Synthesis of optically active forms of (Z)-14-methylhexadec-8-enal
作者:K. Mori、T. Suguro、M. Uchida
DOI:10.1016/0040-4020(78)87008-2
日期:1978.1
The both enantiomers of (Z)-14-methylhexadec-8-enal were synthesized starting from (R)-(+)-citronellol. The (R)-(−)enantiomer (1) was about 250 times more active than its antipode (1') when tested on dermestid beetle.
Selective Epoxidation of Olefins by Perfluoro-<i>cis</i>-2,3-dialkyloxaziridines<sup>1</sup>
作者:Alberto Arnone、Darryl D. DesMarteau、Barbara Novo、Viacheslav A. Petrov、Massimo Pregnolato、Giuseppe Resnati
DOI:10.1021/jo961196h
日期:1996.1.1
Alkyl-substituted olefins are epoxidized by perfluoro-cis-2,3-dialkyloxaziridines under particularly mild conditions. Electron deficient substrates (e.g, alpha,beta-enones) can also be epoxidized, and the more electron poor the double bond is, the more severe the reactions conditions become. The epoxidation is chemoselective (secondary alcohols and their ethers do not interfere), site selective (the monoepoxide of a diene can be obtained), and stereoselective (cis-alkenes afford cis-epoxides). Various complex and polyfunctional substrates of natural origin (monoterpenes, sesquiterpenes, steroids) have been transformed effectively.
Oxyanion Orientation in Anionic Oxy-Cope Rearrangements
作者:Eun Lee、Yong Rok Lee、Bongjin Moon、Ohyun Kwon、Mi Seong Shim、Jae Sook Yun
DOI:10.1021/jo00085a037
日期:1994.3
Efficiency of chirality transfer in anionic oxy-Cope rearrangement depends solely on the orientational preference of the oxyanionic bond in the substrates with a single carbinol carbon chiral center. In chairlike transition-state conformations for the rearrangement of simplest substrates like anions generated from (E)-1-phenyl-1,5-hexadien-3-ol and (E)-1,5-heptadien-4-ol, the oxyanionic bond is more prone to adopt the pseudoaxial orientation. On the other hand, anions generated from (E)-2-methyl-1,5-heptadien-4-ol, (E)-5-tert-butyl-1-phenyl-1,5-hexadien-3-ol, and 4-(2'-methyl-1'-cyclohexenyl)-1-buten-3-ol undergo rearrangement via chairlike transition states in which the pseudoequatorial oxyanionic bond is favored. It can thus be surmized that there is a slight stereoelectronic preference for the pseudoaxial oxyanionic bond in the chairlike transition states for the rearrangement of substrates without steric constraints. Substitution at C5 of the basic 1,5-hexadien-3-ol framework of substrates, however, leads to 1,3-diaxial steric interaction in the chairlike transition states with pseudoaxial oxyanionic bond, and pseudoequatorial disposition of oxyanionic bond becomes more favorable.