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Cycloaddition of benzothiete and electron‐deficient nitriles
Author(s) -
Schmidt Michael,
Meier Herbert,
Saleh Sadiq A.
Publication year - 1991
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.5570280306
Subject(s) - chemistry , nitrile , cycloaddition , double bond , ring (chemistry) , cleavage (geology) , medicinal chemistry , bond cleavage , electron , stereochemistry , organic chemistry , catalysis , physics , geotechnical engineering , quantum mechanics , fracture (geology) , engineering
The o ‐quinoid 8π electron system 2 , generated by thermal ring opening of benzothiete ( 1 ), enters regio‐specific [8π + 2π] cycloaddition reactions with electron‐deficient nitriles 3a‐d , yielding the 4 H ‐1,3‐benzothiazines 4a‐d. A competitive dimerization of 1 leads to 1,5‐dibenzo[ b,f ]dithiocin (5). Depending on the nitrile further competitive or subsequent reactions (2 + 3b → 7b, 2 + 3d → 4d → 8d) can occur. The cycloadducts 10e and 11e gained from 3e anticipate a primary cleavage of 3e to methylisothiocyanate 9e which reacts at the CN double bond as well as at the CS double bond.