Acyclic 1,4-Stereocontrol via the Allylic Diazene Rearrangement: Development, Applications, and the Essential Role of Kinetic E Stereoselectivity in Tosylhydrazone Formation

摘要

We report full details of a method for 1,3 reductive transposition of alpha-alkoxy-alpha,beta-unsaturated hydrazones to provide E-alkenes with high 1,4-stereocontrol between the two respective allylic stereocenters. The process couples a chelation-controlled reduction of the hydrazone with an in situ strain controlled retro-ene reaction Of an, allyl diazene, an allylic ,diazene rearrangement. Such stereotriads are frequently observed. motifs in natural products. We observed a fortuitous kinetic preference for the E-hydrazone geometry during the hydrazonation reaction, as only the E-isomers could undergo chelation-controlled reduction.