Amino acid mediated intramolecular asymmetric aldol reaction to construct a new chiral bicyclic enedione containing a seven-membered ring: remarkable inversion of enantioselectivity compared to the six-membered ring example.

A detailed study to assess the enantioselectivity of the amino acid mediated intramolecular asymmetric aldol reaction of 1,3-cycloheptanedione bearing a C-2 methyl substituent has been undertaken. The cyclizations were mediated by a series of l-amino acids in the presence of an acid cocatalyst. Strikingly, the process is characterized by an inversion of enantioselectivity when compared to a similar reaction involving the 1,3-cyclohexanedione counterpart.