The reaction of bis(trifluoromethyl)amino-oxyl with t-butyl bromide, t-butyl chloride, 2,2-dichloropropane, 2-chloro-2-phenylpropane and t-butyl acetate

Article abstract of DOI:10.1016/0022-1139(93)02980-S

Reaction of the oxyl (CF3)2NO(.) (1) with t-butyl bromide (c. 2:1 molar ratio) at room temperature results in initial hydrogen abstraction to give the hydroxylamine (CF3)2NOH (3) and the radical (.)CH2CMe2Br (17) which (i) couples with oxyl 1 to afford the compound (CF3)2NOCH2CMe2Br (6) (33.5percent) and (ii) eliminates a bromine atom to give the alkene CH2=CMe2.Addition of oxyl 1 and bromine to the alkene affords the adducts (CF3)2NOCH2CMe2ON(CF3)2 (4) (10percent) and CH2BrCMe2Br (8) (26.5percent), respectively, while allylic hydrogen abstraction from the alkene leads to the compounds <(CF3)2NOCH2>2CMeON(CF3)2 (5) (10percent) and (CF3)2NOCH2CMeCH2Br (7) (15.5percent).Reaction with t-butyl chloride is more complex and gives a number of unidentified products together with the compounds 4 (37percent), 5 (8percent) and (CF3)2NOCH2CMeCH2Cl (9) (3.5percent) formed by an analogous reaction pathway, although the large amount of hydrogen chloride (61percent) isolated indicates that hydrogen abstraction by chlorine atoms competes with abstraction by oxyl 1.With 2,2-dichloropropane, reaction with the oxyl 1 is slow (even at 70-80 deg C) and gives mainly hydrogen chloride, hydroxylamine 3 (32percent), the substitution product (CF3)2NOCH2CCl2CH3 (10) (42percent) and the 2:1 adduct of oxyl 1 and the alkene CH2=CMeCl, i.e. (CF3)2NOCH2CMeClON(CF3)2 (11) (24percent).In contrast, reaction involving 2-chloro-2-phenylpropane is facile at room temperature and affords hydrogen chloride (97.5percent), hydroxylamine 3 (12.5percent) and the 2:1 adduct (CF3)2NOCH2CMePhON(CF3)2 (12) (78percent) of oxyl 1 and the alkene CH2=CMePh.Treatment of t-butyl acetate with oxyl 1 gives hydroxylamine 3 (49percent), the oxadiazapentane (CF3)2NON(CF3)2 (2) (9percent) and the compounds (CF3)2NOCH2CMe2OAc (14) (36percent), <(CF3)2NO>2CHCMe2OAc (15) (15percent) and (CF3)2NO2CCMe2OAc (16) (40percent) formed via successive oxyl 1 attack on a methyl group.In these reactions, compounds arising via a 1,2-shift of bromine, chlorine or acetate were not detected in the products.