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Heptafulvenone, Vinylketene, Butadienylketene, and Allenylketene − Facile Generation, Observation, and Radical Reaction with TEMPO
Author(s) -
Tidwell Thomas T.,
Fenwick Michael H.
Publication year - 2001
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/1099-0690(200109)2001:18<3415::aid-ejoc3415>3.0.co;2-w
Subject(s) - chemistry , delocalized electron , naphthalene , dimer , radical , medicinal chemistry , adduct , diradical , ring (chemistry) , photochemistry , stereochemistry , computational chemistry , organic chemistry , excited state , physics , nuclear physics , singlet state
Heptafulvenone ( 1 ), vinylketene ( 11 ), 1,3‐butadienylketene [( E )‐ 15 ], and allenylketene ( 21 ) have been prepared by reaction of the corresponding acyl chlorides with 1,8‐bis(dimethylamino)naphthalene as long‐lived species in solution at room temperature, and their ketenyl IR bands observed under these conditions for the first time, at 2101, 2118, 2111, 2117 cm −1 , respectively. These unsaturated ketenes react with tetramethylpiperidinyloxyl (TEMPO, TO·) with initial attack at the carbonyl carbon giving delocalized radicals which give from 1 a mixture of the ring contracted o‐ , m‐ , and p ‐formylbenzoates O=CHC 6 H 4 CO 2 T ( 6 ) and the bis(cycloheptatrienyl) dimer 7 . The products from 11 , ( E )‐ 15 , and 21 are the bis(TEMPO) adducts ( E,Z )‐TOCH 2 CH=CHCO 2 T ( 12 ), ( E,E )‐TOCH 2 CH=CHCH=CHCO 2 T ( 17 ), and ( E , Z )‐CH 2 =C(OT)CH=CHCO 2 T ( 22 ), respectively.