Visible Light Promoted β-C-H Alkylation of β-Ketocarbonyls <i>via</i>
a β-Enaminyl Radical Intermediate
作者:Dehong Wang、Long Zhang、Sanzhong Luo
DOI:10.1002/cjoc.201700785
日期:2018.4
carbonyl activation mode is reported on the basis of photo‐induced single‐electron‐transfer (SET) oxidation of a secondary enamine. The resultant β‐enaminyl radical intermediate was trapped by a wide range of Michael acceptors, producing β‐alkylation products of β‐ketocarbonyls in a highly efficient manner.
Enantioselective synthesis of spiro[4.4]non- and spiro[4.5]dec-2-ene-1,6-diones
作者:B. Chitkul、Y. Pinyopronpanich、C. Thebtaranonth、Y. Thebtaranonth、W.C. Taylor
DOI:10.1016/s0040-4039(00)79975-8
日期:1994.2
Spiro[4.4]non- and spiro[4.5]dec-2-ene-1,6-diones [2; n = 0 and 1] were prepared in moderate to high enantiomeric purities via asymmetric allylation of enamines 6 and ketal derivatives 7 and 8 formed from keto-esters 5, followed by a carbanionic cyclization process.
螺[4.4]非螺和螺[4.5]癸-2-烯-1,6-二酮[ 2 ; n = 0和1]通过烯胺6和由酮酸酯5形成的缩酮衍生物7和8的不对称烯丙基化,以中等至高对映体纯度进行制备,然后进行碳负离子环化过程。
Asymmetric nucleophilic addition of chiral β - enamino esters to acrylonitrile
作者:André Guingant、Hedi Hammami
DOI:10.1016/s0957-4166(00)86008-5
日期:1993.1
β - enamino esters derived from β - keto esters and (S)-1- phenylethytamine, react with acrylonitrile in the presence of a Lewis acid or under high pressure activation to give, after hydrolytic work up, α,α- disubstituted β - keto esters 4 (EWG=CN) in enantiomeric excesses close lo 90%.
Addition of 2-nitropropene to the chiral imine derived from 2-methylcyclopentanone and (S)-1-phenylethylamine furnished the expected Michael adduct. The latter compound was then efficiently converted into (R)-pentalenone through a Nef reaction. Condensation of the enamino ester derived from 2-carbethoxycyclopentanone and (S)-1-phenylethylamine with 1-nitropropene gave with excellent diastereo- and enantioselectivity the corresponding Michael adduct. (C) 1999 Elsevier Science Ltd. All rights reserved.
Enantioselective Access to Five- and Six-membered Nitrogen-containing Heterocycles, Based on the Asymmetric Michael Addition of Chiral Imines and Chiral Enamino Esters
The addition reaction of chiral imines, (ent-10, 48, 70) and chiral enamino esters (52, 55, 73) with maleic anhydride (32), citraconic anhydride (57), alpha-chloroacrylonitrile (29), and nitroethylene (74), has been investigated. These condensations proved to be in general highly regio-, diastereo-, and enantioselective. In most cases the primary adducts underwent an in situ N-heterocyclization, allowing the enantioselective access to nitrogen-containing, five- and six-membered heterocycles.