Xiang-Ping Hu and Zhuo Zheng of the Dalian Institute of Chemical Physics developed (Organic Lett. 2009, 11, 3226; J. Org. Chem. 2009, 74, 9191) a family of Rh catalysts for the enantioselective hydrogenation of allylic phosphonates such as 1. Hon Wai Lam of the University of Edinburgh established (J. Am. Chem. Soc. 2009, 131, 10386) that an alkenyl heterocycle 3 could be reduced with high ee. The product 4 could be hydrolyzed to the carboxylic acid. Ken Tanaka of the Tokyo University of Agriculture and Technology showed (J. Am. Chem. Soc. 2009, 131, 12552) that an isopropenyl amide 6 could be hydroacylated with high ee. Gregory C. Fu of MIT observed (J. Am. Chem. Soc. 2009, 131, 14231) that nitromethane 9 could be added to the allenyl amide 8 to give 10, the product of γ-bond formation. Robert K. Boeckman Jr. of the University of Rochester devised (Organic Lett. 2009, 11, 4544) what appears to be a general protocol for the construction of alkylated ternary and quaternary centers: enantioselective hydroxymethylation of an aldehyde 11. In another approach to the construction of alkylated quaternary centers, Varinder K. Aggarwal of the University of Bristol demonstrated (Angew. Chem. Int. Ed. 2009, 48, 6289) that an enantiomerically enriched trifluoroborate salt 14 could be added to an aromatic aldehyde 15 with retention of absolute configuration. The salt 14 was prepared from the corresponding high ee secondary benzyl alcohol. Weinreb amides are versatile precursors to a variety of functional groups. Stephen G. Davies of the University of Oxford devised (Organic Lett. 2009, 11, 3254) a chiral Weinreb amide equivalent 17 that could be alkylated with high de. The minor diastereomer from the alkylation was readily separable by silica gel chromatography. Keiji Maruoka of Kyoto University established (Angew. Chem. Int. Ed. 2009, 48, 5014) that a chiral phase transfer catalyst was effective for the enantioselective alkylation of the alkynyl ester 19. Emmanuel Riguet of the Université de Reims Champagne-Ardenne developed (Tetrahedron Lett. 2009, 50, 4283) an improved catalyst for the enantioselective addition of malonate 22 to cyclohexenone 21.
Frobenius n-homomorphisms, transfers and branched coverings
