Fiduxosin (1) has been under development at Abbott Laboratories for the treatment of benign prostatic hyperplasia. A convergent strategy required methodologies for preparation of an enantiomerically pure 3,4-cis-disubstituted pyrrolidine and a 2,3,5-trisubstituted thienopyrazine in a regiospecific manner. A [3+2] cycloaddition of an enantiopure azomethine ylide followed by a diastereoselective crystallization was employed to prepare the benzopyranopyrrolidine in high diastereomeric and enantiomeric purity. Conditions for reduction of an O-aryl lactone susceptible to epimerization were developed, and cyclization of the alcohol/phenol to the ether was accomplished in high yield. The thienopyrazine was prepared by condensation of methyl thioglycolate and a regiospecifically prepared 2-bromo-3-cyano-5-phenylpyrazine. Conditions for effective halogen substitutive deamination to prepare regiospecific trisubstituted pyrazines will be described.

中文翻译：

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Fiduxosin 的可扩展合成

雅培实验室正在开发 Fiduxosin (1)，用于治疗良性前列腺增生。收敛策略需要以区域特异性方式制备对映体纯的 3,4-顺-二取代吡咯烷和 2,3,5-三取代噻吩并吡嗪的方法。采用对映体纯偶氮甲碱叶立德的 [3+2] 环加成，然后进行非对映体选择性结晶，以制备高非对映体和对映体纯度的苯并吡咯吡咯烷。开发了易于差向异构化的 O-芳基内酯的还原条件，并以高产率完成了醇/苯酚到醚的环化。噻吩并吡嗪是通过缩合巯基乙酸甲酯和区域特异性制备的 2-溴-3-氰基-5-苯基吡嗪来制备的。