Journal of the American Chemical Society p. 6749 - 6757 (1989)
Update date:2022-08-04
Topics:
Mello, Rossella
Fiorentino, Michele
Fusco, Caterina
Curci, Ruggero
The reaction of methyl(trifluoromethyl)dioxirane (1b), a novel dioxirane species, with two open-chain, four cyclic, and five polycyclic saturated hydrocarbons and two aralkyl hydrocarbons in CH2Cl2/1,1,1-trifluoropropanone has been studied; under mild conditions (-22 to 0 deg C), it gives alcohols and/or ketones (deriving from further oxidation of secondary alcohols) in high yields and within very short reaction times.Primary C-H bonds are not appreciably oxidized and high regioselectivities were determined for attack at tertiary over secondary C-H bonds, with theexception of norbornane, which showed opposite regioselectivity.The reaction is also highly stereoselective, since hydroxylations of cis- and trans-decalin and of cis- and trans-1,2-dimethylcyclohexane were found to be in each case stereospecific with retention.From kinetic data, Ea = 14.3 kcal mol-1 and log A = 9.9 were estimated for cyclohexane oxidation.Relative rates change in the order cyclohexane (0.78) < norbornane (1) < bicyclo<2.2.2>octane (9.2) < adamantane (146); cis-1,2-dimethylcyclohexane was observed to be 7-fold more reactive than its trans isomer, demonstrating remarkable discrimination for equatorial vs axial C-H attack (also noticed in the case of cis- and trans-decalin).The relative rate of oxidation of cumene vs ethylbenzene was found to be ca. 3.1 (after statistical correction), i.e., in sharp excess over values usually recorded in classical radical H-atom abstraction from benzylic position.Rate constants determined for the reactions of cumene and of ethylbenzene show the title dioxirane (1b) is more reactive than dimethyldioxirane (1a) by factors of ca. 600 and over 700, respectively.The whole of theobservations is better accommodated by an "oxenoid" mechanism, involving concerted O-atom insertion by dioxirane into C-H bonds of hydrocarbons.
View Morewebsite:http://www.easchem.com
Contact:+86-731-89722861 89722891
Address:2/F-4/Bld Colorful Palace, No.605 Changsha Ave, Yuhua Area Changsha Hunan China.
Shijiazhuang Yunxuan Im&Export Co.,Ltd.
Contact:+86-311-83037514
Address:No.6 Hongbin Road
TAIZHOU XINGCHENG CHEMPHARM CO.,LTD.
Contact:0086-0576-88551200,88886292 ,88880039
Address:B Area. 10 Floor.Yaodadasha. 289#.Shifu Road.Taizhou.Zhejiang.China
Contact:86-21-68404353-215
Address:Rm 710, 30 BLDG, 2419 Hu Nan RD., Pudong New Area, Shanghai, China
Jiangxi Hito Chemical Co., Ltd.
Contact:+86-792-3170318
Address:No. 6, Tianhong Ave., Xinghuo Industry Park, Yongxiu, Jiujiang, Jiangxi, China
Doi:10.1002/jlac.197519750607
(1975)Doi:10.1002/hlca.19750580322
(1975)Doi:10.1021/jm00370a008
(1984)Doi:10.1055/s-2003-38364
(2003)Doi:10.1016/0040-4020(75)87025-6
(1975)Doi:10.1021/ja00408a017
(1981)