Transannular Diels-Alder Reaction Catalyzed by Chiral Oxazaborolidine

Significance

While catalytic, asymmetric intermolecular and intramolecular Diels-Alder reactions are well established, the present paper provides the first report of the corresponding transannular Diels-Alder (TADA) reaction. A survey of various Lewis and Brønsted acid catalysts revealed that oxazaborolidine 1 was the only catalyst able to promote cyclization of macrolactone 2 (n, m = 1). Subsequently, various-sized macrocycles containing α,β-unsaturated lactone or ketone dienophilic moieties were cyclized to furnish tri­cyclic endo products containing medium-to-large-sized rings in good to excellent diastereo- and enantioselectivities.