Isomerization of Olefins by Means of R3SnH-Et3B and Stereochemical Study on Reduction of Alkenyl Iodides

Article abstract of DOI:10.1246/bcsj.65.349

Isomerization of olefins with R3SnH-Et3B (R = Ph or n-Bu) system has been studied.Treatment of (Z)-1-triphenylstannyl-1-octene (1) or (E)-1-triphenylstannyl-1-octene (2) with a catalytic amount of Ph3SnH-Et3B provided an equilibrium mixture of 1/2 = 2/8.Partial isomerization was observed in the reaction of trivial alkenes such as 6-dodecene and 2,2-dimethyl-3-dodecene with R3SnH-Et3B system.Whereas (Z)- or (E)-6-dodecene was recovered unchanged upon treatment with n-Bu3SnH-Et3B at -78 deg C for 3 h, stirring a benzene solution of (Z)-6-dodecene, Ph3SnH, and Et3B at 60 deg C for 5 h gave an isomeric mixture of ()-6-dodecene and (E)-6-dodecene (Z/E = 64/36).Taking account of these results, the stereochemistry of the reduction of alkenyl iodides at -78 deg C with R3SnH-Et3B system was studied. 6-Dodecenyl radical proved to isomerize much more rapidly than it abstracts a hydrogen from R3SnH.