacted to prepare an alkynyl zinc reagent, hexanal is subjected to asymmetric addition reaction to obtain a chiral intermediate (S)-4- hydroxy-2-alkyne methyl nonanoate, through ester group removal to obtain acetylene, the processed intermediate is coupled with vinylidene chloride, then selective reduction is carried out to obtain a product, and finally the product is coupled with 4,6-diyne-1-heptanol to obtain the (S)-Virol A. The flow of the method is simple and easy to realize, and the method is environmental-friendly.
- -
-
Paragraph 0031; 0032; 0033
(2016/10/07)
-
- Coupling biocatalysis and click chemistry: One-pot two-step convergent synthesis of enantioenriched 1,2,3-triazole-derived diols
-
A fully convergent one-pot two-step synthesis of different chiral 1,2,3-triazole-derived diols in high yields and excellent enantio- and diastereoselectivities has been achieved under very mild conditions in aqueous medium by combining a single alcohol dehydrogenase (ADH) with a Cu-catalysed 'click' reaction. The Royal Society of Chemistry 2013.
- Cuetos, Aníbal,Bisogno, Fabricio R.,Lavandera, Iván,Gotor, Vicente
-
p. 2625 - 2627
(2013/04/23)
-
- One-pot deracemization of sec-alcohols: Enantioconvergent enzymatic hydrolysis of alkyl sulfates using stereocomplementary sulfatases
-
Hand in hand: The title transformation was achieved using a pair of sulfatases acting through inversion and retention of configuration on opposite substrate enantiomers. Using Pseudomonas aeruginosa arylsulfatase PAS with alkylsulfatase PISA1 in one-pot l
- Schober, Markus,Toesch, Michael,Knaus, Tanja,Strohmeier, Gernot A.,Van Loo, Bert,Fuchs, Michael,Hollfelder, Florian,Macheroux, Peter,Faber, Kurt
-
p. 3277 - 3279
(2013/04/23)
-
- Novel, stereoselective and stereospecific synthesis of allenylphosphonates and related compounds via palladium-catalyzed propargylic substitution
-
We have developed a novel method for the synthesis of allenylphosphonates and related compounds based on a palladium(0)-catalyzed reaction of propargylic derivatives with H-phosphonate, H-phosphonothioate, H-phosphonoselenoate, and H-phosphinate esters. The reaction is stereoselective and stereospecific, and provides a convenient entry to a vast array of allenylphosphonates and their analogues with diverse substitution patterns in the allenic moiety and at the phosphorus center. Some mechanistic aspects of this new reaction were also investigated. Copyright
- Kalek, Marcin,Stawinski, Jacek
-
p. 1741 - 1755
(2011/09/15)
-
- Palladium-catalyzed propargylic substitution with phosphorus nucleophiles: Efficient, stereoselective synthesis of allenylphosphonates and related compounds
-
A new, efficient method is developed, based on a palladium(0)-catalyzed reaction of propargylic derivatives with various phosphorus nucleophiles, to produce allenylphosphonates and their analogues with defined stereochemistry in the allenic and the phosph
- Kalek, Marcin,Johansson, Tommy,Jezowska, Martina,Stawinski, Jacek
-
supporting information; experimental part
p. 4702 - 4704
(2011/02/19)
-
- Total synthesis of halicholactone and neohalicholactone
-
New total syntheses of the marine oxylipins halicholactone and neohalicholactone are presented. The key building blocks were synthesized utilizing chemoenzymatic methods.
