62756-33-6Relevant academic research and scientific papers
Photolysis of 3-bromochroman-4-ones
Consuelo Jiménez,Miranda, Miguel A.,Tormos, Rosa
, p. 339 - 347 (2007/10/03)
Photolysis of 3-bromochroman-4-ones (1a-f) leads to debrominated chromanones (2a-f) and chromones (3a-f) as major products. Their formation is accounted for in terms of primary cleavage of the carbon halogen bond to give α-carbonyl radicals (I) and/or cations (II). In the case of the 2,2-disubstituted compounds (1d-f), intermediates (II) undergo rearrangement with 1,2-shift of the phenyl or benzyl substituent prior to deprotonation. Minor by-products are the pentacyclic pyrone (4e) or 2-methylchromone (3a) (starting from 1e and 1f, respectively).
Electron Transfer Oxidation of Enol Derivatives of 2,3-Dihydrobenzopyran-4-ones
Jimenez, M. Consuelo,Miranda, Miguel A.,Soto, Juan,Tormos, Rosa
, p. 7635 - 7644 (2007/10/02)
Dihydrobenzopyrones 1a-c and their enol acetates 3a-c have been submitted to oxidation under single electron transfer (SET) conditions, using three alternative ways of activation: chemical oxidation with cerium(IV) ammonium nitrate (CAN), photochemical oxidation using triphenylpyrylium tetrafluoroborate (TPT) as sensitizer or electrochemical oxidation.The most significant products obtained are diketones 4, hydroxyketones 5, rearranged benzopyrones 6, enones 9 and, in the case of enol acetate 3c, 2-methylchromone (10) and 1,2-diphenylethane (13).These results are rationalized according to three major pathways from the radical cations: i) formation of the α-carbonyl radicals I (trough deprotonation of the enols 2(+). or cleavage of the carbonyl-oxygen bond of their acetates 3(+).), eventually followed by secondary oxidation to the carbenium ions II, ii) breaking of the bond linking C2 with one of the substituents and iii) ring opening.
