Acceleration of Arylzinc Formation and Its Enantioselective Addition to Aldehydes by Microwave Irradiation and Aziridine-2-methanol Catalysts
摘要:
The formation and 2-amino alcohol catalyzed addition of arylzinc reagents from and with boronic acids, respectively, is drastically accelerated to a few minutes under microwave irradiation without loss of enantioselectivity (up to 98% ee). Of the amino acid derived catalysts tested, the conformationally restricted bulky substituted aziridine-2-methanols derived from serine show the best overall performance in the formation of diarylmethanols.
Highly Enantioselective Direct Aldol Reaction Catalyzed by Organic Molecules
作者:Monika Raj、Vishnumaya、Sandeep K. Ginotra、Vinod K. Singh
DOI:10.1021/ol0616081
日期:2006.8.1
compounds catalyzed the directaldolreaction between aldehydes and acetone to provide beta-hydroxy ketones in good yields. The reaction is efficient, and 5-10 mol % of the catalyst and excellent enantioselectivities (97-99% ee) were obtained in both aromatic and aliphatic aldehydes. The presence of a gem-diphenyl group at the beta-carbon is necessary for high enantioselectivity.
Synthesis of homochiral bis (oxazolinyl) pyridine type ligands for asymmetric cyclopropanation reactions
作者:Arpita Datta Gupta、Debnath Bhuniya、Vinod K. Singh
DOI:10.1016/s0040-4020(01)85684-2
日期:1994.1
Homochiral bis(oxazolinyl)pyridine type ligands were synthesized from (S)-valine and converted into their Cu(II) complexes. Reduction of these Cu(II) complexes into Cu(I) with diazoesters was studied by uv-vis and epr spectroscopy. The enantioselective cyclopropanation reaction was carried out using styrene as a model substrate.
Gupta Arpita Datta, Bhuniya Debnath, Singh Vinod K., Tetrahedron, 50 (1994) N 48, S 13725-13730
作者:Gupta Arpita Datta, Bhuniya Debnath, Singh Vinod K.