Investigation of the chemoselective and enantioselective oxidation of α-thio-β-chloroacrylamides
摘要:
An investigation of the chemoselective and enantioselective oxidation of alpha-thio-beta-chloroacrylamides is described. The alpha-thio-beta-chloroacrylamides can be selectively oxidised to either the racemic sulfoxide or the sulfone very efficiently. The asymmetric sulfur oxidation of alpha-thio-beta-chloroacrylamides is also discussed, with sulfoxide enantioselectivities of up to 52% ee achieved using the Kagan oxidation, and up to 71% ee when the Bolm oxidation is employed. While the enantioselectivities achieved are modest, these are among the most highly functionalised sulfides investigated in catalytic asymmetric oxidation, and the resulting enantioenriched sulfoxides have significant synthetic potential. (C) 2008 Elsevier Ltd. All rights reserved.
Regioselective Thermal [3+2]‐Dipolar Cycloadditions of α‐Diazoacetates with
<i>α</i>
‐Sulfenyl/Sulfinyl/Sulfonyl‐
<i>β</i>
‐Chloroacrylamide Derivatives to Form Densely Functionalised Pyrazoles
作者:Aaran J. Flynn、Alan Ford、U. B. Rao Khandavilli、Simon E. Lawrence、Anita R. Maguire
DOI:10.1002/ejoc.201900494
日期:2019.9
Highly regioselective synthetic methodology leading to densely functionalised C(3), C(4) and C(5) substituted pyrazoles via thermal [3+2]‐dipolar cycloaddition, of α‐diazoacetates and α‐thio‐β‐chloroacrylamides, at the sulfide, sulfoxide and sulfone levels of oxidation, is described. This method allows access to C(4)‐sulfenyl or sulfonyl pyrazoles, through migration of the sulfur substituent at the