The chiral oxiranecarboxylic acids or esters 2a-e were obtained with lipase (CCL) in aqueous-organic system.The ee and the absolute configurations of the produc
By means of improved overlapping Muffin-Tin X_a method recently developed theground state ~2(?)and the first excited state ~2Σ~+ of the XBS~+(X=H,F,Cl)cations
A series of di-n-hexyl alkyl phosphonates with bulky substituent on phosphorus was synthesized by PTC P-alkylation using crown ether.Upon saponification of the
The structure of a new macrocyclic compound, clemochinenoside A obtained from Clematis chinensis was identified by NMR, FAB-MS, NOE and chemical hydrolysis.
25-Hydroxycholesterol, which is an important intermediatefor the synthesis of 25-hvdroxyvitamin D<sub>3</sub> and 1α, 25-dihydroxyvitamin D<sub>3</sub>,was pre