Journal of Organic Chemistry p. 4345 - 4350 (1981)
Update date:2022-08-03
Topics:
McClelland, Robert A.
Somani, Riaz
Hydrolysis of the title oxazolidine, III, occurs in two separate reaction stages, reversible ring opening to a cationic Schiff base, IV, followed by a considerably slower formation of hydrolysis products.The ring opening occurs in an H+-catalyzed reaction and in a pH-independent reaction, with the crossover between the two occurring at about pH 5.A general acid catalyzed pathway (α = 0.70) is also observed.The equilibrium constant (pKI(+)) for IV * III + H+ is 7.45, this number being obtained spectroscopically and in a kinetic analysis.The kinetic analysis also furnishes a dissociation constant (pKSH(+)) for the protonated oxazolidine of 6.19, the difference between pKSH(+) and pKI(+) showing that after attainment of equilibrium the conjugate acid of III is a 19:1 mixture of cationic Schiff base and protonated oxazolidine.The formation of hydrolysis products involves rate-limiting addition of water or hydroxide ion to IV, although a small percentage of a reaction via an oxocarbonium ion derived from C-N cleavage of the protonated oxazolidine cannot be ruled out.Rate constants for the water and hydroxide addition are slower than their intramolecular counterparts, this being particulary true in comparing hydroxide ion reactions.This occurs despite the fact that the ring closure is a supposedly disfavored 5-endo-trigonal process.
View MoreContact:86-512-87182055
Address:No.128 Fangzhou Rd, Suzhou Industrial Park, China, 215125, China
Contact:13357117572
Address:No.149 Shiji dadao Road.
website:https://www.sinoshiny.com/products
Contact:+86-20-62802632;62802633
Address:Room 330 GIGCAS Building,No.511 Kehua Street,Tianhe District
Shenzhen Sunrising Industry Co., ltd.
Contact:+86 755 86571158 / 86571159 / 86571160
Address:2108 ZHENYE INT. BUSINESS CENTER,NO.3101-90 QIANHAI RD, NANSHAN,SHENZHEN, CHINA
Contact:+86-731-84427351
Address:154 JIANXIANG SOUTH ROAD
Doi:10.1002/adsc.201300846
(2013)Doi:10.1021/ja962736v
(1996)Doi:10.1021/jo00334a018
(1981)Doi:10.1007/BF00765592
(1981)Doi:10.1016/S0040-4039(01)90462-9
(1981)Doi:10.1016/S0022-1139(00)81440-2
(1982)