95184-19-3Relevant academic research and scientific papers
Photorearrangement Studies of 3-Heteroaryl-substituted Cyclopropenes
Padwa, Albert,Chiacchio, Ugo,Compagnini, Anna,Corsaro, Antonino,Purrello, Giovanni
, p. 2671 - 2676 (2007/10/02)
The photochemical rearrangement of several 3-heteroaryl-substituted cyclopropenes containing a methyl group on the heterocyclic ring has been studied.The rearrangements are derived from the ? - ?*singlet state of the cyclopropene.Ring-opening occurs to give a vinylcarbene intermediate which undergoes a subsequent electrocyclization.The resulting product was found to undergo a sigmatropic 1,5-methyl shift on being heated in mesitylene at 200 deg C to give a cyclopentafuran or thiophene.Yet another reaction resulting from the vinylcarbene is insertion into the adjacent methyl group to give a buta-1,3-diene derivative.The product distribution is dependent on the stereochemistry of the vinylcarbene.Irradiation of 1,2-diphenyl-3-heteroaryl-substituted cyclopropenes also give products corresponding to a 1,2-heteroaryl substituent shift.A mechanism involving ? -?* bridging of the excited cyclopropene with the heteroaromatic ring followed by diradical cleavage is proposed to account for the formation of the rearranged cyclopropenes.
