Synthesis and Crystal Structure of Benzoyloxymethyl (4α,8β,13β)-13-methyl-16-oxo-17-norkauran-18-carbonate Ester

Isosteviol derivative: benzoyloxymethyl (4 alpha,8 beta,13 beta)-13-methyl-16-oxo-17-norkauran-18-carbonate ester was synthesized by esterification of isosteviol with chloromethyl benzoate and its crystal structure was determined by X-ray diffraction method. The compound crystallizes in the triclinic space group P1 with unit cell parameters: a = 8.784(3) angstrom, b = 9.079(3) angstrom, c = 15.950(6) angstrom, alpha = 79.343(6)degrees, beta = 79.061(5)degrees, gamma = 89.849(5)degrees, Z= 2. The conformation of rings A and B is chair, whereas the conformation of ring C is unsymmetrical twist chair. The carbonyl group at the C20 is coplanar with the benzene ring. The fragment of the ester group occupying the pseudoaxial site of C1 position adopts a zigzag conformation.