New aspects of diphenylbutadiene photochemistry. Regiospecific hula-twist photoisomerization.
In EPA glass at liquid nitrogen temperature, the E,E isomer of diphenylbutadiene (DPB) was photostable, while both the Z,E and Z,Z isomers underwent selective HT isomerization at center 1 giving the stable conformer of the double-bond isomerized trans product. That HT-1 was involved rather than the OBF process was shown by results of o,o'-dimethyl-DPB. Formation of unstable trans product corresponded to simultaneous configurational and conformational isomerization. The regioselectivity was found not sensitive to a substituent effect, as shown by the similar reactivity in p,p'- or o,o'-bistrifluoromethyl-DPB.
Yang
Lan-Ying
LY
Department of Chemistry, University of Hawaii, 2545 The Mall, Honolulu, Hawaii 96822, USA.
Liu
Robert S H
RS
Boarman
Kelly J
KJ
Wendt
Natalie L
NL
Liu
Jin
J