Enantioselective Conjugate Addition of Hydrazines to α,β-Unsaturated Imides. Synthesis of Chiral Pyrazolidinones
作者:Mukund P. Sibi、Takahiro Soeta
DOI:10.1021/ja069312d
日期:2007.4.1
This manuscript describes a highlyenantioselectiveconjugate hydrazine addition to α,β-unsaturatedimides. The achiral template used has a significant impact on product enantioselectivity. Reactions at lower temperatures provide a protocol to add substituted hydrazines with selectivity resulting in the formation of a single pyrazolidinone product (>98:2 selectivity). A variety of chiral pyrazolidinones
Strategy To Prepare 3-Bromo- and 3-Chloropyrazoles
作者:Richard J. Fox、Michael A. Schmidt、Martin D. Eastgate
DOI:10.1021/acs.joc.7b03282
日期:2018.3.2
A general strategy to prepare substituted 3-bromo- and 3-chloropyrazoles is described. The three-step method involves condensation of crotonates or β-chloro carboxylic acids with hydrazines, followed by halogenation and oxidation. Several condensation and oxidation protocols were developed to enable preparation of a wide variety of 3-halopyrazoles with good to excellent yields and regiocontrol.
Structural effects in pyrazolidinone-mediated organocatalytic Diels–Alder reactions
作者:Eoin Gould、Tomas Lebl、Alexandra M.Z. Slawin、Mark Reid、Andrew D. Smith
DOI:10.1016/j.tet.2010.09.021
日期:2010.11
promoted Diels–Alderreactions evaluated. Systematic variation of the C(5)- and N(2)-substituents indicates that the incorporation of an electron withdrawing substitutent at N(2) and either a Ph or CF3 substitution at C(5) results in optimal catalytic activity. The diastereoisomeric resolution of a model C(5)-Ph substituted pyrazolidinone and its ability to impart modest levels of asymmetric induction