162375-38-4Relevant academic research and scientific papers
Regioselective Thermal [3+2]-Dipolar Cycloadditions of α-Diazoacetates with α-Sulfenyl/Sulfinyl/Sulfonyl-β-Chloroacrylamide Derivatives to Form Densely Functionalised Pyrazoles
Flynn, Aaran J.,Ford, Alan,Khandavilli, U. B. Rao,Lawrence, Simon E.,Maguire, Anita R.
, p. 5368 - 5384 (2019/06/24)
Highly regioselective synthetic methodology leading to densely functionalised C(3), C(4) and C(5) substituted pyrazoles 10a–q, 14a-i and 16a–g 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 sulfide and sulfone oxidation levels, while elimination of the sulfinyl group leading to 3,5-disubstituted pyrazoles, is observed. While the sulfide migration is readily rationalised, the carbon to carbon 1,2-sulfonyl migration is unprecedented and mechanistically intriguing. The synthetically versatile generation of densely functionalised pyrazoles containing substituents amenable to further modification offers advantages over alternative synthetic routes. Isolation of the N-alkylated pyrazoles 11a and 12a as by-products from the cycloaddition through further reaction of the pyrazoles 10 with excess α-diazoacetate, proved useful in rationalising the tautomeric behaviour evident in the NMR spectra of the pyrazoles, with the position of tautomeric equilibrium influenced by solvent and substituents.
Investigation of the synthetic and mechanistic aspects of the highly stereoselective transformation of α-thioamides to α-thio-β- chloroacrylamides
Murphy, Maureen,Lynch, Denis,Schaeffer, Marcel,Kissane, Marie,Chopra, Jay,O'Brien, Elisabeth,Ford, Alan,Ferguson, George,Maguire, Anita R.
, p. 1228 - 1241 (2008/02/03)
Treatment of a series of α-thioamides with N-chlorosuccinimide results in efficient transformation to the analogous α-thio-β- chloroacrylamides. The mechanistic pathway has been established through isolation and characterisation of intermediate compounds. The scope of the transformation has been explored - aryl and alkylthio substituents, primary, secondary and tertiary amides can be employed. In most instances, the chloroacrylamides are formed exclusively as the Z-stereoisomer; however, with tertiary propanamides or with amides derived from butanoic or pentanoic acid a mixture of E- and Z-stereoisomers is formed. The Royal Society of Chemistry.
Single Step Stereospecific Transformation of 2-Phenylthio Secondary Amides into (Z)-3-Chloro-2-Phenylthio Acrylamides
Maguire, Anita R.,Murphy, Maureen E.,Schaeffer, Marcel,Ferguson, George
, p. 467 - 470 (2007/10/02)
α-Phenylthio secondary propanamides 1a-e are converted stereospecifically on treatment with NCS to the analogous (Z)-α-phenylthio-β-chloro propenamides 2a-e.Extension to longer chain secondary amide derivatives 1f-g is also possible, albeit less efficient
