Patent ID: 7429658

Claim:
A method of synthesis of a compound of formula (I): comprising the steps of: (a) reacting a compound of formula (II) with a compound of formula (III) to yield a compound of formula (IV): (b) converting the compound of formula (IV) to a compound of formula (I): wherein the dotted lines indicate the optional presence of a double bond between C1 and C2 or C2 and C3; R 2 and R 3 are independently selected from —H, —OH, ═O, ═CH 2 , —CN, —R, OR, ═CH—R, O—SO 2 —R, CO 2 R and COR; R 6 , R 7 and R 9 are independently H, R, OH, OR, SH, SR, NH 2 , NHR, NRR′, nitro, Me 3 Sn and halo; R 8 is either selected from H, R, OH, OR, SH, SR, NH2, NHR, NRR′, nitro, Me 3 Sn and halo or the compound is a dimer with each monomer being the same of different and being of the relevant formula, where the R 8 groups of each monomer form together a bridge having the formula —X—R″—X—, where R″ is a C 3−12 alkylene group, which chain may be interrupted by one or more heteroatoms and/or aromatic rings, and each X is independently selected from O, S and NH; R 10 is such that R 10 —OC(═O)— forms a nitrogen protecting group; R 11 is either H or R; R 12 is an optionally substituted C 1−4 alkyl group; P and Q are such that —CPQ is a masked aldehyde group; wherein R and R′ are independently selected from optionally substituted C 1−20 alkyl, C 3−20 heterocyclyl, and C 5−20 aryl; wherein T is O or S, and each R ac , is independently selected from C 1−10 alkyl or together can be a C 1−3 alkylene group.