Carbon Dioxide as a Protecting Group: Highly Efficient and Selective Catalytic Access to Cyclic<i>cis</i>-Diol Scaffolds
作者:Victor Laserna、Giulia Fiorani、Christopher J. Whiteoak、Eddy Martin、Eduardo Escudero-Adán、Arjan W. Kleij
DOI:10.1002/anie.201406645
日期:2014.9.22
The efficient and highly selective formation of a wide range of (hetero)cyclic cis‐diol scaffolds using aminotriphenolate‐based metal catalysts is reported. The key intermediates are cyclic carbonates, which are obtained in high yield and with high levels of diastereo‐ and chemoselectivity from the parent oxirane precursors and carbon dioxide. Deprotection of the carbonate structures affords synthetically
Catalytic Asymmetric Ring-Opening Reaction of<i>meso</i>-Epoxides with Aryl Selenols and Thiols Catalyzed by a Heterobimetallic Gallium-Titanium-Salen Complex
Abstractmagnified imageA chiral heterobimetallic Lewis acid complex has been developed as an efficient catalyst. The enantioselective desymmetrization of meso‐epoxides with aryl selenols and thiols catalyzed by the heterobimetallic complex has been optimized. The optically active β‐arylseleno alcohols and β‐hydroxy sulfides were obtained in good yields and high enantioselectivities (up to 97% ee and 92% ee, respectively). A strong synergistic effect between different Lewis acids was exhibited in the catalytic process.
Rhodium acetate-catalyzed aerobic Mukaiyama epoxidation of alkenes
作者:Dmitry Shabashov、Michael P. Doyle
DOI:10.1016/j.tet.2013.09.062
日期:2013.11
Mukaiyama epoxidation of alkenes under oxygen catalyzed by rhodium acetate with isobutyraldehyde as the reducing agent is as or more effective than previously reported procedures. A variety of alkenes, including terpenes and cholesterol derivatives, were oxidized. And high regioselectivity for mono-epoxidation was observed with neryl, geranyl, and linalyl acetates. (C) 2013 Elsevier Ltd. All rights reserved.