Journal of the Chemical Society. Perkin transactions II p. 890 - 899 (1980)
Update date:2022-08-05
Topics:
Busby, Reginald E.
Dominey, Terence W.
The rates of rearrangement of the series 5-methyl, 5-ethyl, 5-isopropyl-, and 5-t-butyl-2-amino-1,3,4-thiadiazines in strong acid have been followed by observing the u.v. absorptions of the protonated thiadiazine substrates or the product thiazolimines.The rates of rearrangement were found to be first order with respect to the thiadiazine concentration and the rates decreased along the series in a manner characteristic of an SN2 reaction.The rates of rearrangement of 2-amino-1,3,4-thiadiazines with phenyl, p-nitrophenyl, and p-hydroxyphenyl groups in the 5-position were all extremely slow whereas 2-amino-5-benzyl-1,3,4-thiadiazine rearranged much faster than these arylthiadiazines but more slowly than the 5-methyl and 5-ethyl compounds.The rearrangement rates of 2-amino-5-methyl-1,3,4-thiadiazine were followed at various acid strengths within the range 4.47-8.12M-HCl.The reaction ultimately reached equilibrium, and the measured constant, k1, was equal to the sum of the velocity constants (kr + k-r) of the forward and backward reactions.Both kr and k-r were found to be similarly dependent on acidity and water activity.Using H0 values derived by Long and Paul with substituted anilines, a plot of log10k1 against -H0 was found to be linear and of slope equal to 0.92.A slope of -5.4 (w*) was obtained from the Bunnett plot of log10k1/CH(1+) against log10aw.A Yagil plot of log10k1/CH(1+) against log10Cw was linear and of slope equal to -2.95 at acidities less than 6.9M-HCl.Replacement of H by D at position 6 in all the thiadiazines was observed in D2O only in strong acid and D was incorporated both into the unchanged thiadiazaine and the product thiazolimine (at position 5).A mechanism is suggested for the rearrangement which involves transannular nucleophilic attack by N(3) at an sp3 carbon atom in the 5 position of the thiadiazines.
View MoreZhenjiang Haitong Chemical Industry Co., Ltd.
Contact:+86 (511) 8448-0369
Address:Baoyan Town, Dantu District, Zhenjiang City, Jiangsu, China
Nanjing Zelang Medical Technology Co. Ltd
Contact:86-25-83063290/13770714480
Address:Ganjiabian 108# 01 Unit,701-702 room,Yao Hua Street,Qixia District,Nanjing,Jiangsu,China
SHIJIAZHUANG CHENSHI IMPORT AND EXPORT CO.,LTD
Contact:+86-311-89871056
Address:RM2017 BUILDING CTIANSHAN GALAXY PLAZA,NO168 CHANGJIANG ROAD,GAOXIN DISTRICT,SHIJIAZHUANG CITY, HEBEI,CHINA
Tengzhou Runlong Fragrance Co., Ltd.
website:http://www.tzrunlong.com/
Contact:--
Address:No. 78, Fushan Road, Biomedical Industrial Park, Dawu Town, Tengzhou, Shandong, 277514 China
Jiangxi Province Bethel Pharmaceutical Co., Ltd.
Contact:+86-795-259 3456 ，+86-15957688008 13566650571
Address:Huangjindui Chemical Park， Shanggao County ，Yichun city，Jiangxi Province
Doi:10.1021/ja01204a007
(1947)Doi:10.1021/ja00533a011
(1980)Doi:10.1111/j.1751-0813.2000.tb11742.x
(1930)Doi:10.1016/S0040-4039(00)77740-9
(1980)Doi:10.1039/a708134k
(1998)Doi:10.1016/j.tetlet.2014.12.042
(2015)
