89402-46-0Relevant academic research and scientific papers
Regio-, Diastereo-, and Enantioselective Synthesis of vic-Diols via α-Silyl Ketones According to the SAMP/RAMP Hydrazone Method
Enders, Dieter,Nakai, Shiro
, p. 219 - 226 (2007/10/02)
α-Silylated ketones 5 or 10 of high enantiomeric purity (ee>=90percent) are easily available by silylation or silylation/alkylation of ketones 1 or 6, resp., according to the SAMP/RAMP hydrazone method.Reduction of 5 or 10 with L-selectride, followed by oxidative cleavage of the C-Si bond, leads to vic-diols 11-13 with high diastereoselectivity (de>=90percent) and without racemization.The stereoselectivity of the reduction depends on the structure of the α-silyl ketones 5 or 10, the reducing reagents, and the solvents used.Key Words: Ketones, α-silyl / vic-Diols, diastereo- and enantioselective synthesis / SAMP/RAMP Hydrazones / L-Selectride reductions
ASYMMETRIC SYNTHESIS OF β-SUBSTITUTED δ-KETOESTERS VIA MICHAEL-ADDITIONS OF SAMP/RAMP-HYDRAZONES TO α,β-UNSATURATED ESTERS, VIRTUALLY COMPLETE 1.6-ASYMMETRIC INDUCTION
Enders, Dieter,Papadopoulos, Kyriakos
, p. 4967 - 4970 (2007/10/02)
A simple and efficient 3-step asymmetric synthesis of β-substituted δ-ketoesters 3 in 45-62percent overall chemical yield and >=96-ca.100percent ee is described.The key step is an asymmetric Michael-addition of lithiated methylketone-SAMP- or RAMP-hydrazones to α,β-unsaturated esters 2 with virtually complete 1.6-asymmetric induction.
