Diels-Alder reactions of 2-Alkenylboranes and cis-1-alkenylboranes. Anomalous selectivity that allows a choice of regiochemistry
作者:Daniel A. Singleton、Kyeongsook Kim、Jose P. Martinez
DOI:10.1016/s0040-4039(00)93382-3
日期:1993.5
2-Alkenyl- and cis-1-alkenylboranes are highly reactive Diels-Alder dienophiles which display unusual selectivity patters. By taking advantage of a reversal of regiochemistry of reaction with alkenyldihalo- versus alkenyldialkylboranes, any desired regioisomeric product may be favored, usually with very high selectivity.
The Reduction of Stereoisomeric 6-<i>tert</i>-Butyl-3-methoxy-3-methylcyclohexenes with Lithium in Ethylamine
作者:Tadashi Masamune、Hajime Matsue、Matsuo Fujii
DOI:10.1246/bcsj.45.1812
日期:1972.6
The synthesis and reduction with lithium in ethylamine of the entitled stereoisomeric allyl ethers 1 and 2 are described. The reaction of both the isomers occurred very readily with concomitant cleavage of the methoxy groups, and gave the same products, 4-tert-butyl-1 -methylcyclohexene (13), and c- and t-3-tert-butyl-6-methylcyclohex-1-enes (14 and 15), in the same ratio (87 : 4 : 9), indicating that the respective reactions involved a common intermediate (16). Moreover, the reduction of the cis-isomer 1 with an axial methoxy group proceeded much more rapidly than that of the trans-isomer 2 with an equatorial methoxy.