Les lactames bicycliques chiraux 派生 de l'oxa-4 aza-1 bicyclo [3.3.0]octanone-8 子前体 tres utiles de center carbones quaternairesgeneres avec une enantioselectivite elevee
Les lactames bicycliques chiraux 派生 de l'oxa-4 aza-1 bicyclo [3.3.0]octanone-8 子前体 tres utiles de center carbones quaternairesgeneres avec une enantioselectivite elevee
Les lactames bicycliques chiraux derives de l'oxa-4 aza-1 bicyclo [3.3.0] octanone-8 sont des precurseurs tres utiles de centres carbones quaternaires generes avec une enantioselectivite elevee
Les lactames bicycliques chiraux 派生 de l'oxa-4 aza-1 bicyclo [3.3.0]octanone-8 子前体 tres utiles de center carbones quaternairesgeneres avec une enantioselectivite elevee
Synthesis of chiral 4,4-disubstituted-dihydropyridazines
作者:Paul T. Buonora、Qun Zhang、Jennifer Sawko、Larry J. Westrum
DOI:10.1016/j.tetasy.2007.11.026
日期:2008.1
In this paper, a novel general route to the stereospecificsynthesis of chiral dihydropyridazines relying on the stereospecific formation of 1,4-diones is presented. The chirality is provided through the application of bicyclic lactams to the synthesis of the required diones. Treatment of the diones with hydrazine produces the pyridazine targets. In this report, the synthesis of four chiral 6-phenyl-4
Single and Double Diastereoselection in Azomethine Ylide Cycloaddition Reactions with Unsaturated Chiral Bicyclic Lactams
作者:Andrew H. Fray、A. I. Meyers
DOI:10.1021/jo9600870
日期:1996.1.1
Double diastereoselectivity data were analyzed to provide insight into the structural features that influence pi-facial selectivity in 1,3-dipolar cycloadditions of chiral and achiral azomethine ylides to chiral, unsaturated bicyclic lactams. Three major steric contributions to the differences in stability (Delta Delta G(double dagger)) between competing cycloaddition transition states were identified. The first major set of steric interactions involve that between the dipoles and the substituents on the left hemisphere (R(2)) and concave faces of the bicyclic lactams. This effectively hindered both alpha- and beta-approaches in the nonextended transition states shown in Figure 1. The second major steric interaction was provided by the nonbonded interactions (i) between the R(1) angular substituent on the bicyclic lactam and the pi-system of the dipole as shown in Figures 3 and 4. This interaction was shown to be very significant, causing reversal in pi-facial attack of chiral and achiral dipoles when the angular substituent is changed from phenyl or methyl to hydrogen. The high diastereoselectivity observed now opens a route to highly substituted chiral, nonracemic pyrrolidines.
Conversion of γ-bicyclic lactams to 4,5-dihydro-2H-pyridazin-3-ones
作者:Yu Jin Lim、Mia Angela、Paul T. Buonora
DOI:10.1016/j.tetlet.2003.08.071
日期:2003.10
Bicyclic lactams are uniquely suited as precursors for the synthesis of chiral substituted 4,5-dihydro-2H-pyridazinones. This paper describes the development of a method for the direct conversion of unsubstituted and 4-substituted gamma-bicyclic lactams to 4,5-dihydro-2H-pyridazin-3-ones and 2-phenyl-4,5-dihydro-2H-pyridazin-3-ones. (C) 2003 Elsevier Ltd. All rights reserved.
MEYERS, A. I.;WALLACE, RICHARD H.;HARRE, MICHAEL;CARLAND, ROBERT, J. ORG. CHEM., 55,(1990) N0, C. 3137-3143
作者:MEYERS, A. I.、WALLACE, RICHARD H.、HARRE, MICHAEL、CARLAND, ROBERT