-Diastereo- and Enantioselective Ruthenium-Catalyzed C-C Coupling-Oxidative Lactonization of 1,4-Butanediol: Alkynes as Allylmetal Pronucleophiles.

Reported methods for enantioselective oxidative lactonization affect desymmetrization of prochiral or -diols, and processes where C-C bond formation accompanies oxidative lactonization are undescribed. Here, using the ruthenium catalyst assembled from RuHCl(CO)(PPh), JOSIPHOS SL-J009-1 and KI, allylative oxidative lactonizations of 1,4-butanediol (10 tons/yr) are described that occur with high levels of -diastereo- and enantioselectivity. As corroborated by deuterium labeling experiments, these processes merge three distinct catalytic events: (a) alkyne-to-allene isomerization, (b) transfer hydrogenative carbonyl (α-aryl)allylation of the allene pronucleophile, and (c) oxidative lactonization of the resulting enantiomerically enriched 1°,2°-diol.