| abstract |
A process has been developed for production of taxols A, B, C with high yields from 7-xylosyl-10-deacetyl taxol A (taxol analogue A or, xyloside A), 7-xylosyl-10-deacetyl-taxol B (taxol analogue B or xyloside B), 7-xylosyl-10-deacetyl-taxol C (taxol analogue C or xyloside C), which comprises (i) isolating the taxol analogues A, B, C form the stembark of Taxus wallichiana by an improved process devoiding of solvent partitioning step, (ii) treating the isolated taxol analogues A, B, C with periodates in an acid free polar solvent medium to cleave the diol into dialdehyde at ambient temperature, (iii) reducing the dialdehyde solution with borohydride in a polar solvent-acetic acid medium at 0 DEG -40 DEG C. into an acetal, (iv) acidifying the resultant acetal with a mixture of mineral acid-polar solvent at 0 DEG -40 DEG C. into intermediate product 10-deacetyl taxols A, B, C, (V) reacting 10-deacetyl taxols A or B or C with a silane in presence of a base at 20 DEG -40 DEG C. to protect 2', 7-hydroxyl groups, of 10-deacetyl taxols A, B, C (vi) acetylating the 10-hydroxyl group in situ with an acetylating agent at 10 DEG -40 DEG C., (vii) deprotecting the 2', 7-hydroxyl groups with a mixture of mineral acid-polar solvent at 0 DEG -10 DEG C. (viii) isolating taxols A or B or C by chromatography over silica. |