Stereospecific Construction of Chiral Tertiary and Quaternary Carbon by Nucleophilic Cyclopropanation with Bis(iodozincio)methane
作者:Kenichi Nomura、Seijiro Matsubara
DOI:10.1002/asia.200900289
日期:2010.1.4
The reaction of a ketone having a leaving group at the α‐position, such as α,β‐epoxy ketone or α‐sulfonyloxy ketone, with bis(iodozincio)methane affords a zinc alkoxide of cyclopropanol. The reaction proceeds by nucleophilic addition of the dizinc to the carbonyl group and a sequential intramolecular nucleophilic substitution of the introduced iodozinciomethyl group to the adjacent electrophilic carbon
Stereoselective reduction of α,β-epoxy ketones with sodium borohydride in the presence of calcium chloride or lanthanum chloride. A practical preparation of erythro-α,β-epoxy alcohols
erythro-Epoxy alcohols were prepared with high stereoselectivity by NaBH4 reduction of the corresponding α,β-epoxyketones in the presence of calcium chloride or lanthanum chloride regardless of the substituents on the epoxide ring.
α,β-Epoxyketones are reduced by trimethoxysilane in the presence of a catalytic amount of lithium methoxide to yield the corresponding alcohols. This reaction system reveals divergent selectivity depending on the solvent; both anti-selectivity and syn-selectivity are observed iin less polar Et2O and in polar HMPA, respectively.
Stereoselective Reduction of α,β-Epoxy Ketones into erythro-α,β-Epoxy Alcohols with Sodium Borohydride in the Presence of Calcium Chloride
作者:Hideaki Fujii、Koichiro Oshima、Kiitiro Utimoto
DOI:10.1246/cl.1992.967
日期:1992.6
erythro-α,β-Epoxyalcohols were prepared with high stereoselectivity by sodium borohydride reduction of the corresponding α,β-epoxyketones in the presence of calcium chloride or manganese(II) chloride regardless of the substituents on the epoxide ring.
无论环氧化物环上的取代基如何,在氯化钙或氯化锰 (II) 存在下,通过硼氢化钠还原相应的 α,β-环氧酮,以高立体选择性制备赤型-α,β-环氧醇。