- Bischop, Martina,Doum, Verena,Nordschild Nee Rieche, Anja C. M.,Pietruszka, Joerg,Sandkuhl, Diana
-
experimental part
p. 527 - 537
(2010/06/16)
-
- Kinetic resolution of propargylic alcohols catalyzed by benzotetramisole
-
(Chemical Equation Presented) Kinetic resolution of variously substituted secondary propargylic alcohols catalyzed by benzotetramisole (BTM) proceeds with selectivity factors up to 32, the highest ever achieved with nonenzymatic catalysts for this class o
- Birman, Vladimir B.,Guo, Lei
-
p. 4859 - 4861
(2007/10/03)
-
- Synthesis and use of stereospecifically deuterated analogues of palmitic acid to investigate the stereochemical course of the Δ11 desaturase of the processionary moth
-
Thaumetopoea pityocampa pheromone glands contain desaturases that, after several sequential reactions from palmitic acid, catalyze the formation of a unique enyne fatty acid, which is the immediate sex pheromone precursor. In this article, we describe the synthesis of different stereospecifically deuterium-labeled and isotopically tagged palmitic acid probes needed to decipher the stereochemical course of the T. pityocampa Δ11 desaturase. The synthesis of probes has been carried out by a chemoenzymatic route, in which the key step is the kinetic lipase-catalyzed resolution of racemic mixtures of secondary propargyl alcohols. The presence of the acetylenic bond simplifies the absolute configuration determination of the resolved alcohols. Moreover, it allows the introduction of the isotopic tag by deuteration. By use of the probes thus prepared, experimental evidence is presented that the Δ11 desaturase of T. pityocampa transforms palmitic acid into (Z)-11-hexadecenoic acid by removal of the pro-(R)-hydrogen atoms from both C11 and C12.
- Abad, Jose-Luis,Villorbina, Gemma,Fabrias, Gemma,Camps, Francisco
-
p. 7108 - 7113
(2007/10/03)
-
- Enantioselective cathodic reduction of some prochiral ketones in the presence of (-)-N,N′-dimethylquininium tetrafluoroborate at mercury cathode
-
This work describes preparative scale enantioselective cathodic reduction of some prochiral ketones, viz. 3,4-dihydro-1(2H)-naphthaleneone, 2-octanone, 1-phenyl-2-propanone, E-3-octen-2-one, 1-octyn-3-one, 1-undecyn-3-one, 1-tetradecyn-3-one at mercury pool in N,N-dimethyl formamide (DMF)-2-propanol (9.5:0.5), using tetrabutylammonium tetrafluoroborate (TBA·BF4), as supporting electrolyte and (-)-N,N′-dimethylquininium tetrafluoroborate (DMQ·2BF4), as a enantioselective inductor. The products obtained were corresponding (S)-alcohols in 24-70% ee.
- Yadav, Ashok K.,Manju, Meera,Chhinpa, Pukh Raj
-
p. 1079 - 1081
(2007/10/03)
-
- Novel chemoenzymatic strategy for the synthesis of enantiomerically pure secondary alcohols with sterically similar substituents
-
A novel chemoenzymatic strategy for the synthesis of enantiomerically pure secondary alcohols with sterically similar substituents is described. The key step is the kinetic lipase-catalyzed resolution of racemic mixtures of substituted propargylic alcohols. The efficiency of this new approach was tested in the preparation of the corresponding enantiomers of 1,11-hexadecandiol derivatives ((R)-5 and (S)-5). Two strategies were tested. In the first one, the racemic intermediate 1-octyn-3-ol (1) was resolved enzymatically and then elongated with 1-bromo-9,11-dioxadodecane. Alternatively, the racemic 1 can be elongated to the corresponding racemic 17,19-dioxa-7-eicosyn-6-ol (3) first and then resolved biocatalytically. Twelve commercially available lipases were screened for the kinetic resolution of these intermediates. Among them, Candida antarctica lipase (CAL-B) and Humicola lanuginosa lipase (HLL) were the best biocatalysts for the resolution of 1 (S enantiomer 90% ee, E = 35), and 3 (R enantiomer 90% ee, E = 34), respectively.
- Abad, Jose-Luis,Soldevila, Carles,Camps, Francisco,Clapes, Pere
-
p. 5351 - 5356
(2007/10/03)
-
- Preparation of optically pure propargylic and allylic alcohols from 2-(trimethylsilyl)vinyl sulfoxides as a chiral ethynyl anion synthon: Computational studies on elimination reaction of 2-(trimethylsilyl)vinyl sulfoxides
-
The reaction of the (α-carbanion derived from (trimethylsilyl)vinyl sulfoxides with aldehydes afforded a diastereomeric mixture of the products. Each diastereomer was subjected to specific elimination reactions to give optically pure propargylic, trimethylsilylated propargylic, and allylic alcohols. Acceleration of the sulfenic acid-elimination from the β-silylvinyl sulfoxide was demonstrated by the ab initio calculation to be ascribed mainly to the β-effect of the silyl group.
