Tin for Organic Synthesis, 11. A Mild and Effective Synthesis of α,β‐unsaturated Carboxamides and Sulfonamides by Electrophilic Substitution of Alkenylstannanes with Isocyanates

Abstract

AbstractA new and effective method for the preparation of a variety of olefinic carboxamides 6a–k and N‐(4‐methylphenyl‐sulfonyl) carboxamides 7a–d is described. The reaction of aryl and alkyl isocyanates 4a–c or 4‐methylphenylsulfonyl isocyanate 5 with 1‐alkenyltrialkylstannanes 1a–e and di‐1‐alkenyldibutylstannanes 2a–c in the presence of aluminium trichloride provides the corresponding N‐aryl‐substituted olefinic carboxamides 6a–k or the N‐(4‐methylphenyl‐sulfonyl)‐substituted olefinic carboxamides 7a–d in good yields. The stannyl moiety is superior to hydrogen as a leaving group and enables electrophilic ipso substitution at the vinylic system. In the case of di‐1‐alkenyldibutylstannanes the substitutions are also stereospecific, whereas the reactions of 1‐alkenyltrialkylstannanes with isocyanates proceed with partial isomerisation.