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