Stereochemical Course of Cerium(IV)-Catalyzed Hydrolysis of Cyclic Nucleotides
摘要:
Ce-IV has been shown to catalyze the hydrolysis of thymidine 3',5'-cyclic thiophosphate (cTMPS) to give a mixture of 3'-TMPS and 5'-TMPS with rates comparable to those previously reported for cAMP and cTMP. The ratio of the 3'-TMPS and 5'-TMPS products was dependent on the absolute configuration of the cTMPS; starting from Rp cTMPS, with the sulfur equatorial, the 3'-TMPS:5'-TMPS ratio was ca. 7:1 whereas for the corresponding S-p cTMPS the ratio was 3:2. Both diastereoisomers of thymidine 3',5'-cyclic [O-18]-thiophosphate have been synthesized, and the stereochemical course of the hydrolysis reaction catalyzed by Ce-IV has been determined. In each case, the reaction proceeds with clean inversion of configuration, consistent; with coordination of the metal ion to the exocyclic oxygen substituent and delivery of the hydroxide nucleophile from one of the remaining metal coordination sites with in-line geometry.
The microwave spectrum of oxygen-18-labeled phosphoryl chloride: Refinement of the harmonic force field and the molecular structure
作者:Steven Firth、R.Wellington Davis
DOI:10.1016/0022-2852(88)90020-3
日期:1988.1
been combined with those of earlier microwave and vibrational studies to obtain an improved harmonicforcefield for phosphoryl chloride. The results of the present investigation have made it possible to determine for the first time a precise spectroscopic geometry for the OPCl3 molecule. Ground state effective, ground state average, and an approximate equilibrium geometry have been calculated. The