Enantiocontrol by assembled attractive interactions in copper-catalyzed asymmetric direct alkynylation of α-ketoesters with terminal alkynes: OH⋯O/sp<sup>3</sup>-CH⋯O two-point hydrogen bonding combined with dispersive attractions
作者:Martin C. Schwarzer、Akane Fujioka、Takaoki Ishii、Hirohisa Ohmiya、Seiji Mori、Masaya Sawamura
DOI:10.1039/c8sc00527c
日期:——
Copper-catalyzed asymmetric directalkynylation of α-ketoesters with terminal alkynes with chiral prolinol–phosphine ligands, most preferably (αR,2S)-1-(2-dicyclohexylphosphinobenzyl)-α-neopentyl-2-pyrrolidinemethanol, afforded various enantioenriched chiral propargylic tertiary alcohols. Quantum-chemical calculations using the BP86 density functional including Grimme's empirical dispersion correction
铜催化 α-酮酯与末端炔烃与手性脯氨醇-膦配体,最优选 (α R ,2 S )-1-(2-二环己基膦基苄基)-α-新戊基-2-吡咯烷甲醇的不对称直接炔基化,提供了各种对映体富集的手性炔丙基叔醇。使用 BP86 密度泛函(包括 Grimme 经验色散校正)的量子化学计算 [DF-BP86-D3(BJ)-PCM( t BuOH)/TZVPP//DF-BP86-D3(BJ)/SVP] 显示 OH⋯ 的出现手性配体和处于立体决定过渡态的酮酯的羰基之间的O/sp 3 -CH⋯O两点氢键。结合定向酮酯底物的氢键相互作用,手性配体(P-环己基)和有利过渡态的酮酯之间的色散吸引力,而不是不利过渡态的空间排斥,解释了不对称铜催化的对映选择性。
Enantiocontrolled Synthesis of Tertiary α-Hydroxy-α-ynyl Esters by Dimethylzinc-Mediated Addition of Alkynes to α-Keto Esters
3-benzoxazine behaves as an excellent chiral ligand in the nucleophilicaddition of alkynylzinc derivatives, prepared from terminal alkynes and dimethylzinc, to α-ketoesters without using other Lewis acids. The enantioselectivity is excellent and homogeneous for a wide variety of aromatic and heteroaromatic α-ketoesters. Aliphatic enolizable α-ketoesters were alkynylated with moderate enantioselection.
Highly Enantioselective Alkynylation of <i>α</i>-Keto Ester: An Efficient Method for Constructing a Chiral Tertiary Carbon Center
作者:Biao Jiang、Zili Chen、Xiaoxia Tang
DOI:10.1021/ol026544i
日期:2002.10.1
ester was carried out using a catalytic amount of (1S,2S)-3-(tert-butyldimethylsilyloxyl)-2-N,N-(dimethylamino)-1-(p-nitrophenyl)-propane-1-ol in the presence of Zn(OTf)(2) to give the corresponding tertiary propargylic alcohols in high yields with up to 94% ee. N-Methylephedrine and Zn(OSO(2)CHF(2))(2) were also examined in this reaction. [reaction: see text]
Chiral aminoalcohol promoted one-pot addition of zinc alkynylides to α-keto esters and kinetic resolution of the resulting tertiary propargylic alcohols was developed. The reaction provided us an alternative approach to access optically activetertiary α-hydroxy-β-ynyl esters with enantiomeric excesses up to 98%.