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Selective arylation of exocyclic N ‐position of 2‐pyrimidylnitrenium ion photolytically generated from tetrazolo‐[1,5‐a]pyrimidine in the presence of trifluoroacetic acid
Author(s) -
Takeuchi Hiroshi,
Watanabe Keiichi
Publication year - 1998
Publication title -
journal of physical organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.325
H-Index - 66
eISSN - 1099-1395
pISSN - 0894-3230
DOI - 10.1002/(sici)1099-1395(199807)11:7<478::aid-poc27>3.0.co;2-q
Subject(s) - chemistry , trifluoroacetic acid , biphenyl , pyrimidine , benzene , nucleophile , solvent , medicinal chemistry , ion , singlet state , photochemistry , organic chemistry , stereochemistry , catalysis , physics , nuclear physics , excited state
Photo‐reactions of tetrazolo[1,5‐a]pyrimidine ( 1 ) with benzene ( 2a ) and substituted benzenes ( 2b–f ) in the presence of trifluoroacetic acid (TFA) gave 2‐(2‐, 3‐ and 4‐substituted anilino)pyrimidines ( 3–5 ) together with 2‐aminopyridine ( 6 ) and biphenyl ( 7 ) or diarylmethanes ( 8b, 8c and 8e ). From the effect of heavy‐atom solvent on the reactions, it is reasonable to assume that 3–5 are formed via a singlet species, but 6–8 via a triplet species. The intermediacy of 2‐pyrimidylnitrenium ion is consistent with the evidence derived by the above effect, by a Hammett plot with ρ = −2.9 and by effects of solvent nucleophilicity and counter‐anions. The selective exocyclic N ‐arylation giving 3–5 is discussed. © 1998 John Wiley & Sons, Ltd.