Enantioselective Reductive Coupling of 1,3-Enynes to Glyoxalates Mediated by Hydrogen:  Asymmetric Synthesis of β,γ-Unsaturated α-Hydroxy Esters

• Published in: Organic letters Vol. 9; no. 19; pp. 3745 - 3748
• Main Authors: Hong, Young-Taek, Cho, Chang-Woo, Skucas, Eduardas, Krische, Michael J
• Format: Journal Article
• Language: English
• Published: WASHINGTON American Chemical Society 13.09.2007; Amer Chemical Soc
• Subjects: Catalysis; Chemistry; Chemistry, Organic; Esters - chemical synthesis; Esters - chemistry; Ethylenes - chemistry; Hydrogen - chemistry; Molecular Structure; Oxalates - chemistry; Physical Sciences; Science & Technology; Stereoisomerism; AMINO-ACID; ALKENYLZINC ADDITIONS; BOND-FORMING HYDROGENATION; ALLYLIC ALCOHOLS; VINYL KETONES; RHODIUM-CATALYZED HYDROGENATION; CONJUGATED ALKYNES; AROMATIC-ALDEHYDES; KETO ALDEHYDES; CYCLIZATION
• ISSN: 1523-7060; 1523-7052
• DOI: 10.1021/ol7015548

Catalytic hydrogenation of 1,3-enynes 1a−8a in the presence of ethyl glyoxalate at ambient pressure and temperature using a rhodium catalyst modified by (R)-(3,5- t Bu-4-MeOPh)-MeO-BIPHEP results in highly regio- and enantioselective reductive coupling to furnish the corresponding α-hydroxy esters 1b−8b. As demonstrated by the elaboration of α-hydroxy ester 1b, the terminal and internal olefin moieties embodied by the diene side chain are subject to selective manipulation, one over the other.