Photolysis of 3-aryl-3-(trifluoromethyl)diazirines: a caveat regarding their use in photoaffinity probes.
The photolysis of 3-(4-tolyl)-3-(trifluoromethyl)diazirine in the presence of benzene, methanol, carbon tetrachloride, cyclohexane, triethylsilane, or diethylamine led to photoproducts consistent with the intermediacy of a singlet carbene. In the case of diethylamine, the photoinsertion into the N-H bond of diethylamine produced the expected adduct, 1-(diethylamino)-2,2,2-trifluoro-1-(4-tolyl)ethane. However, the base-catalyzed elimination of hydrogen fluoride from this adduct afforded an enamine, alpha-(diethylamino)-beta,beta-difluoro-4-methylstyrene, and the subsequent hydrolysis of this enamine furnished diethylamine and 2,2-difluoro-1-(4-tolyl)ethanone. This elimination and hydrolysis sequence effectively reversed the photoinsertion process. A similar photoinsertion and hydrolysis process using 3-(4-n-octylphenyl)-3-(trifluoromethyl)diazirine also produced 2,2-difluoro-1-(4-n-octylphenyl)ethanone in modest yield. These results suggest that the photoinsertion products from 3-aryl-3-(trifluoromethyl)-diazirines in biological systems may suffer similar fates limiting, in part, their utility in obtaining primary sequence data.
Platz
M
M
Department of Chemistry, Ohio State University, Columbus 43210.
Admasu
A S
AS
Kwiatkowski
S
S
Crocker
P J
PJ
Imai
N
N
Watt
D S
DS
D000345:Affinity Labels; D001389:Azirines / Q000737:chemistry*; D010782:Photolysis
D000345:Affinity Labels; D001389:Azirines; C073104:3-(4-tolyl)-3-(trifluoromethyl)diazirine