Azobridges from azines, XVII1. Intra- and intermolecular [3+2] cycloaddition between nonstabilized azomethineimines and alkenes
作者:Petra Hoffman、Siegfried Hünig、Leonhard Walz、Karl Peters、Hans-Georg von Schnering
DOI:10.1016/0040-4020(95)00818-s
日期:1995.11
distant position are quatemized by Me3OBF4 to 1,MeBF4 and 3,MeBF4, whereas MeI produces the cage compounds 2,HX and 4,HX. These [3+2] cycloadducts also are quantitatively formed from 1,MeBF4 and 3,MeBF4 with catalytic amounts of azo compounds. Intermolecular [3+2] cycloadditions occur with a mixture of DBH (5) or DBO (8), MeI and a variety of alkenes (→ HI) salts of (6, 7, 9 — 12). The intermediate azomethineimines
Azo bridges from azines. XV. Oxygenation of Unsaturated Cyclic Azo Compounds with peracids
作者:Siegfried H�nig、Michael Schmitt
DOI:10.1002/prac.19963380113
日期:——
Azo bridges in compounds 3, 6, 11, 16, 20 and 22 are chemospecifically oxidized with MCPBA to the corresponding azoxy derivatives 4, 7, 12, 17, 21, and 23 in the presence of one or two (20, 22) double bonds even if these are located in a close parallel position to the azo bridge (6, 11, 20, 22). The order of reactivity of different olefinic moieties towards MCPBA was found to be bicycloheptene > bicyclooctene, cyclopentene. Thus, epoxy/azoxides 5, 8, 13, 14, and 19 as well as bisepoxy/azoxides 10 and 15 were obtained. If both the azo and the olefinic bridge are part of a bicycloheptane system (24) the azo group can be no longer oxidized chemospecifically (25 + 26).