Catalytic Asymmetric Vinylogous Prins Cyclization: A Highly Diastereo and Enantioselective Entry to Tetrahydrofurans.
We describe the design and development of the first catalytic asymmetric vinylogous Prins cyclization. This reaction constitutes an efficient approach for highly diastereo and enantioselective synthesis of tetrahydrofurans (THFs) and is catalyzed by a confined chiral imidodiphosphoric acid (IDP) Aromatic and heteroaromatic aldehydes react with various 3,5 dien 1 ols to afford 2,3 disubstituted THFs in excellent selectivity (d.r. 20:1, e.r. up to 99:1) Aliphatic aldehydes react with similarly excellent results when a highly acidic imidodiphosphorimidate (IDPi) catalyst is used. With a racemic dienyl alcohol, the reaction proceeds via a kinetic resolution. DFT calculations suggest an explanation for unusually high stereoselectivity.
Journal of the American Chemical Society