Open AccessArylhydrazine Trapping of Benzynes: Mechanistic Insights and a Route to Azoarenes
Author(s) -
Dorian S. Sneddon,
Thomas R. Hoye
Publication year - 2021
Publication title -
organic letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.94
H-Index - 239
eISSN - 1523-7060
pISSN - 1523-7052
DOI - 10.1021/acs.orglett.1c00897
Subject(s) - chemistry , aryne , nucleophile , substituent , reactivity (psychology) , selectivity , trapping , oxygen atom , computational chemistry , medicinal chemistry , stereochemistry , combinatorial chemistry , molecule , organic chemistry , catalysis , medicine , ecology , alternative medicine , pathology , biology
Arylhydrazines (ArN α HN β H 2 ) are ambident nucleophiles. We describe here their reactivity with benzynes generated in situ by thermal cyclization of several multiynes. Products arising from attack of both the alpha- and beta-nitrogen atoms are observed. These competitive modes of reaction were explored by DFT calculations. Substituent effects on the site-selectivity for several substituted phenylhydrazines were explored. Interestingly, the hydrazo products from beta-attack (ArNHNHAr') can be oxidized, sometimes in situ by oxygen alone, to give structurally complex, unsymmetrical azoarenes (ArN═NAr'). Toluenesulfonohydrazide and benzohydrazide analogues were each demonstrated to undergo similar transformations, including oxidation to the corresponding benzyne-trapped azo compounds.