Oxidative cleavage of mono-, di-, and trisubstituted olefins to methyl esters through ozonolysis in methanolic sodium hydroxide
摘要:
The ozonolysis of alkenes in methanolic NaOH or NaOMe with CH2Cl2 as cosolvent leads directly to methyl esters. The procedure has been used to prepare various alpha-, beta, and omega-alkoxy esters, acyloxy esters, and alpha- and beta-N-acyl and N-sulfonyl esters from the appropriate unsaturated ethers, esters, and amides. Other examples include the formation of dimethyl octanedioate from cyclooctene (75% yield), dimethyl nonanedioate and methyl nonanoate from methyl oleate (77 and 78%, respectively), and tetradecanoic acid gamma-lactone from 2-methyl-2-hexadecen-6-ol (80% yield).
Synthesis of optically active alkynyl alcohols and α-hydroxy esters by microbial asymmetric hydrolysis of the corresponding acetates
作者:Kenji Mori、Hiroko Akao
DOI:10.1016/0040-4020(80)85030-7
日期:1980.1
Asymmetric hydrolysis of the acetates of racemic alkynyl alcohols and α-hydroxy esters by Bacillus subtilis var. Niger afforded optically active acetates and alcohols in 7–90% optical purities. The both enantiomers of optically pure mandelie acid were prepared by this microbial method.
New synthesis of a chiral steroid cd-ring synthon by means of enantioselective double Michael addition
作者:Takashi Takahashi、Hiroshi Okumoto、Jiro Tsuji
DOI:10.1016/s0040-4039(01)90077-2
日期:1984.1
A new synthetic method of (+)-(1R)-acetyl-(7aR)-methyl-4-hydroinden-5-one (2) by highly enantioselective double Michael addition involving alkenylcopper-phosphine complex, 3-trimethylsilylbutenone and 2-methyl-2-cyclo-pentenone is presented.
HIGHLY ENANTIOSPECIFIC AND ERYTHRO-SELECTIVE [2,3]-WITTIG REARRANGEMENT OF ENANTIOMERICALLY-ENRICHED ALLYLIC BENZYL ETHERS. A NEW, FORMAL CHIRAL SYNTHESIS OF<i>l</i>-EPHEDRINE
作者:Noboru Sayo、Ei-ichiro Kitahara、Takeshi Nakai
DOI:10.1246/cl.1984.259
日期:1984.2.5
The [2,3]-Wittigrearrangement of chiral (Z)-allylic benzyl ethers provides 94–97% of asymmetric transfer (enantiospecificity), along with 90–96% of erythroselectivity. Its synthetic potential is illustrated through the stereocontrolled synthesis of an optically-active precursor of l-ephedrine.
Asymmetric synthesis of optically active compounds
申请人:Hoffmann-La Roche Inc.
公开号:US04000169A1
公开(公告)日:1976-12-28
Asymmetric synthesis of optically active 3,7,11-trimethyl-dodecan-1-ol, an intermediate for producing optically active vitamin E, from isovaleraldehyde or prenal including intermediates in this synthesis.
Reductive cleavages of homochiral acetalsusing Lewis acid-hydride systems and of alkynyl acetalsusingorganoaluminumreagents are described. Stereochemical outcomes are found to be the opposite compared with our previous results on the aluminum hydride reduction of the acetal.