Ring closing metathesis in organic synthesis: Evolution of a high speed, solid phase method for the preparation of beta-turn mimetics.

Complimentary solid phase syntheses of the Freidinger lactam class of p-tur n mimetics have been developed using ring closing metathesis as both the ke y carbon-carbon bond forming step and the cyclative cleavage mechanism. Sol id phase variants of the Fukuyama-Mitsunobu process were utilized as pad of a rapid three-step sequence to construct immobilized lactam precursors, an alternative solid phase process is offered which utilizes an Ugi/ring clos ing metathesis reaction tandem to deliver the desired compounds in two synt hetic operations. (C) 1999 Published by Elsevier Science Ltd, All rights re served.