Alkynyliodonium salts in organic synthesis. Application to the total synthesis of (-)-agelastatin A and (-)-agelastatin B.

The asymmetric total syntheses of (-)-agelastatin A and (-)-agelastatin B were accomplished in 14 steps each from (R)-epichlorohydrin. The pivotal transformation in both sequences was a sulfinate-promoted cyclization of an alkynyliodonium salt to furnish a key functionalized cyclopentene intermediate. Selective bromination in the final step led to either agelastatin A or agelastatin B, depending upon conditions.