Photochemistry of Diaryl Vicinal Tetraketones and Chemistry of Intermediate (Aroyloxy)arylketenes(1).
Photolysis of diaryl vic-tetraketones results in formation of tricyclic-gamma-lactones 3 and 4 with low quantum but high chemical yield. (Aroyloxy)arylketenes and carbon monoxide are the initial photochemical products of these photolyses. Subsequent reaction of ketene with ground-state tetraketone results in formation of the observed photoproducts via intermediate beta-lactones. The latter are formed with a high degree of stereoselectivity. The failure of a cyclic tetraketone to react is attributed to its inability to undergo the cyclic mechanism proposed for formation of ketenes from tetraketones. Dimesityl and di-tert-butyl tetraketones react by a competing intramolecular hydrogen atom transfer mechanism. Dimerization of (benzoyloxy)phenylketene and its reactions with a number of tetraketones are described.
Rubin
Mordecai B.
MB
Department of Chemistry, Technion - Israel Institute of Technology, Haifa, Israel and Institute für Organische Chemie, Hagenring 30, D-3300 Braunschweig, Germany.
Etinger
Marina
M
Kapon
Moshe
M
Krochmal
Eric C.
EC
Monosov
Raisa
R
Wierlacher
Stephan
S
Sander
Wolfram
W