Catalytic asymmetric Mannich reaction of glycine Schiff bases with α-amido sulfones as precursors of aliphatic imines
作者:Elier Hernando、Ramón Gómez Arrayás、Juan C. Carretero
DOI:10.1039/c2cc35160a
日期:——
A general and practical Cu(I)-Fesulphos-catalyzed Mannich reaction of glycinate Schiff bases with aliphatic imines generated in situ from alpha-amido sulfones is described. Imines with linear and branched alkyl chains, including substrates bearing functional groups, can be efficiently applied. The resulting syn-configured orthogonally protected beta-alkyl-alpha,beta-diamino acid derivatives are produced
Organocatalytic trifluoromethylation of imines using phase-transfer catalysis with phenoxides. A general platform for catalytic additions of organosilanes to imines
A new approach to additions of silicon nucleophiles to imines was developed. The method is based on the phase-transfer of phenoxides by ammonium catalysts, overcoming the inability of amide adducts in promoting the reactions.
Studies on the synthesis of α-iodoaziridines and improved conditions for the synthesis of alkyl-α-iodoaziridines using ClMgCHI2
作者:Tom Boultwood、Dominic P. Affron、James A. Bull
DOI:10.1016/j.tet.2015.05.098
日期:2015.7
The effects of varying the N-group and using different carbenoids are investigated. Excellent cis-stereochemistry is achieved, except for N-carbamates containing aryl groups. Using the mixed carbenoid LiCHICl, the iodide leaving group is selected for cyclisation affording chloroaziridines only, as a cis/trans mixture. More convenient and higher yielding conditions for the preparation of alkyl N-Ts α-iodoaziridines
Synthesis of <i>cis</i>-<i>C</i>-Iodo<i>-N</i>-Tosyl-Aziridines using Diiodomethyllithium: Reaction Optimization, Product Scope and Stability, and a Protocol for Selection of Stationary Phase for Chromatography
作者:Tom Boultwood、Dominic P. Affron、Aaron D. Trowbridge、James A. Bull
DOI:10.1021/jo400956x
日期:2013.7.5
The preparation of C-iodo-N-Ts-aziridines with excellent cis-diastereoselectivity has been achieved in high yields by the addition of diiodomethyllithium to N-tosylimines and N-tosylimine-HSO(2)Tol adducts. This addition-cyclization protocol successfully provided a wide range of cis-iodoaziridines, including the first examples of alkyl-substituted iodoaziridines, with the reaction tolerating both aryl imines and alkyl imines. An ortho-chlorophenyl imine afforded a beta-amino gem-diiodide under the optimized reaction conditions due to a postulated coordinated intermediate preventing cyclization. An effective protocol to assess the stability of the sensitive iodoaziridine functional group to chromatography was also developed. As a result of the judicious choice of stationary phase, the iodoaziridines could be purified by column chromatography; the use of deactivated basic alumina (activity IV) afforded high yield and purity. Rearrangements of electron rich aryl-iodoaziridines have been promoted, selectively affording either novel alpha-iodo-N-Ts-imines or alpha-iodo-aldehydes in high yield.
A Highly Stereoselective Addition of the Anion Derived from ?-Diazoacetamide to AromaticN-Tosylimines
作者:Yonghua Zhao、Zhihua Ma、Xiaomei Zhang、Yaping Zou、Xianglin Jin、Jianbo Wang