The enantioselective and diastereoselective hydrogenation of N-heteroaromatic compounds is an efficient strategy to access chirally enriched cyclic heterocycles, which often possess highly bio-active properties. This strategy, however, has only been...

Formal stereocontrolled syntheses of (±)- and (+)-C9-deoxyomuralide is reported, constituting one of the shortest routes to the full carbon skeleton reported to date.

We report herein the first examples of asymmetric oxidation of enol ether and ester substrates using iminium salt organocatalysis, affording moderate to excellent enantioselectivities of up to 98% ee for tetralone-derived substrates in the -hydroxyketone products. A comprehensive density functional theory study was undertaken to interpret the competing diastereoisomeric transition states in this example in order to identify the origins of enantioselectivity. The calculations, performed at the B3LYP/6-31G(D) level of theory, gave good agreement with the experimental results, in terms of the magnitude of the effects under the specified reaction conditions, and in terms of the preferential formation of the (R)-enantiomer. Just one of the 30 characterized transition states dominates the enantioselectivity, which is attributed to the adoption of an orientation relative to stereochemical features of the chiral controlling element that combines a CH- interaction between a CH 2 group in the substrate and one of the aromatic rings of the biaryl section of the chiral auxiliary with a good alignment of the acetoxy group with the other biaryl ring, and places the smallest substituent on the alkene (a hydrogen atom) in the most sterically-hindered position. Introduction The α-hydroxycarbonyl motif is present in many natural products and in intermediates towards their syntheses. 1 A simple method to prepare α-hydroxycarbonyls involves the oxidation of silyl enol ethers, and is known as the Rubottom reaction. Rubottom, 2 Brook, 3 and Hassner 4 first reported the use of m-chloroperbenzoic acid to oxidize silyl enol ethers to form α-hydroxy-ketones and aldehydes

A formal, stereocontrolled synthesis of lactacystin has been completed from t-Bu-O-l-serine.