Cleavage of a Chiral Auxiliary Using RCM on an Especially Sterically Crowded Alkene: Syntheses of Chiral Carbo- and Heterocycles.

Abstract Chiral 1,5-, 1,6-, and 1,7-dienes generated in 3–4 steps from chiral auxiliary p -menthane-3-carboxaldehyde undergo RCM with notable discrepancies in reactivity depending on the nature and number of substituents flanking the central double bond. The chiral auxiliary is thus cleaved releasing a carbo- or heterocycle in the process. Special features concerning the RCM on these especially crowded systems are discussed.