We have recently found that in the presence of stoichiometric siloxane reductant, copper(I) bis-phosphine complexes catalyze reductive aldol cyclizations of alpha,beta-unsaturated carbonyl compounds tethered to a ketone through either an ester or an amide linkage to form beta-hydroxylactones and beta-hydroxylactams respectively. The reactions proceed with high diastereoselectivities and in moderate to good yields, and in the case of the ester substrates, use of a suitable chiral bis-phosphine allows the products to be isolated with moderate ee (up to 83%). Further studies have uncovered new catalyst systems based upon other metals that increase the efficiency and scope of these reactions. Our recent work in these areas will be presented.