Benzaldehyde lyase-catalyzed enantioselective carboligation of aromatic aldehydes with mono- and dimethoxy acetaldehyde

[reaction: see text] Benzaldehyde lyase from the Pseudomonas fluorescens catalyzes the reaction of aromatic aldehydes with methoxy and dimethoxy acetaldehyde and furnishes (R)-2-hydroxy-3-methoxy-1-arylpropan-1-one and (R)-2-hydroxy-3,3-dimethoxy-1-arylpropan-1-one in high yields and enantiomeric excess via acyloin linkage. Aromatic aldehydes and benzoins are converted into enamine-carbanion-like intermediates prior to carboligation

A short olefin metathesis-based route to enantiomerically pure arylated dihydropyrans and a,ß-unsaturated delta-Valero lactones

The synthesis of arylated dihydropyrans and unsaturated lactones starting from enantiomerically pure alpha-hydroxy ketones (prepared by an enzyme-catalyzed benzoin condensation) is described. The key steps are a highly diastereoselective addition of vinyl metal compounds under chelate control and a ruthenium-catalyzed ring-closing olefin metathesis reaction. Elucidation of the relative configuration of the final products was achieved by NOE experiments

Development for a donor-acceptor concept for enzymatic cross-coupling reactions of aldehydes : the first asymmetric cross-benzoin condensation

Highly enantioenriched mixed benzoins are obtained selectively through a biocatalytical cross-coupling reaction of aromatic aldehydes using ThDP-dependent enzymes

A Versatile Route to syn- and anti-a-Amino ß-Hydroxy Esters by Dynamic Kinetic Resolution with Ru-SYNPHOS® Catalyst

A general and practical synthesis of both syn- and anti-alpha-amino beta-hydroxy esters with high levels of selectivity by the use of Ru-SYNPHOS(R) catalysts is reported. The key transformations include asymmetric hydrogenations of alpha-N-substituted beta-keto esters protected as alpha-amido or alpha-amino hydrochloride derivatives, respectively. The Ru-II-catalyzed hydrogenation of alpha-amino beta-keto ester hydrochlorides affords the corresponding anti-alpha-amino beta-hydroxy esters with high diastereoselectivities (up to 99%) and enantioselectivities (up to 97%) through dynamic kinetic resolution (DKR). ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)