Pinacol Cross Coupling Reactions of Ethyl 2-Alkyl-2-Formylpropionates. Stereoselective Synthesis of 2,2,4-Trialkyl-3-Hydroxy-γ-Butyrolactones
作者:Min Kang、Jeonghan Park、Steven Pedersen
DOI:10.1055/s-1997-709
日期:——
Intermolecular pinacol coupling of ethyl 2-alkyl-2-formylpropionates (2) (i.e. EtOC(O)CR1MeCHO) with non-chelating aldehydes provides high yields of threo diols. The reaction is promoted by vanadium(II) ions which are conveniently generated in situ from VCl3(THF)3 and zinc dust. high diastereofacial selectivity is observed when starting with chiral 2, or chiral non-chelating aldehydes.
Rh-Catalyzed Asymmetric Hydroformylation of Functionalized 1,1-Disubstituted Olefins
作者:Xiao Wang、Stephen L. Buchwald
DOI:10.1021/ja2092689
日期:2011.11.30
The first method for the highly enantioselective rhodium-catalyzedhydroformylation of 1,1-disubstituted olefins has been developed. By employing either of the P-chirogenic phosphine ligands BenzP* and QuinoxP*, linear aldehydes with β-chirality can be prepared in a highly enantioselective fashion with good chemo- and regioselectivities.
Rhodium-catalyzed asymmetric anti-Markovnikov hydroformylation of α-substituted acrylates/acrylamides has been developed. By employing the Rh/(S,S)-DTBM-YanPhos complex, a series of β-chiral linear aldehydes were obtained in high yields (up to 94% yield) and high enantioselectivities (up to 96% ee). The utility of this methodology is demonstrated by a gram-scale reaction and a concise synthetic route