Indirect N-vinylation of indoles via isomerisation of N-allyl derivatives: synthesis of (±)-debromoarborescidine B

Double bond migration in N-allylindoles has been investigated as a method to access N-vinyl derivatives of this heterocycle. The optimal reaction conditions employed t-BuOK or NaH in DMSO as the solvent at room temperature to afford the products in yields ranging from 51 to 99%. Although in some cases a high degree of stereoselectivity was observed, preferential formation of either the Z- or E-isomer was not predictable. The developed methodology was employed in the synthesis of (±)-debromoarborescidine B.