A tandem 1,4-reduction-aldol cyclization is induced by exposure of monoenone monoketones to catecholborane in THF at ambient temperature. Six-membered cyclic aldol products are formed in excellent yield with high levels of syn diastereoselectivity for aromatic and heteroaromatic enones. Five-membered ring formation proceeds less readily, but the yield is improved through addition of Rh(I) salts.
R. R. Huddleston, D. F. Cauble, M. J. Krische, J. Org. Chem., 2003, 68, 11-14.
A novel enantioselective synthesis of α-amino acids has been developed, which is broad in scope, simple in application, and advantageous for many α-amino acids of interest in chemistry, biology, medicine.
E. J. Corey, J. O. Link, J. Am. Chem. Soc., 1992, 114, 1906-1908.
Hydroboration with catecholborane, followed by treatment with easily available reagents such as alkenyl sulfones or alkynyl phenyl sulfones in the presence of a radical initiator, represents an effective and simple one-pot procedure for direct vinylation, formylation, and cyanation.
A.-P. Schaffner, V. Darmency, P. Renaud, Angew. Chem. Int. Ed., 2006, 45, 5847-5849.