Oxa-Michael-based divergent synthesis of artificial glutamate analogs.

Herein we report stereoselective generation of two skeletons, 1,3-dioxane and tetrahydropyranol, by oxa-Michael reaction as the key reaction from δ-hydroxyenone. The construction of the 1,3-dioxane skeleton, achieved through hemiacetal formation followed by oxa-Michael reaction from δ-hydroxyenone, was exploited to access structurally diverse heterotricyclic artificial glutamate analogs. On the other hand, formation of a novel tetrahydro-2-pyranol skeleton was accomplished by the inverse reaction order: oxa-Michael reaction followed by hemiacetal formation.

Nuclear quantum effect and H/D isotope effect on Cl· + (HO) → HCl + OH·(HO) ( = 1-3) reactions.

Cl· + (HO) → HCl + OH·(HO) ( = 1-3) reactions are fundamental and important ones in atmospheric chemistry. In this study, we focused on the nuclear quantum effect (NQE) of the hydrogen nucleus on these reactions with the aid of the multicomponent quantum mechanics (MC_QM) method, which can directly take account of NQE of light nuclei. Our study reveals that the NQE of the hydrogen nucleus lowers the activation barriers of the reactions and enhances the catalytic effects of second and third water molecules.

Reaction mechanism of hydrogen-tritium exchange reactions between several organic and HTO molecules: a role of the second HTO.

The mechanism of hydrogen-tritium (H-T) exchange reactions between several small organic and HTO molecules have been investigated using M06-2X/6-311++G(d,p) method. The second HTO molecule is taken into account for both direct and addition-elimination H-T exchange reactions. The reactivity of small organic molecules for H-T exchange reactions is in the order of CHCOOH > CHCHOH > CHCHO ≈ CHCOCH ≈ CH and CH > CH, CH, and CH.