- Nakamura, Shuichi,Kusuda, Shinya,Kawamura, Kiyoshi,Toru, Takeshi
-
p. 640 - 647
(2007/10/03)
-
- The effect of catechin derivatives on the enantioselectivity of lipase-catalyzed hydrolyses of alkynol benzoate esters
-
Polyphenols, such as (+)-catechin and pyrogallol could be used to enhance stereochemical control in the lipase-catalyzed hydrolysis of alkynol benzoate esters, leading to increased enantioselectivities in the kinetic resolution of alkynols with lipase Amano AH.
- Nakamura, Kaoru,Takenaka, Keishi
-
p. 415 - 422
(2007/10/03)
-
- Enantioselective synthesis of both enantiomers of various propargylic alcohols by use of two oxidoreductases
-
The oxidoreductases Lactobacillus brevis alcohol dehydrogenase (LBADH) and Candida parapsilosis carbonyl reductase (CPCR) are suitable catalysts for the reduction of ketones to afford enantiopure sec. alcohols. A broad variety of alkynones (1, 3, and 5) are accepted as substrates and the corresponding propargylic alcohols (2, 4, and 6) are obtained in good yield and excellent enantiomeric excess. By changing the steric demand of the substituents the ee values can be adjusted and even the configurations of the products can be altered.
- Schubert, Thomas,Hummel, Werner,Kula, Maria-Regina,Mueller, Michael
-
p. 4181 - 4187
(2007/10/03)
-
- Convenient Enzymatic Resolution of Alcohols Using Highly Reactive, Nonharmful Acyl Donors, 1-Ethoxyvinyl Esters
-
1-Ethoxyvinyl esters 3, a new type of acyl donors for enzymatic resolution of racemic alcohols, were disclosed to be superior to the contemporary major reagents, vinyl esters 1 and isopropenyl esters 2. Three features of 3 are noticeable: (1) 3 generates ethyl acetate as a single coproduct, which does not affect any enzymes, while acetaldehyde liberated from 1 deactivates some kinds of lipases. (2) The reactivity of 3 was not less than that of 1 and much higher than that of 2, and the optical purity of the products was as high as that of 1 and 2. Especially, it was generally observed that 3 showed higher reactivity than 1 for reactions using Candida rugosa lipases, one of the most commonly employed lipases, having liberal applicability to substrates but sensitive to acetaldehyde. Twelve examples of the kinetic resolution of racemic secondary alcohols (5 and 10) and one desymmetrization of meso-alcohol 7 were presented employing the acetate 3a or the octanoate 3b and four types of lipases. (3) A one-pot procedure for the preparation of 3 from the corresponding carboxylic acid and the subsequent enzymatic resolution of alcohols, which has not been reported using 1 or 2, was elucidated. The chemical and optical yields of the products by this procedure were similar to those obtained using isolated 3.
- Kita, Yasuyuki,Takebe, Yasushi,Murata, Kenji,Naka, Tadaatsu,Akai, Shuji
-
-
- Optically active propargylic and allylic alcohols with a difluoromethyl group at the terminal carbon
-
Enantioselective esterification of α-substituted propargylic alcohols was found to proceed very smoothly in the presence of a catalytic amount of lipase (Nobozym 435) to yield the corresponding (R)-alcohols and (S)-acetates with high enantiomeric excess. Further, the preparation of optically active propargylic and allylic alcohols with a difluoromethyl group at the terminal carbon is described.
