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The diels‐alder reaction of 5‐aminopyrazole‐4‐carbonitrile with dmad: Synthesis and structural determination of dimethyl 2‐( p ‐toluenesulfonylamino)‐3‐cyano‐4‐imino‐1,4‐dihydropyridine‐5,6‐dicarboxylate
Author(s) -
Tominaga Yoshinori,
Castle Raymond N.,
Kent Dalley N.
Publication year - 1993
Publication title -
journal of heterocyclic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.321
H-Index - 59
eISSN - 1943-5193
pISSN - 0022-152X
DOI - 10.1002/jhet.5570300153
Subject(s) - chemistry , pyridine , dimethyl sulfoxide , cycloaddition , pyrazole , adduct , ring (chemistry) , diels–alder reaction , medicinal chemistry , potassium carbonate , diene , stereochemistry , organic chemistry , catalysis , natural rubber
The Diels‐Alder reaction of 5‐amino‐1‐( p ‐toluenesulfonyl)pyrazole‐4‐carbonitrile with dimethyl acetylenedi‐carboxylate was carried out in the presence of potassium carbonate in dimethyl sulfoxide. The reaction gave dimethyl 2‐( p ‐toluenesulfonylamino)‐3‐cyano‐4‐imino‐1,4‐dihydropyridine‐5,6‐dicarboxylate. The product was formed by transformation of the original Diels‐Alder adduct followed by rearrangement of the p ‐toluenesul‐fonylamino group into the 2‐position of the pyridine ring. The structure of the product was irrefutably established by X‐ray crystallography. This reaction is the first example of a pyrazole ring serving as the diene in a [4 + 2] cycloaddition reaction.