Enantioselective Hydroazidation of Trisubstituted Non-Activated Alkenes
作者:Daniel Meyer、Philippe Renaud
DOI:10.1002/anie.201703340
日期:2017.8.28
A one-pot procedure for the enantioselective hydroazidation of non-activated trisubstituted alkenes is described. Hydroboration with monoisopinocampheylborane (IpcBH2) provides dialkylboranes that are in situ selectively converted into monoalkyl-substituted catecholboranes; these undergo radical azidation upon treatment with benzenesulfonyl azide and a radical initiator. Enantiomerically enriched azides
Organolithium reagents effect a regioselective SN2 nucleophilic cleavage of α,β-ethylenic epoxides only when BF3·Et2O is added. The reaction works with a variety of RLi reagents and with cyclic as well as acyclic epoxides.
The use of trialkylorganozincates and tetraalkylaluminates allows regioselective SN2 nucleophilic opening of vinylic epoxides. The reaction occurs with an anti-substitution pattern and can be applied to a wide range of substrates. We also show that the solvent and the structure of the epoxide have an influence on the substitution products ratio.
The copper-catalysedringopening of epoxides and oxetane by Grignard reagents proceeds in good yield under mild conditions.
在温和条件下,格氏试剂在铜催化的环氧化物和氧杂环丁烷的开环反应中收率很高。
Synthesis of Chiral Cyclic Alcohols from Chiral Epoxides by H or N Substitution with Frontside Displacement
作者:Roberto da Silva Gomes、Karla Mahender Reddy、E. J. Corey
DOI:10.1021/acs.orglett.8b02822
日期:2018.10.5
Diverse examples are provided of enantioselective sequences for the transformation of cycloalkenes to either chiral trans-β-substituted cycloalkanols or chiral α-amino ketones.