A simple and convenient synthesis of β-amino alcohol chiral auxiliaries based on limonene oxide
作者:Will Chrisman、Jason N Camara、Kim Marcellini、Bakthan Singaram、Christian T Goralski、Dennis L Hasha、Philip R Rudolf、Lawrence W Nicholson、Karen K Borodychuk
DOI:10.1016/s0040-4039(01)01135-2
日期:2001.8
A series of chiralβ-aminoalcohols was prepared by the reaction of secondary amines with a 1:1 mixture of cis- and trans-limonene oxide in the presence of water as a catalyst. The β-aminoalcohol obtained was derived from the trans-limonene oxide, and the unreacted cis-limonene oxide was recovered from the reaction mixture. The β-aminoalcohols are useful chiralauxiliaries for the addition of diethylzinc
Asymmetric addition of diethylzinc to aldehydes catalyzed by β-amino alcohols derived from limonene oxide
作者:Derek Steiner、Steven G. Sethofer、Christian T. Goralski、Bakthan Singaram
DOI:10.1016/s0957-4166(02)00342-7
日期:2002.8
A series of β-amino alcohols, conveniently prepared from limonene oxide, were evaluated as catalysts for the enantioselectiveaddition of dialkylzinc to benzaldehyde. These limonene-based amino alcohols are of particular interest because they are easily synthesized in both enantiomeric forms. Ethylation of benzaldehyde using diethylzinc and catalyzed by limonene derived amino alcohols proceeded with
Scale-Up of the Preparation of (1<i>R</i>,2<i>R</i>,4<i>S</i>)-1-Methyl-4-(1-methylethenyl)-2-(4-morpholinyl)cyclohexanol
作者:Christian T. Goralski、Dennis L. Hasha、Bakthan Singaram、Derek Steiner
DOI:10.1021/op700092n
日期:2007.7.1
Chiral beta-amino alcohols are widely recognized as effective chiral auxiliaries for a variety of asymmetric organic transformations. Recently, (1R,2R,4S)-1-methyl-4-(1-methylethenyl)-2-(4-morpholinyl)cyclohexanol has been reported to be an effective chiral auxiliary for the asymmetric addition of diethylzinc to benzaldehyde and the asymmetric addition of lithium cyclopropylacetylide to 4-(trifluoromethyl)-2(1H)-quinazolinones. This paper describes the scale-up of the reaction of morpholine with cis/trans-(S)-(-)-limonene oxide (99% ee) in the presence of water to produce 125 g of (1R,2R,4S)-1-methyl-4-(1-methylethenyl)2-(4-morpholinyl)cyclohexanol of 99.6% diastereomeric purity.