One-flask tethered ring closing metathesis-electrocyclic ring opening for the highly stereoselective synthesis of conjugated Z/E-dienes

摘要

A one-flask reaction sequence comprising ring closing metathesis (RCM) of butenoates derived from allylic alcohols and a base-mediated ring opening gives 2Z,4E-configured dienoic acids in high yields and stereoselectivities. Application of the method to the synthesis of the natural product fusanolide A suggests that the originally published structure was erroneously assigned and should be revised. Ring closing metathesis (RCM) of butenoates derived from allylic alcohols can be combined with base-induced ring opening in a one-flask sequence. In this way, dienoic acids become accessible in an operationally simple procedure in very high yields and excellent stereoselectivities, with the tether remaining in the product as a valuable functional group for further transformations.