Method for preparing camptothecin derivatives

A compound of Formulas (IV) or (VI):

• wherein:
• X is halo;
• R1 and R2, which may be the same or different, are independently selected from hydrogen, lower alkyl, (C3-7) cycloalkyl, (C3-7)cycloalkyl lower alkyl, lower alkenyl, hydroxy lower alkyl, or alkoxy alkyl, or (—CH2NR7R8), wherein:
• i) R7 and R8, which may be the same or different, are independently selected from hydrogen, lower alkyl, (C3-7) cycloalkyl, (C3-7) cycloalkyl lower alkyl, lower alkenyl, hydroxy lower alkyl, or lower alkoxy lower alkyl;
• or
• ii) R7 represents hydrogen, lower alkyl, (C3-7)cycloalkyl, (C3-7) cycloalkyl lower alkyl, lower alkenyl, hydroxy lower alkyl, or lower alkoxy lower alkyl, and R8 represents —COR9,
• wherein:
• R9 represents hydrogen, lower alkyl, perhalo-lower alkyl, (C3-7)cycloalkyl, (C3-7) cycloalkyl lower alkyl, lower alkenyl, hydroxy lower alkyl, lower alkoxy, lower alkoxy lower alkyl;
• or
• iii) R7 represents hydrogen or lower alkyl;
• and R8 represents diphenyl-methyl or —(CH2)tAr
• wherein:
• t is 0 to 5 and Ar represents phenyl, furyl, pyridyl, N-methylpyrrolyl, imidazolyl optionally substituted with one or more substituents selected from hydroxy, methyl, halogen, and amino;
• or
• iv) R7 and R8 taken together with the linking nitrogen form a saturated 3 to 7 atom heterocyclic group of formula (IA)
• wherein:
• Y represents O, S, SO, SO2, CH2 or NR10,
• wherein:
• R10 represents hydrogen, lower alkyl, perhalo lower alkyl, aryl, aryl substituted with one or more substituents selected from lower alkyl, lower alkoxy, halogen, nitro, amino, lower alkyl amino, perhalo-lower alkyl, hydroxy lower alkyl, lower alkoxy lower alkyl groups or —COR11,
• wherein:
• R11 represents hydrogen, lower alkyl, perhalo-lower alkyl, lower alkoxy, aryl, aryl substituted with one or more substituents selected from lower alkyl, perhalo-lower alkyl, hydroxy lower alkyl, lower alkoxy lower alkyl groups;
• and
• R3 and R4 are independently selected from hydrogen, lower alkyl, (C3-7)cycloalkyl, (C3-7)cycloalkyl lower alkyl, lower alkenyl, hydroxy lower alkyl, or alkoxy alkyl;
• or
• R3 and R4 taken together form a saturated 5 to 6 atom heterocyclic group of formula (IB)
• wherein,
• n represents the integer 1 or 2;
• and
• R5 represents hydrogen or lower alkyl, and
• R6 represents hydrogen or lower alkyl, or
• pharmaceutically acceptable salts thereof.