Formation of α-dialkylamino alkyllithium intermediates in the reaction of N,N-dialkylamides with PhMe2SiLi followed by a second lithium reagent, and their alkylation, fragmentation, cyclisation and rearrangement by proton transfer
The electrode reaction taking place at the first reduction step involves cleavage of the carbon–sulfurbond, resulting in formation of acetophenone and the corresponding thiols in good yields even in an acetonitrile solution containing no proton donor. The second reduction step corresponds to the reduction of the acetophenone produced.
Scope and stereochemistry of an olefin synthesis from β-hydroxysulphones
作者:Philip J. Kocienski、Basil Lythgoe、Steven Ruston
DOI:10.1039/p19780000829
日期:——
The synthesis of olefinsfrom β-acyloxy-sulphones by reduction with sodium amalgam in methanol–ethyl acetate can be applied to the preparation of a wide variety of conjugated dienes. When used for the synthesis of 1,2-disubstituted olefins in which the new double bond is either isolated or conjugated, the reaction is highly stereoselective, and leads to the trans-isomers.
A synthesis of (+)-milbemycin β<sub>3</sub>. The 3,4-dihydro-2H-pyran approach
作者:Clive Yeates、Stephen D. A. Street、Philip Kocienski、Simon F. Campbell
DOI:10.1039/c39850001388
日期:——
Nucleophilic scission of oxirane (8) by vinyl alanate (4) and oxirane (11) by metallated 3,4-dihydro-2H-pyran (15) were key steps in the synthesis of (+)-milbemycin β3(1).
Thermolyses of pentacoordinate 1,2-oxasiletanides with or without a neopentyl group at the 3-position in the presence of a proton source afforded the corresponding olefin and/or alcohol, indicating that they are the intermediates of both the Peterson reaction and homo-Brook rearrangement which are two possible modes in the reaction of β-hydroxyalkylsilanes with bases.
Thiomethyl nickel complexes [Ni(CH2SR)2(PBu3)2] (R = Me (1a), ’Bu (1b), Ph (1e)) and the homoleptic derivatives [Li(Et2O)}2Ni(CH2S’Bu)4] (2), [Li2Ni(CH2SMe)4] · x thf (3a) and [Li2Ni(CH2SPh)4] · x Et2O (3b) were synthesized by the reaction of nickel halide phosphine complexes with the appropriate thiomethyl lithium compounds LiCH2SR in a molar ratio of 1/2 and 1/4, respectively. The molecular structures
硫代甲基镍络合物[Ni(CH 2 SR)2(PBu 3)2 ](R = Me(1a),'Bu(1b),Ph(1e))和均配衍生物[Li(Et 2 O)} 2 Ni(CH 2 S'Bu)4 ](2),[Li 2 Ni(CH 2 SMe)4 ]· x thf(3a)和[Li 2 Ni(CH 2 SPh)4 ]· x Et 2 O(3b)通过卤化镍膦配合物与合适的硫代甲基锂化合物LiCH 2 SR的摩尔比分别为1/2和1/4的反应合成)。反磁性杂配体衍生物1的分子结构(X射线)显示出具有正方形平面的NiC 2 P 2单元的C 1对称性。配体以转位方式排列。配合物1通过微量分析和NMR光谱来表征。的叔-butylthiomethyl复杂2是在室温下稳定(Ť癸〜60–66°C),而甲基和苯基硫代甲基络合物3a和3b已在-10至-20°C时分解。配合物2的分子结构(X射线)显示四个亚甲基碳原子和镍的平面排列略有扭曲(d(Ni-C)=