- Xiao, Ling,Kitazume, Tomoya
-
p. 3597 - 3601
(2007/10/03)
-
- Reduction of Ketones with LiAlH4 Complexes of α,α,α′,α′-Tetraaryl-1,3-dioxolane-4,5- dimethanols (TADDOLs): A Combination of Enantioselective Reduction and Clathrate Formation with a Discussion of LAH Reagents Bearing C2-Symmetrical Ligands
-
A complex prepared from one equivalent each of LiAlH4, EtOH and a TADDOL (α,α,α′,α′-tetraaryl-1,3-dioxolane-4,5- dimethanol) reduces aryl alkyl ketones to sec. alcohols with enantiomer ratios (er) up to 96:4. The chiral LAH derivative is used in two-fold excess in THF solution and at dry ice temperatures. The ability of TADDOLs to form clathrates diastereoselectively can be exploited to increase the er of the initially formed alcohols by a simple modification of the work-up procedure and hence, products of very high enantiopurity (er 99:1) can be isolated. When (R,R)-TADDOLs (from (R,R)-tartrate) are applied in the reaction, the 1-aryl-alkanols formed preferentially have (S) configuration, as for the products obtained with the corresponding (P)-BINOL and (P)-BIPHENOL derivatives. A common mechanistic model is discussed.
- Seebach, Dieter,Beck, Albert K.,Dahinden, Robert,Hoffmann, Matthias,Kuehnle, Florian N. M.
-
p. 459 - 484
(2007/10/03)
-
- Practical preparation of both optically pure enantiomers of but-1-yn-3-ol, oct-1-yn-3-ol and 6-methylhept-2-yn-4-ol using biocartol as resolving agent
-
A new facile preparation of optically pure secondary alkynols has been developed. This involves resolution of the corresponding racemic alcohols using biocartol as the resolving agent.
- Michelet,Besnier,Tanier,Touzin,Genet,Demoute
-
p. 165 - 167
(2007/10/02)
-
- SYNTHESIS OF OPTICALLY PURE ALKYNOLS
-
(R,S)-1-alkylprop-2-yn-1-ols have been separated by a 2-step procedure, esterification with N-p-tosyl-(L)-phenylalanine (or valine), recrystallisation of the diastereomeric esters from ethanol/hexane and saponification of the optically pure esters.
- Kuenstler, Th.,Schollmeyer, D.,Singer, H.,Steigerwald, H.
-
p. 1645 - 1650
(2007/10/02)
-
- A convenient chiral synthesis of 4-alkyl-γ-butanolides
-
A simple three step synthesis of 4-alkyl-γ-butanolides as flavoring compounds from chiral propargyl alcohols is described.
- Yadav,Maniyan
-
p. 2731 - 2741
(2007/10/02)
-
- Convenient Preparation of Optically Pure Propargylic Alcohols Using 2-(Trimethylsilyl)vinyl Sulfoxide As A Novel Chiral Synthon
-
Both enentiomers of optically pure propargylic alcohols are conveniently prepared by the reaction of α-vinyl anion of 2-(trimethylsilyl)vinyl p-tolyl sulfoxide with aldehydes and subsequent either desilylsulfination or thermal elimination of the sulfinyl group.
- Kusuda, Shinya,Kawamura, Kiyoshi,Ueno, Yoshio,Toru, Takeshi
-
p. 6587 - 6590
(2007/10/02)
-
- A Lipase Mediated Asymmetric Hydrolysis of 3-Acyloxy-1-octynes and 3-(E)-Acyloxy-1-octenes
-
Optical resolution of 3-propionyloxy-1-trimethylsilyl-1-octyne or 3-(E)-propionyloxy-1-octene via lipase-mediated hydrolysis gave optically pure (S)-1-trimethylsilyl-1-octyn-3-ol and (R)-(E)-1-iodo-1-octen-3-ol, respectively, in which a reversal of enantio-selectivity for hydrolysis was observed between 3-propionyloxy-1-octyn and its 1-trimethylsilylated derivative, and the effect of the acyl groups on the enantio-discrimination was also investigated.
