Highly Enantioselective Ring Opening of Cyclic Meso-Anhydrides to Isopropyl Hemiesters with Ti−TADDOLates: An Alternative to Hydrolytic Enzymes?
摘要:
The Lewis acid mediated transfer of an alkoxide ligand from the chiral ligand sphere of Ti-TADDOLate (1) to cyclic meso anhydrides to afford the corresponding hemiesters is described. By using this method a variety of structurally different anhydrides can be converted to isopropyl hemiesters with high enantioselectivities (enantiomer ratios up to 99:1). We have also investigated Lewis acidic titanium complexes, which differ from 1 in the chiral ligand or the alkoxide ligand that is transferred. Finally, a catalytic version, which allows the substoichiometric use of Ti-TADDOLate in the presence of stoichiometric amounts of Al(Oi-Pr)(3), is presented.
Solvent-Free Asymmetric Anhydride Opening in a Ball Mill
作者:Toni Rantanen、Ingo Schiffers、Carsten Bolm
DOI:10.1021/op6002743
日期:2007.5.1
The mechanochemical technique of ballmilling has been applied to the asymmetric opening of meso-anhydrides, mediated by the cinchona alkaloid quinidine. A simple workup procedure affords the products, optically active dicarboxylic acid monoesters, in high yields, with up to 64% ee. With most substrates no column chromatography was needed. A range of various alcohols, as well as anhydrides, reacted
Diorganotin complexes of monoisopropyl and monomethyl nadiate, succinate, and phthalate were synthesized and characterized by elemental analysis, FT-IR, H-1 NMR, C-13 NMR, and Sn-119 NMR spectroscopic techniques. The spectroscopic investigation demonstrated that carboxylate is bidentate in the diorganotin complexes. On the basis of (1)J(Sn-119-C-13) and (2)J(Sn-119-H-1) values, C-Sn-C bond angles were also calculated. The newly synthesized complexes were also screened for their antibacterial activities against Gram-positive and Gram-negative pathogenic strains of bacteria.
A Novel Cost-Effective Thiourea Bifunctional Organocatalyst for Highly Enantioselective Alcoholysis of<i>meso</i>-Cyclic Anhydrides: Enhanced Enantioselectivity by Configuration Inversion
作者:Su-Xi Wang、Fen-Er Chen
DOI:10.1002/adsc.200800761
日期:2009.3
Abstractmagnified imageA novel inexpensive thiourea bifunctional organocatalyst which can promote the highly enantioselective (up to 95% ee) alcoholysis of meso‐cyclic anhydrides has been developed. Computational studies on the catalytic process as well as a synthetic application of this new catalyst are also presented.
Seebach, Dieter; Jaeschke, Georg; Wang, Yan Ming, Angewandte Chemie, 1995, vol. 107, # 21, p. 2605 - 2606
作者:Seebach, Dieter、Jaeschke, Georg、Wang, Yan Ming
DOI:——
日期:——
Synthesis of 3,5,7-Trioxapentacyclo[7.2.1.0<sup>2,8</sup>.0<sup>4,11</sup>.0<sup>6,10</sup>]dodecane. A Novel Diacetal Trioxa-Cage
作者:Shih-Hwa Tsai、Hsien-Jen Wu、Wen-Sheng Chung
DOI:10.1002/jccs.199600064
日期:1996.10
Abstract3,5,7‐Trioxapentacyclo[7.2.1.02,8.04,11.06,10]dodecane, the parent compound of novel diacetal trioxa‐cages, was synthesized from maleic anhydride cyclopentadiene adduct 1 by a four‐step sequence. Attempts for the synthesis of monoaza dioxa‐cage 12 failed. Ozonolysis of compound 9 in CH2Cl2‐EtOH(1:1) at −78°C followed by reduction with Me2S gave 13 in 65% yield.