Total synthesis of (-)-aplaminal.

The total synthesis and assignment of absolute configuration of (-)-aplaminal ( 1), a cytotoxic metabolite from a sea hare possessing a triazobicyclo[3.2.1]octane skeleton, has been achieved. The synthesis entailed condensation of a monoprotected diamine ( 3) with dimethyl 2-oxomalonate ( 4) to generate the imidazolidine core ( 2). Introduction of the third nitrogen via Mitsunobu activation and azide displacement, followed by reduction and lactam formation (AlMe 3), furnished (-)-aplaminal ( 1). Overall, the synthesis entailed 9 steps and proceeded in 19% overall yield.