| 摘要 |
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 preferably comprises (i) isolating the taxol analogues A,B,C from the stembark of Taxus wallichiana by an improved process devoid of a 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 0-40 DEG C into an acetal, (iv) acidifying the resultant acetal with a mixture of mineral acid-polar solvent at 0-40 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 20-40 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 10-40 DEG C, (vii) deprotecting the 2', 7-hydroxyl groups with a mixture of mineral acid-polar solvent at 0-10 DEG C (viii) isolating taxols A or B or C by chromatography over silica. |