- Shimizu, Makoto,Kawanami, Hiroshi,Fujisawa, Tamotsu
-
p. 107 - 110
(2007/10/02)
-
- Stereoselective synthesis of (S)-13-hydroxy octadeca-(9Z, 11E)-di- and (9Z, 11E, 15Z)-trienoic acids: Selfdefensive substances against rice blast disease
-
A highly stereoselective synthesis of [(S)-coriolic acid] (1) and first total synthesis of (S)-15,16-didehydrocoriolic acid (2) by a Pd°-CuI catalysed coupling of (S )-halovinylalcohol with acetylenic moiety is described. The required optically pure chlor
- Yadav,Deshpande,Sharma
-
p. 4465 - 4474
(2007/10/02)
-
- Synthesis of a novel four-carbon chiron - (R)-1-t-butyldimethylsilyl-3,4-epoxy-but-1-yne
-
A simple and efficient synthesis of the novel chiron-(R)-1-TBDMS-3,4-epoxy-but-1-yne has been developed starting from a derivative of (R,R)-(-)-tartaric acid. A new stereoselective bromination reaction of an O-silyl ether with BBr3 is also described.
- Lopp,Kanger,Muraus,Pehk,Lille
-
p. 943 - 944
(2007/10/02)
-
- A practical access to optically pure (S)-1-octyn-3-ol
-
A highly efficient resolution of (±)-1-octyn-3-ol through recrystallization of the diastereomeric esters has been achieved by using N-(p-toluenesulfonyl)-(S)-phenylalanyl chloride as resolving reagent. The method provides a facile and economical entry to
- Hashimoto,Kase,Suzuki,Yanagiya,Ikegami
-
p. 833 - 839
(2007/10/02)
-
- Catalytic Asymmetric Synthesis of Optically Active Alkynyl Alcohols by Enantioselective Alkynylation of Aldehydes and by Enantioselective Alkylation of Alkynyl Aldehydes
-
Catalytic asymmetric synthesis of optically active secondary alkynyl alcohols (1) by enantioselective addition of organozinc reagents to aldehydes in the presence of a small amount of catalyst was examined.Enantioslective alkynylation of benzaldehyde by a
- Niwa, Seiji,Soai, Kenso
-
p. 937 - 943
(2007/10/02)
-
- ENZYMATIC RECOGNITION OF DIASTEREOMERIC ESTERS
-
Aiming to improve the enantioselectivity of enzymatic resolution of esters, lipase catalyzed hydrolysis of (D)- and (L)-2-chloropropanoates of four racemic alcohols and transesterification of ethyl (DL)-2-chloropropanoate with optically pure alcohols was investigated.Thus, (rac)-endo-2-norbornyl (L)-2-chloropropanoate was hydrolized by lipase P about 5 times more selectively than its corresponding (D)-counterpart and optically pure (1R,2S,5R)-menthol was obtained by transesterification of its racemate with ethyl (D)-2-chloropropanoate using Candida cylindracea (CC)lipase.From the results obtained it seems obvious that lipases CC and P mainly can recognize the chirality of an alcohol moiety rather than that of an acid
- Rabiller, C. G.,Koenigsberger, .,Faber, K.,Griengl, H.
-
p. 4231 - 4240
(2007/10/02)
-
- PRACTICAL SYNTHESIS OF (S)-1-OCTYN-3-OL: A KEY INTERMEDIATE FOR THE PROSTAGLANDIN SYNTHESIS
-
Practical synthesis of (S)-octyn-3-ol is devised starting from (2S,3S)-2,3-O-isopropylidenedioxyoctanol readily accessible from diethyl (L)-tartrate.
- Takano, Seiichi,Sugihara, Takumichi,Ogasawara, Kunio
-
p. 1721 - 1725
(2007/10/02)
-
- Base induced opening of 2,3-epoxychlorides: An efficient preparation of trans-chlorovlnyl alcohols
-
A highly efficient protocol for the sythesis of of chiral trans-1-chlorvinyl alcohols (2) from chiral 2,3-epoxychloride is described by using stoicheiometric amount of LiNH2 or LDA.
- Yada,Deshpande, Prasad K.,Sharma
-
p. 4495 - 4496
(2007/10/02)
-
- Selective Reductions. 46. Effect of the Steric Requirement at the 2-Position of Apopinene on chiral Reductions. B-(Iso-2-ethylapopinocampheyl)- and B-(Iso-2-n-propylapopinocampheyl)-9-borabicyclononanes as Improved Reagents for the Chiral Reduction of α,β-Acetylenic Ketones ...
