CC-1065 analog synthesis
Improved synthesis of seco(−)CBI (5-hydroxy-3-amino-1-[S]-(chloromethyl)-1,2-dihydro-3H-benz(e)indole): and improved syntheses therefrom of a wide variety of CC-1065 analogs that comprise a cyclopropabenzidole (CBI) alkylating moiety, and which are collectively DC1 and its derivatives, for the synthesis of cell-targeted therapeutic agents.
1. A process for preparing a compound of the formula A-B-C, wherein the formula (I), as hereinafter defined represents the group AH and B-C represents a compound selected from the group consisting of formulae (V)-(VIII) as hereinafter defined, said process comprising:
(a) preparing a compound of formula (I)
comprising:
(i) providing a compound of formula (II), wherein R is a protecting group,
(ii) performing halogenation, alkylation and ring-closure reactions upon a compound of formula (II) under suitable conditions to provide a racemic compound of formula (III),
(iii) isolating the (−) isomer of the racemic compound of formula (III), and
(iv) removing said R protecting groups from the isolated (−) isomer of the racemic compound of formula (III) under suitable conditions to produce a compound of formula (I), and
(b) linking, via an amide bond, group A, with one compound selected from the group consisting of formulae (V)-(VIII), or linking, via an amide bond, group A, with B of B-C, prior to linking the group B to the group C:
wherein R 1 to R 6 may be the same or different and are selected from the group consisting of hydrogen, C 1 -C 3 linear alkyl, methoxy, hydroxyl, primary amino, secondary amino, tertiary amino, and amido, and
wherein R″ is an amine or substituted or unsubstituted C 1 -C 20 alkyl amine.
2. The process of claim 1 , wherein R″ in formulae (V)-(VIII) forms an amide bond with the carboxyl group of HOOC—R 7 —S—R 8, wherein R 7 is a linker and R 8 is a thiolate leaving group that is capable of undergoing a disulfide exchange reaction.
3. The process of claim 2 , wherein the linker is a substituted or unsubstituted C 1 -C 20 alkyl group or a polyethylene glycol spacer.
4. The process of claim 2 , wherein the thiolate leaving group is —SCH 3 , thiopyridyl, —S-alkyl, —S-aryl, glutathione or cysteine.
5. The process of claim 1 , wherein said amide bond is formed using EDC.
6. The process of claim 1 , wherein the compound of formula VIII is compound VIIIa
and the process further comprises formation of an amide bond between the phenyl amine of compound VIIIa and the carboxyl of HOOC—R 7 —S—R 8 , wherein R 7 is ethyl and R 8 is —S-alkyl or —S-aryl to yield a compound of formula (IV)
7. The process of claim 6 , wherein R 1 is —SS—CH 3 or —SS-pyridyl.