Isothiourea-Catalysed Acylative Kinetic and Dynamic Kinetic Resolution of Planar Chiral Paracyclophanols.

Abstract

The development of synthetic methods for the catalytic enantioselective preparation of planar chiral paracyclophane derivaties is of considerable interest to the synthetic community. To date, relatively few successful and effective organocatalytic approaches to this molecular class have been reported. In this context, this manuscript describes effective isothiourea catalysed acylative kinetic (KR) and dynamic kinetic resolution (DKR) approaches to the generation of a range of planar chiral macrocycles with excellent levels of enantioselectivity. Effective KR of configurationally stable planar chiral macrocyclic phenols with 12- and 13-membered ansa-chains is demonstrated (6 examples, s = up to 50) using 5 mol% of the isothiourea (R)-BTM and isobutyric anhydride. Application to configurationally labile macrocyclic phenols with 14 to 18 membered ansa-chains allows their effective acylative DKR, generating the desired products with excellent enantioselectivity (24 examples, up to 95% yield and 98:2 er).