Reactions of bis(trifluoromethyl)amino-oxyl and perfluoro(2,4-dimethyl-3-oxa-2,4-diazapentane) with non-conjugated dienes and with allylbenzene

Abstract

Reaction of the oxyl (CF 3) 2NO·( 1) with norbornadiene ( 4) (1.6:1 molar ratio, liquid phase or 2:1 molar ratio, solution in CFCl 2CF 2Cl) gave the non-rearranged 2:1 adducts 5- exo-6- endo-bis(bistrifluoromethylamino-oxy)norborn-2-ene ( 13a) (ca. 30%) and its 5- exo-6- exo-isomer ( 13b) (ca.30%), the rarranged 2:1 adducts 3- endo-5- exo-bis(bistrifluoromethylamino-oxy)nortricyclane ( 14a) (ca.10%) and its 3- exo-5- exo isomer ( 14b) (ca.10%) and a mixture of four 4:1 adduct isomers of 2- exo-3,5,6-tetrakis(bistrifluoromethylamino-oxy)norbornane ( 15) (10%–20%); only the four 2:1 adducts were formed in solution using a large excess of the diene (1:19 molar ratio) or in the gas phase (2:1 molar ratio). In contrast, reaction of the oxadiazapentane ( 3) with diene 4 (1.1:1 molar ratio) in solution afforded only telomeric material. The reaction between oxyl 1 and cyclo-octa-1,5-diene ( 5) (1.9:1 molar ratio, −196 °C to ca. 20 °C) gave the hydroxylamine (CF 3) 2NOH ( 17) (43.5%), the allylic substitution product (CF 3) 2NO CHCH=CH(CH 2) 2CH=CH CH 2 ( 19) (30%), two isomeric disubstitution products [(CF 3) 2NO] 2C 8H 10 ( 20) (12.5% and 15.5%) and two diastereomers of the 2:1 adduct (CF 3) 2NO CH(CH 2) 2CH-CH(CH 2) 2 CHON(CF 3) 2 (13.5% and 14.5%). In the corresponding reaction of the oxadiazapentane 3 with diene 5 (ca. 1:1 molar ratio, ca. 20 °C) hydrogen abstraction leading to compound 19 (13%) was less favoured, the major product being the 1:1 adduct (CF 3) 2N CH(CH 2) 2CH-CH(CH 2) 2 CHON(CF 3) 2 , formed as two diastereomers ( 31a) (34%) and ( 31b) (28%); the amine (CF 3) 2N CH(CH 2) 2CH-CH(CH 2) 2 CH 2 ( 32) (9%) was also formed as a minor product. Addition was also favoured in the reaction of oxyl 1 with cyclo-octene ( 6) (1.8:1 molar ratio, −196 to ca. 20 °C), leading to the 2:1 adduct ( 23) (67.5%); hydrogen astrraction led to the allylic substitution product ( 22) in low yield (20%). All of the products isolated from the reaction of oxyl 1 with penta-1,4-diene ( 7) (1.8:1 molar ratio, −78 °C), apart from the 2:1 adduct ( 27) formed in low yield (2.5%), resulted from hydrogen abstraction, i.e. the dienes (CF 3) 2NOCH(CHCH 2) 2 ( 24) (26.5%) and (CF 3) 2NOCH 2CHCHCHCH 2 ( 26) (19%) and the alkenes trans- and cis-(CF 3) 2NOCH 2CH[ON(CF 3) 2]CHCHCH 2ON(CF 3) 2 ( 25a) (44.5%) and ( 25) (5%), respectively. The gas-phase reaction between the oxadiazapentane 3 and diene 7 (1:1 molar ratio, ca. 20 °C) afforded a high yield of the 1:1 adduct ( 33) (70%), while a reaction carried out mainly in the liquid phase gave as major products compound 33 (36%) and a mixture of two 1:2 adducts considered to be diastereomers of the cyclopentane derivative CH 2=CHCH 2 CHCH[CH 2ON(CF 3) 2]CH 2CH[CH 2N(CF 3) 2] CH 2 ( 34) (41%). From the reaction of the oxyl 1 with allylbenzene ( 8) (2.5:1 molar ratio, −196 to ca. 20 °C) only products formed via hydrogen abstraction were isolated, i.e. the compounds (CF 3) 2NOCHPhCH[ON(CF 3) 2]CH 2ON(CF 3) 2 ( 28) as two diastereomers (20.5% and 10%), (CF 3) 2NOCHPhCHCH 2 ( 29) (37%) and (CF 3) 2NOCH 2CHCHPh ( 30) (16.5%). In contrast to this, the corresponding reaction involving the oxadiazapentane 3 (1:1 molar ratio, ca. 20 °C) gave the 1:1 adduct ( 35) (66.5%) and only a low yield (5.5%) of the hydrogen abstraction product 30.