Diastereoselectivities Realized in the Amino Acid Catalyzed Aldol Cyclizations of Triketo Acetonides of Differing Ring Size

A study designed to assess the diastereoselectivity of the intramolecular aldol reaction of two differently sized monocyclic 1,3-diketones bearing a chiral, oxygenated side chain has been undertaken. The cyclizations were brought about under catalysis by pyrrolidine, a series of d- and l-amino acids including proline, and several proline derivatives. The levels of selectivity were found to be consistently higher with the six-membered ring system than its cycloheptane counterpart.