Lipase-mediated resolution of 2-cyclohexen-1-ols as chiral buildingblocks en route to eburnane alkaloids
摘要:
Lipase catalyzed esterification of several 2-cyclohexen-1-ols proceeds with excellent enantioselectivity leading to (S)-enantiomers as promising chiral building blocks en route to eburnane alkaloids
α-phenylthio β,γ-unsaturated carbonyl compound through an α,β-epoxy sulfoxide. Oxidation of the sulfide with 2.1 equivalents of m-chloroperbenzoic acid gave α,β-unsaturated γ-phenylsulfinyloxy carbonyl compound via sulfoxide-sulfenate rearrangement. The sulfinate was easily hydrolyzed with aqueous potassium hydroxide to afford α,β-unsaturatedγ-hydroxy carbonyl compound in good yield. When optically active
readily react with ethereal H2O2 in the presence of catalytic amounts of Na2MoO4-gly or MoO2(acac)2, affording the C═C trans hydroxylation–hydroperoxylation products in good yields with high regio- and stereoselectivity. Use of enantiomers of cyclic substrates resulted in corresponding enantiopure diol-tert-hydroperoxides. The possibility of further conversion of the diol-tert-hydroperoxides into triols
在催化量的Na 2 MoO 4 -gly或MoO 2(acac)2的存在下,一系列烯丙醇易于与醚H 2 O 2反应,从而以高收率提供C═C反羟基化-氢过氧化产物具有高区域选择性和立体选择性。使用环状底物的对映异构体产生相应的对映体纯的二醇-叔氢过氧化物。还举例说明了将二醇-叔氢过氧化物进一步转化为具有包含季中心的分离的叔-过氧基团的三醇或线性结构单元的可能性。
Chemo-enzymatic preparation of optically active endo-bicyclo[4.1.0]heptan-2-ols
Resolutions of endo-bicyclo[4.1.0]heptan-2-ols were achieved by acylation in the presence of lipase from Candida antarctica (Novozym(R)). The (1S,2R,6R) enantiomers reacted faster and the enantiomeric ratios were between 60 and 800 for the 6-substituted bicycloalkanols. (C) 1999 Published by Elsevier Science Ltd. All rights reserved.