283173-50-2

Rucaparib is a poly (ADP ribose) polymerase (PARP) inhibitor. PARP is a DNA damage-activated nuclear enzyme that has a key signaling role in the base excision repair pathway.

ChEBI: Rucaparib is a member of the class of azepinoindoles that is 1,3,4,5-tetrahydro-6H-azepino[5,4,3-cd]indol-6-one carrying additional 4-[(methylamino)methyl]phenyl and fluoro substituents at positions 2 and 8 respectively. It is an inhibitor of poly (ADP-ribose) polymerase and is used (as the camsylate salt) as monotherapy for advanced ovarian cancer and deleterious germline or somatic BRCA mutation. It has a role as an EC 2.4.2.30 (NAD(+) ADP-ribosyltransferase) inhibitor and an antineoplastic agent. It is an azepinoindole, a member of caprolactams, an organofluorine compound and a secondary amino compound. It is a conjugate base of a rucaparib(1+).

Synthesis of rucaparib camsylate begins from commercially available phthalimide acetal 151. Unveiling of the aldehyde via treatment with aqueous HCl and precipitation from toluene provided aldehyde 152 in 62% yield. To avoid polymerization, 152 was immediately subjected to 6-fluoro-1Hindole- 4-carboxylic acid methyl ester (153) under reductive conditions in the presence of acid to give rise to tryptamine derivative 154. After considerable research, optimal conditions for this transformation (triethylsilane in DCM/TFA) were found that were successful on up to 15.7 kg scale, enabling clean separation of the aldehyde reduction byproduct following crystallization. Conversion of the phthalimide within 154 to the corresponding amine using aqueous methylamine at room temperature was accompanied by an intramolecular cyclization reaction to secure the intermediate lactam as a solid in 89% isolated yield. This was followed by a high-yielding bromination reaction (83%) at the indole C-2 position employing pyridinium tribromide, providing access to indoloazepinone 155. After screening various catalysts for the coupling of bromide 155 and commercial boronic acid 156, Pd(dppf)Cl2?¤ DCM was found to reliably deliver the desired coupling product with reasonable rates of reaction. Thus, after development of an extensively optimized reaction protocol, Suzuki coupling of 155 and 4-formylphenylboronic acid (156) with Pd(dppf)Cl2?¤DCM and Na2CO3 in DMA at 90 ??C generated the desired 2-arylated indole 157 in high yield (92%) after trituration and reslurry with methanol. Conversion of aldehyde 157 to amine 158 necessitated a two-pot procedure designed to limit the formation of dimerization and aldehyde reduction products that generally arise under conventional onepot reductive amination conditions and have traditionally been problematic on scale. Toward this end, subjection of aldehyde 157 to a methylamine solution in EtOH/MeOH/THF and wash of the resulting reaction solids with methanol led to efficient isolation of pure imine intermediate, which could be immediately reduced with NaBH4 in THF/MeOH, providing hydrochloride salt 158 upon acidic workup in 76% over two steps. The two remaining steps for conversion to the drug involve a salt-swap, first breaking the HCl salt with NaOH in MeOH, then treatment with (S)-camphorsulfonic acid/IPA/ H2O at 70 ??C. Filtration and washing of the cake with water generated rucaparib camsylate (XVII) in 95% yield.