A Diversity-Oriented Approach to Spirocyclic and Fused Hydantoins via Olefin Metathesis

摘要

An efficient and general method is reported to prepare a diversenseries of 5,5-spirocyclic and 1,5-, 4,5-, and 3,4-fused bicyclic imidazolidinonenderivatives based on selective alkylation and ring closing metathesis (RCM) bynexploiting the four possible points of diversity in the hydantoin ring. Hydantoinsncontaining trienes and tetraenes undergo selective RCM and cross metathesis tonafford functionalized spirohydantoins. A tandem metathesis sequence involvingnring closing−ring opening−ring closing and cross metathesis (RC−RO−RC−CM)noccurred with a hydantoin triene to give a bicyclic hydantoin dimer in high yield.nThe fused bicylic dimer could participate in cross metathesis to produce anfunctionalized fused hydantoin derivative. The methodology establishes novelnroutes to unnatural amino acids, proline homologues, and cyclic vicinal diamines.