Efficient construction of stereodefined alpha-alkylidene aza-cycloketones via beta-amino-alkenyllithium: straightforward and protection-free synthesis of allopumiliotoxin 267A.

Intramolecular nucleophilic acyl substitution of highly functionalized beta-amino-alkenyllithium species provided facile access to alpha-alkylidene aza-cycloketones with defined olefin geometry and rich structural diversity. A concise total synthesis of allopumiliotoxin 267A has been accomplished in 5 steps from 4 featuring this key transformation.