T. Karatsu et al., PHOTOINDUCED ELECTRON-TRANSFER REACTION OF PYRAZOLINE DERIVATIVES - FORMATION OF REARRANGEMENT PRODUCT, Journal of organic chemistry, 60(25), 1995, pp. 8270-8277
The initial process of photoinduced electron transfer (PET) between el
ectron deficient sensitizers and -substituted-phenyl)-3,5,5-trimethyl-
1-pyrazolines 1 was investigated. Fluorescence quenching rate constant
s of the sensitizers by 1 and PET decomposition quantum yields of 1 re
flect that the stability of the generated radical cations of 1 and the
back-electron transfer play important roles in the reactivity. The ge
nerated radical cations of 1 followed by nitrogen elimination gave cyc
lopropane derivatives 2 and/or aryl migrated olefins 3. Product distri
butions between the cyclopropanes 2 and the olefins 3 depend on the pa
ra-substituent of the phenyl ring of 1. Semiempirical MO calculations
(AM1) of the radical cations of 1 suggest the location of the spin and
the charge governing the product distribution.