Domino Doyle‐Kirmse/Claisen‐Thioimidate Rearrangements: Access to 2‐Aminobuta‐1,3‐diene Derivatives of Benzazole‐2‐thiones

A domino sequence consisting of a rhodium‐catalyzed Doyle‐Kirmse rearrangement followed by a Claisen‐thioimidate rearrangement has been developed. This type of thio‐Claisen rearrangement represents the first example reported in the homoallenylsulfenyl series. The sequence involves 2‐propargylsulfenyl benzazoles and diazoesters, affording N‐butadienyl substituted benzazole‐2‐thiones as a mixture of Z and E isomers, in yields ranging from 12% to quantitative (32 examples). The method provides a rapid access to a new family of highly substituted polyfunctionalized 2‐aminobuta‐1,3‐dienes with potential synthetic applications.