Asymmetric Hydrogenation of Unfunctionalized, Purely Alkyl-Substituted Olefins

Abstract

Asymmetric hydrogenation of olefins is one of the most useful reactions for the synthesis of optically active compounds, especially in industry. However, the application range of the catalysts developed so far is limited to alkenes with a coordinating functional group or an aryl substituent next to the double bond. We have found a class of chiral iridium catalysts that give high enantioselectivity in the hydrogenation of unfunctionalized, trialkyl-substituted olefins. Because these catalysts do not require the presence of any particular functional group or aryl substituent in the substrate, they considerably broaden the scope of asymmetric hydrogenation.

Chiral pyridyl phosphinites with large aryl substituents as efficient ligands for the asymmetric iridium-catalyzed hydrogenation of difficult substrates

“…We were c From our previous report ref. 20. pleased to see excellent enantioselectivity of greater than 99% ee and an increase in diastereoselectivity with catalyst 7c compared to the best results of our previous study with catalysts 8 and 6a.…”

Hydrogenation in the Vitamins and Fine Chemicals Industry – An Overview

“…By applying this novel retrosynthetic concept, an (all-R)-tocopherol derivative could be obtained for the first time from the corresponding (all-E)-tocotrienol derivative in a collaboration of the Pfaltz group with DSM Nutritional Products. Asymmetric hydrogenation of γ-tocotrienyl acetate (R,E,E)-59 with pyridyl phosphinite 60 yielded acetate 61 with complete conversion and excellent stereoselectivity (>98% R,R,R) [63,64]. A Rh(I)-catalysed highly diastereoselective hydrogenation is the basis for a very short synthesis of (+)-biotin (26) developed by Lonza and applied on a technical scale (Scheme 19).…”

Multi-Bond Forming Processes in Efficient Synthesis

“…Sharpless and coworkers' six-fold dihydroxylation of squalene from 1993 is a landmark example of the enantiopurity amplification that results from a reagentcontrolled, multi-bond forming reaction. [177][178][179] The breathtakingly short approaches to polyether natural products (þ)-omaezakianol (Scheme 5) [64] and glabrescol [180] by Corey and coworkers feature stereoselective five-and four-fold epoxidations, respectively. Paterson et al's synthesis of the DEF tricyclic spiroketal fragment of spirastrellolide A (Scheme 29) [181] is another example of ingenious synthetic design using independent reactions combined with domino sequences.…”