Spiroborate Ester-Mediated Asymmetric Synthesis of β-Hydroxy Ethers and Its Conversion to Highly Enantiopure β-Amino Ethers
作者:Kun Huang、Margarita Ortiz-Marciales、Wildeliz Correa、Edgardo Pomales、Xaira Y. López
DOI:10.1021/jo900666r
日期:2009.6.5
Borane-mediated reduction of aryl and alkyl ketones with α-aryl- and α-pyridyloxy groups affords β-hydroxy ethers in high enantiomeric purity (up to 99% ee) and in good yield, using as catalyst 10 mol % of spiroborate ester 1 derived from (S)-diphenylprolinol. Representative β-hydroxy ethers are successfully converted to β-amino ethers, with minor epimerization, by phthalimide substitution under Mitsunobu’s
Chiral Epoxides via Borane Reduction of 2-Haloketones Catalyzed by Spiroborate Ester: Application to the Synthesis of Optically Pure 1,2-Hydroxy Ethers and 1,2-Azido Alcohols
作者:Kun Huang、Haiyang Wang、Viatcheslav Stepanenko、Melvin De Jesús、Carilyn Torruellas、Wildeliz Correa、Margarita Ortiz-Marciales
DOI:10.1021/jo102294j
日期:2011.3.18
with 10% spiroaminoborate ester 1 as catalyst is described. By a simple basic workup of 2-halohydrins, optically active epoxides are obtained in high yield and with excellent enantiopurity (up to 99% ee). Ring-opening of oxiranes with phenoxides or sodium azide is investigated under different reaction conditions affording nonracemic 1,2-hydroxy ethers and 1,2-azido alcohols with excellent enantioselectivity