Journal of the American Chemical Society p. 5894 - 5902 (1981)
Update date:2022-08-05
Topics:
Rowell, Robert
Gorenstein, David G.
The epimeric 2-(aryloxy)-2-oxo-trans-5,6-tetramethylene-1,3,2-dioxaphosphorinanes 1-4 (ArO = p-methoxyphenoxy, p-nitrophenoxy, phenoxy, and 2,4-dinitrophenoxy) and isomeric 2-(p-nitrophenoxy)-2-oxo-trans-5,6-tetramethylene-1,3,2-oxazaphosphorinane (5) were hydrolyzed in 30percent dioxane/water at 70 deg C with a variety of nucleophiles.The reactivities were sensitive to changes in both the nucleophile and leaving group.The Broensted βnuc's for the equatorial leaving groups 2,4-DNP, PNP, and Ph are 0.48, 0.64, and 0.75, respectively.The Broensted βlg's are -0.96, -1.04, -0.85, -0.66, -0.64, -0.57, -0.46, and -0.35 for nucleophiles water, methoxyacetate, acetate, phosphate, hexafluoroisopropoxide, carbonate, trifluoroethoxide, and hydroxide, respectively, for the equatorial triesters.These results are best interpreted in terms of a change in mechanism from a concerted SN2(P) process to a stepwise one.The stepwise mechanism via a pentacovalent intermediate is supported by the stereochemistry of reaction and epimeric rate ratios.Thus, some retention of configuration at phosphorus was observed in the methanolysis of all triesters except 4b and 5b.Also the hydroxide-catalyzed hydrolysis of 4a and 1b yielded some retention at phosphorus, and, therefore, a pentacovalent intermediate is required for attack by very basic nucleophiles.This agrees with the kinetic results if one considers the fact that βlg for hydroxide is only 0.35.Solvent deuterium isotope effects, kH2O/kD2O, for acetate-catalyzed hydrolysis of the dinitrophenyl triesters were determined to be 1.08.Thus, these triesters hydrolyze mostly via nucleophilic catalysis.The isotope effects for phosphate-catalyzed hydrolysis of the equatorial p-nitrophenyl and phenyl triesters are 1.19 and 1.8, respectively.This indicates an increasing amount of hydrolysis via general-base catalysis toward the poorer leaving groups.
View MoreShanghai Massive Chemical Technology Co., Ltd.
website:http://www.massivechem.com/
Contact:+86 21 34943721
Address:Room 435, 4th floor, Building 9, No. 2568 Gudai Road,Minhang District, Shanghai,
SHUNYUANSHENG BIO-PHARMTECH CO., LTD
website:https://www.whsysbio.com
Contact:--
Address:Building 13, Liandong U Valley-Wuhan Economic Innovation Valley, No. 259, Xingsan Road, Shamao Street, Hannan District, Wuhan City, Hubei Province
Beijing Zhongshuo Pharmaceutical T & D Co.,Ltd
Contact:0086-10-64430626
Address:ea No 16, HEPINGLI,DONGCHENG DISTRICT,BEIJING,P.R.CHINA.
Huangshan Violet Biological Technology Co., Ltd
Contact:+86-559-2335676
Address:16-201 JinShanYuan,JiangNan New City,TunXi District,HuangShan City,AnHui Province,China
Shaanxi HuaTai Bio-fine chemical company Ltd
Contact:86-029-87862197
Address:No. 5, 3rd Floor, 29 Yanta North Road, Beilin Dist.
Doi:10.1021/jacs.7b03296
(2017)Doi:10.1016/0022-328X(85)80095-4
(1985)Doi:10.1016/S0022-1139(00)82577-4
(1980)Doi:10.1002/hlca.19800630213
(1980)Doi:10.1016/S0022-328X(00)81794-5
(1980)Doi:10.1021/ja01105a016
(1953)