A convenient synthesis of the immunosuppressive agent FTY720

Synthesis, characterization and control of eight process related and two genotoxic fingolimod impurities by a validated RP-UPLC method

An HPLC method has been described in European and United States Pharmacopoeias (Ph. Eur. and USP) for determination of nine organic impurities (imp A-I) in fingolimod hydrochloride, a synthetic sphingosine-1-phosphate receptor modulator. The manufacturing process of fingolimod hydrochloride consists of multi-step chemical synthesis wherein controls of precursors, intermediates and process steps should be done to assure the final quality of drug substance. We synthesized and isolated eight process related impurities (FINI imp A-H) of fingolimod, different than the pharmacopoeial impurities. One unknown process-related impurity was found in key-intermediate (FINI) and was identified by LC-MS. Characterization of all impurities were done by using spectroscopic techniques (¹ H & ¹³ C NMR, FTIR, MS), and the mechanistic pathways to the formation of these impurities were also discussed. Two of these impurities were evaluated as potential genotoxic impurities due to their alerting structures and alkylating properties (alkyl sulfonates and alkyl halides, class 3, ICH M7). We also developed and validated a RP-UPLC method in line with ICH Q2 guidelines for control these impurities (FINI imp A-H) and to assure the pharmacopoeial quality drug substance.

Organic synthesis with the most abundant transition metal–iron: from rust to multitasking catalysts

The promising aspects of iron in synthetic chemistry are being explored for three-four decades as a green and eco-friendly alternative to late transition metals. This present review unveils these rich iron-chemistry towards different transformations.

Total Synthesis of Mallotusinin

The total synthesis of mallotusinin, which bears a tetrahydroxydibenzofuranoyl (THDBF) bridge between the 2-oxygen and 4-oxygen of glucose on corilagin with a 3,6-O-(R)-hexahydroxydiphenoyl (HHDP) bridge, is described. The key features of the total synthesis are: 1) improvements of our previously reported method to synthesize corilagin; 2) establishment of the THDBF skeleton via an unusual intramolecular S_N Ar reaction of an HHDP analogue, and 3) the application of a two-step bislactonization strategy for a HHDP bridge construction into the 2,4-O-THDBF bridge. Oxidative phenol coupling of 1,2,4-orthoacetyl-3,6-di-(4-O-benzylgalloyl)-α-d-glucopyranose and the orthoester cleavage of the coupling product without the pyranose-furanose ring transformation are key reactions for the improved synthesis of corilagin, which enabled the adequate supply of a corilagin precursor that was required to develop the mallotusinin synthesis. These established methods are expected to help develop the synthesis of other ellagitannins with a bridge between the two oxygens of corilagin.

Iron-Catalyzed C-C Cross-Couplings Using Organometallics

Over the last decades, iron-catalyzed cross-couplings have emerged as an important tool for the formation of C-C bonds. A wide variety of alkenyl, aryl, and alkyl (pseudo)halides have been coupled to organometallic reagents, the most currently used being Grignard reagents. Particular attention has been devoted to the development of iron catalysts for the functionalization of alkyl halides that are generally challenging substrates in classical cross-couplings. The high functional group tolerance of iron-catalyzed cross-couplings has encouraged organic chemists to use them in the synthesis of bioactive compounds. Even if some points remain obscure, numerous studies have been carried out to investigate the mechanism of iron-catalyzed cross-coupling and several hypotheses have been proposed.