| abstract |
Prepn. of a substd. isoserine ester (I) comprises reacting a beta-lactam of (II) with a metal alkoxide MOCE1E2E3 (III). In the formulae, R1 = OR6, SR7, or NR8R9; R2 = H, 1-15C alkyl, 2-15C alkenyl, 2-15C alkynyl, 6-15C aryl, or heteroaryl (all opt. substd.); R3, R4 = as R2, or acyl, provided that R3 and R4 are not both acyl; R5 = COR10, COOR10, COSR10, CONR8R10, SO2R11, or POR12R13; R6 = as R2, OH protecting gp., or gp. to increase water solubility in a taxane deriv.; R7 = as R2 (but not H), or SH protecting gp.; R8 = as R2; R9 = amino protecting gp.; R10 = as R2 (but not H); R11-R13 = as R2 (but not H), OR10 or NR8R14; R14 = as R2; and E1-E3 = H, hydrocarbon, or cyclic; provided that at least one of E1-E3 is other than H. Prepn. of a taxane deriv. comprises the above process, in which one of E1-E3 = H and CE1E2E3 = a polycyclic skeleton, to form an intermediate; and converting this into the taxane deriv. |