A stereocontrolled approach to electrophilic epoxides
作者:Otto Meth-Cohn、Clive Moore、Heinrich C. Taljaard
DOI:10.1039/p19880002663
日期:——
Lithium t-butyl hydroperoxide (easily generated by addition of an alkyl-lithium to anhydrous t-butyl hydroperoxide in THF solution) is a powerful reagent for the epoxidation of electrophilic alkenes at –20 to 0 °C under full stereocontrol.
A Convenient Synthesis of Enantiomerically Pure (2<i>S</i>,3<i>S</i>)- or (2<i>R</i>,3<i>R</i>)-3-Hydroxyleucine
作者:Charles G. Caldwell、Steven S. Bondy
DOI:10.1055/s-1990-26779
日期:——
Both enantiomers of erythro-3-hydroxyleucine are available by asymmetric epoxidation of (E)-4-methyl-2-penten-1-ol (1) followed by ruthenium tetroxide catalyzed oxidation to the corresponding glycidic acid 3, epoxide opening by benzylamine, and hydrogenolysis using palladium hydroxide on carbon.
Reaction of a wide variety of aldehydes with the easily prepared 2-azadienes, in the presence of BF3 etherate, furnishes the corresponding hetero Diels-Alder adducts which have been converted, mainly, to cis epoxides via N-Boc protection followed by one-pot two-step ring opening and nucleophilic displacement of the halogen atom, resulting in final formation of an oxirane ling. (C) 2004 Elsevier Ltd. All rights reserved.
Efficient chemoenzymatic synthesis of (2S,3S )-3-hydroxyleucine mediated by immobilised penicillin G acylase †
作者:Nitin W. Fadnavis、Mohd. Sharfuddin、S. Kumara Vadivel、Uday T. Bhalerao
DOI:10.1039/a707507c
日期:——
Immobilised penicillin G acylase (EC 3.5.1.11) has been used in the key step to obtain optically pure (2S,3S)-(+)-hydroxyleucine (ee >99%).