Theoretical study of O2-H2O: potential energy surface, molecular vibrations, and equilibrium constant at atmospheric temperatures.

The intermolecular potential energy surface of O(2)-H(2)O was investigated at ab initio MP2 and MRSDCI levels using the aug-cc-pVTZ basis set. The vibrational levels were evaluated by numerically solving the Schrödinger equations for the nuclear motions with the ab initio potential functions using one- to three-dimensional finite-element methods. On the basis of the calculated partition functions, the equilibrium constant of the complex, K(p), was studied. The K(p) values at atmospheric temperatures of 200-300 K were found to be 1-2 orders of magnitude less than previous estimates from the harmonic oscillator approximation.

First asymmetric total synthesis of Us-7 and -8, novel D-seco Corynanthe-type oxindole alkaloids from Uncaria attenuata: structure revision of Us-7 and determination of absolute stereochemistry.

[reaction: see text] Starting from (S)-glycidol, the asymmetric total synthesis of novel D-seco Corynanthe-type oxindoles Us-7 and Us-8 was accomplished. The structure of Us-7 was revised from the reported structure 1 with the (3R,7S) form to structure 22 with (3S,7R), and the absolute stereochemistry at C15 of both alkaloids was established.