Total synthesis of (+/-)-goniomitine via a formal nitrile/donor-acceptor cyclopropane [3 + 2] cyclization.

The total synthesis of (+/-)-goniomitine has been accomplished in 17 linear steps with 5.2% overall yield starting from commercially available delta-valerolactam. A synthetic highlight includes the first application of a formal [3 + 2] cycloaddition between a highly functionalized nitrile and a donor-acceptor cyclopropane to prepare an indole nucleus. The use of a microwave reactor is shown to greatly improve the reaction times for two steps.