Synthesis of .gamma.- and .delta.-lactones by free-radical annelation of Se-phenyl selenocarbonates
作者:Mario D. Bachi、Eric Bosch
DOI:10.1021/jo00043a030
日期:1992.8
A general method for the synthesis of gamma- and delta-lactones through the intramolecular addition of alkoxycarbonyl radicals, formed by reaction of Se-phenylselenocarbonates with n-Bu3SnH, onto carbon-carbon multiple bonds is described. This free-radical cyclization is characterized by high regioselectivity favoring exo addition and by a high ratio of cyclization to reduction. Monocyclic, fused bicyclic, and spirocyclic lactones are formed in good to excellent yield. Use of allyltri-n-butyltin as a chain-transfer agent in the place of n-Bu3SnH affords the corresponding 3-butenyl lactones.
Synthesis of lactones by intramolecular addition of alkoxythiocarbonyl free radicals to acetylenes
作者:Kyoko Nozaki、Koichiro Oshima、Kiitiro Utimoto
DOI:10.1016/s0040-4039(00)82284-4
日期:——
Conformational effects on lipase-mediated acylations of 2-substituted cyclohexanols
作者:Rikuhei Tanikaga、Yoshimasa Matsumoto、Maki Sakaguchi、Yohei Koyama、Kentaro Ono
DOI:10.1016/s0040-4039(03)01514-4
日期:2003.8
Lipase-mediated acetylations of trans- and cis-2-substituted cyclohexanols gave the corresponding (1R)-cyclohexyl acetates and (IS)-cyclohexanols in high yields and ee, but c-4-tert-butyl-c-2-ethenyl-r-l-cyclohexanoI was unreactive owing to the steric interaction between the axial OH group and the axial H atoms at the 3- and 5-positions. In the cis-isomer the OH group occupies an equatorial position to bind to the lipase, and less bulky axial alkenyl and alkynyl groups might not so much prevent acetylations than an alkyl group. (C) 2003 Elsevier Ltd. All rights reserved.
Facile Reduction of Dithiocarbonates Derived from Secondary Alcohols with<i>n</i>-Bu<sub>3</sub>SnH–Et<sub>3</sub>B and Synthesis of 2-Furanthiones and 2-Furanones by Intramolecular Addition of Alkoxythiocarbonyl Free Radicals to Acetylenic Linkages
作者:Kyoko Nozaki、Koichiro Oshima、Kiitiro Utimoto
DOI:10.1246/bcsj.63.2578
日期:1990.9
reduction of dithiocarbonates or thiocarbonates by n-Bu3SnH–Et3B easily gives the corresponding hydrocarbons. The intermediate alkoxythiocarbonyl radical equivalents are trapped by properly located carbon–carbon multiple bonds. The dithiocarbonates derived from either homopropargylic or homoallylic alcohols produce tetrahydrofuranones upon treatment with n-Bu3SnH–Et3B. Application of this new method