-
B-(Iso-2-ethylapopinocampheyl)-9-borabicyclononane (Eapine-Borane, 7), and B-(Iso-2-n-propylapopinocampheyl)-9-borabicyclononane (Prapine-Borane, 9), prepared via the hydroboration of 2-ethylapopinene (6) or 2-n-propylapopinene (8), respectively, with 9-borabicyclononane, reduce prochiral α,β-acetylenic ketones and α-keto esters to the corresponding alcohols with significantly higher optical induction than does Alpine-Borane (1). (-)-2-n-Propylapopinene was synthesized by treating nopyl tosylate with dimethyl cuprate prepared in situ from methyllithium and cuprous iodide. (+)-2-n-Propylapopinene was synthesized by Schlosser metalation of (+)-α-pinene followed by treatment with ethyl iodide. 4-Phenyl-3-butyne-2-one was reduced to the corresponding propargylic alcohol in 89percent ee and 96percent ee by Eapine-Borane and Prapine-Borane, respectively, as compared to 82percent ee with Alpine-Borane.Similar improved results were realized in the reduction of other acetylenic ketones by Eapine-Borane and Prapine-Borane.Similar improvements in the optical yields were realized in the reduction of α-keto esters by Eapine-Borane.For example, while Alpine-Borane produced methyl and ethyl lactate in 92percent and 91percent ee, respectively, Eapine-Borane gave these alcohols in 97percent and 96percent ee, respectively.Unfortunately, Prapine-Borane shows no improvement in percent ee for the reduction of α-keto esters.The increase in the percent ee realized is tentatively attributed to the increased steric requirements of the alkyl group at the 2-position of apopinene.
- Brown, Herbert C.,Ramachandran, P. Veeraraghavan,Weissman, Steven A.,Swaminathan, S.
-
p. 6328 - 6333
(2007/10/02)
-
- Coupling Reactions of 1-Tributylstannyl-1-octen-3-ol Catalyzed by Palladium: The Synthesis of PGB1 and Coriolic Acid
-
The palladium catalyzed coupling of (S)-E-1-tributylstannyl-1-octen-3-ol (3) with 2-(6-carbethoxyhexyl)-3-iodo-2-cyclopenten-1-one gave a 70percent yield of the (S)-ethyl ester of PGB1.Coriolic acid was synthesized in 75percent yield by coupling 3 with Z-10-iododecenoic acid, demonstrating the tolerance of this coupling reaction to the carboxylic acid function.
- Stille, J.K.,Sweet, Mark P.
-
p. 3645 - 3648
(2007/10/02)
-
- PRACTICAL METHOD FOR SYNTHESIS OF OPTICALLY PURE PROPARGYLIC ALCOHOLS
-
Highly efficient practical method for synthesis of optically pure propargylic alcohols is described which involves the synthesis of chiral γ-iodo allylic alcohols by the Sharpless kinetic resolution of secondary γ-hetero substituted allylic alcohols and their 1,2-dehydrohalogenation reaction.
- Ito, Takayori,Okamoto, Sentaro,Sato, Fumie
-
p. 7083 - 7086
(2007/10/02)
-
- Organopalladium Approaches to Prostaglandins. 6. Synthesis of Interphenylene Prostaglandin Endoperoxide Analogs Via Benzylpalladation of Bicyclic Alkenes.
-
The reactions of norbornene, norbornadiene and 7-oxanorbornene with methyl 3-(chloromethyl)phenoxyacetate (4), optically pure (S)-1-octyn-3-ol (5), and 8percent Pd(PPh3)4 afford in one step satisfactory yields of the corresponding esters 6, 7 and 8 respectively, readily saponified to the first interphenylene prostaglandin endoperoxide analogs 10, 11 and 12 respectively.
- Larock, Richard C.,Babu, Srinivasan
-
p. 2013 - 2020
(2007/10/02)
-
- ENENTIOSELECTIVE HYDROLYSES BY BAKER'S YEAST - III. MICROBIAL RESOLUTION OF ALKYNYL ESTERS USING LYOPHILIZED YEAST
-
Both enantiomers of optically active 1-alkyn-3-ols were obtained in high optical purity by microbial resolution of their racemic acetate using a stable ready-to-use lyophilized yeast preparation.
