214287-10-2Relevant academic research and scientific papers
A Catalyst Designed for the Enantioselective Construction of Methyl- and Alkyl-Substituted Tertiary Stereocenters
Claraz, Aurlie,Sahoo, Gokarneswar,Berta, Dnes,Madarsz, dm,Ppai, Imre,Pihko, Petri M.
supporting information, p. 669 - 673 (2016/02/27)
Tertiary methyl-substituted stereocenters are present in numerous biologically active natural products. Reported herein is a catalytic enantioselective method for accessing these chiral building blocks using the Mukaiyama-Michael reaction between silyl ketene thioacetals and acrolein. To enable remote enantioface control on the nucleophile, a new iminium catalyst, optimized by three-parameter tuning and by identifying substituent effects on enantioselectivity, was designed. The catalytic process allows rapid access to chiral thioesters, amides, aldehydes, and ketones bearing an α-methyl stereocenter with excellent enantioselectivities, and allowed rapid access to the C4-C13 segment of (-)-bistramide A. DFT calculations rationalized the observed sense and level of enantioselectivity.
The triisopropylsilyl effect: Exceptional Cram-type selectivity in Mukaiyama aldol reactions of a silyl ketene thioacetal
Davis, Anthony P.,Plunkett, Stephen J.,Muir, Jayne E.
, p. 1797 - 1798 (2007/10/03)
The level of 1,2-asymmetric induction in the BF3·OEt2-promoted addition of silyl ketene thioacetals to α-asymmetric aldehydes is affected by the bulk of the silyl group; unprecedented Cram-type selectivity is given by the triisopropylsilyl derivative 8a.
