Chiral aminoalcohols with a menthane skeleton as catalysts for the enantioselective addition of diethylzinc to benzaldehyde
摘要:
Novel chiral aminoalcohols were synthesized by highly diastereoselective addition of Me3SiCN and LICH2CN to (-)-menthone followed by LiAlH4 reduction. The addition of CH2=CH-MgBr and PhCH=CH-MgBr to menthone and the following epoxidation, provided useful hydroxy epoxides, one of which could be aminolyzed to afford an aminodiol. In one case, the configuration of the newly formed epoxidic stereogenic center was determined by X-ray crystallography. When applied as catalysts in the enantioselective addition of Et2Zn to benzaldehyde, the aminoalcohols induced enantiomeric excesses (e.e.s) of up to 77%. (C) 2001 Elsevier Science Ltd. All rights reserved.
First example of axial selectivity in the nucleophilic addition to (−)-menthone—addition of cyanomethyl lithium †Dedicated to Professor Dr. Manfred Hesse on the occasion of his 65th birthday. †
作者:Vladimir Dimitrov、Stefan Panev
DOI:10.1016/s0957-4166(00)00099-9
日期:2000.4
The addition of cyanomethyl lithium to (−)-menthone at −78°C followed by 1.5 h stirring at room temperature and acidic workup produced exclusively the axialaddition product, being the first example of preferred axial attack of an organometallic reagent to menthone. In the case of hydrolysis at −78°C after 0.5 h reaction time the equatorial addition product was isolated as the preferably formed isomer