Sequential 1,3-Dipolar Cycloaddition-Pictet–Spengler Reactions. A Versatile Tactical Combination
摘要:
The combination of thermal or Ag(I) catalysed imine-->azomethine ylide-->cycloaddition cascades with a subsequent Pictet-Spengler reaction allows the assembly of polyfunctional N-heterocycles, via formation of 4 bonds and 2 rings, in good yield. (C) 2000 Elsevier Science Ltd. All rights reserved.
Cycloadditions of arylidene imines of α-aminoacidesters to a range of dipolarophiles show substantial rate enhancements in the presence of Bronsted and Lewis acids. For Bronsted acids the rate is related to the pKa of the acid and cycloadditions to reactive dipolarophiles occur at room temperature. For the Lewis acids studied the rate acceleration decreases in the order Zn(OAc)2 > AgOAc > LiOAc >
XY–ZH Systems as potential 1,3-dipoles. Part 8. Pyrrolidines and Δ<sup>5</sup>-pyrrolines (3,7-diazabicyclo[3.3.0]octenes) from the reaction of imines of α-amino acids and their esters with cyclic dipolarophiles. Mechanism of racemisation of α-amino acids and their esters in the presence of aldehydes
Imines of α-aminoacidesters with aromatic, heterocyclic, and aliphatic aldehydes generate azomethine ylides stereospecifically by a prototropic shift on heating in toluene. The azomethine ylides undergo cycloaddition to N-phenylmaleimide, maleic anhydride, and p-naphthoquinone via an endo-transition state to give racemic, single diastereoisomeric, cycloadducts. α-Aminoacids undergo analogous cycloadditions
A new and highly efficient Cu(I)/TF-BiphamPhos catalytic system exhibited excellent reactivity, enantio-/diastereoselectivity, and structural scope in asymmetric 1,3-dipolarcycloaddition of azomethineylides with 0.1-3 mol % of catalyst loading. The present methodology is the best result for asymmetric cycloaddition of azomethineylides, especially derived from amino esters other than glycinate in
作者:H.Ali Dondas、Ronald Grigg、William S MacLachlan、David T MacPherson、Jasothara Markandu、Visuvanathar Sridharan、Selveratnam Suganthan
DOI:10.1016/s0040-4039(99)02183-8
日期:2000.2
Up to six bonds and two rings can be created, in five component processes (five points of diversity), by AgOAc catalysed imine cycloaddition to Wang resin acrylate followed by Pictet-Splengler and Pd(0) catalysed reactions. (C) 2000 Elsevier Science Ltd. All rights reserved.
GRIGG, RONALD;GUNARATNE, H. Q. NIMAL;SRIDHARAN, VISUVANATHAR, TETRAHEDRON, 43,(1987) N 24, 5887-5898
作者:GRIGG, RONALD、GUNARATNE, H. Q. NIMAL、SRIDHARAN, VISUVANATHAR