- Glaenzer, B. I.,Faber, K.,Griengl, H.
-
p. 5791 - 5796
(2007/10/02)
-
- ASYMMETRIC REDUCTIONS OF PROPARGYL KETONESAN EFFECTIVE APPROACH TO THE SYNTHESIS OF OPTICALLY-ACTIVE COMPOUNDS
-
Propargyl ketones are readily reduced by the asymmetric reducing agent B-3-pinanyl-9-borabicyclo-nonane (Alpine-borane).The reagent prepared from (+)-α-pinene and 9-BBN provides the R enantiomer while the S enantiomer can be obtained from (-)-α-pinene.Alternatively the S enantiomer ca be prepared from the reagent derived from 9-BBn and the benzyl ether of nopol (6,6-dimethyl-bicyclohept-2-ene-2-ethanol).The limiting factor in obtaining high enantiomeric induction is often the enantiomeric purity of the α-pinene.With 100percent enantiomerically pure α-pinene, propargyl alcohols of essentially 100percent ee can be obtained.A predictive rationalization of the transition state leading to this remarkable selection is presented.The acetylene unit of the propargyl alcohol provides a convenient handle for transformations to other useful, optically-active products.The use of propargyl alcohols for the synthesis of optically-active α- and β-substituted γ-lactones, and δ-lactones is illustrated.
- Midland, M. Mark,Tramontano, Alfonso,Kazubski, Aleksander,Graham, Richard S.,Tsai, David J. S.,Cardin, Daniel B.
-
p. 1371 - 1380
(2007/10/02)
-
- Synthetic Applications of the Enantioselective Reduction by Binaphthol-Modified Lithium Aluminum Hydride Reagents
-
The reduction of prochiral carbonyl substrates with the chiral binaphthol-modified lithium aluminum hydride reagents provides an effective means for preparing alcoholic products of high optical purity.The reaction is applicable to a variety of structurally diverse unsaturated carbonyl compounds such as aromatic ketones, acetylenic ketones, olefinic ketones and aldehydes, etc.Either of the antipodes is obtainable in a predictable manner by choosing the handedness of the auxiliary binaphthol ligand.The utility is exemplified by the efficiently stereocontrolled synthesis of prostaglandin intermediates, some insect pheromones, chiral primary terpenic alcohols, optically active styrene oxide, etc.
- Noyori, R.,Tomino, I.,Yamada, M.,Nishizawa, M.
-
p. 6717 - 6725
(2007/10/02)
-
- Reduction of α,β-Acetylenic Ketones to (S)-Propargyl Alcohols of High Enantiomeric Purity
-
(S)-Propargyl alcohols may be obtained in 86-96percent enantiomeric purity by asymmetric reduction of α,β-acetylenic ketones with the 9-borabicyclononane (9-BBN) adduct of nopol benzyl ether.
- Midland, Mark M.,Kazubski, Aleksander
-
p. 2814 - 2816
(2007/10/02)
-
- Enzymic Resolution of (+/-)-Acyclic Alcohols via Asymmetric Hydrolysis of Corresponding Acetates by Microorganisms
-
Asymmetric hydrolysis of (+/-)-1-pentyl-2-propynyl and 1-pentyl-2-propenyl acetates by selected microorganisms produced chiral 1-octyn-3-ol and 1-octen-3-ol, respectively, with high optical purities and acetates of their antipodes.Enantioselectivity of microbial hydrolysis changed with the microorganisms used.Also, (+/-)-1-ethylhexyl acetate was asymmetrically hydrolyzed by microorganisms to give (S)-3-octanol and (R)-1-ethylhexyl acetate of relatively low optical purity and hydrolytic ratio, compared with those of (+/-)-1-pentyl-2-propynyl acetate.
- Oritani, Takayuki,Yamashita, Kyohei
-
p. 2407 - 2412
(2007/10/02)
-