Abstract16β‐Methylcorticoids are among the most important glucocorticoid steroids for the treatment of various dermatological disorders, respiratory infections, and other allergic reactions elicited during inflammatory responses of the human body. Betamethasone dipropionate, clobetasol propionate, and beclomethasone dipropionate are particularly noteworthy for their synthetic intractability. Despite five decades of research, these 16β‐methylcorticoids have remained challenging synthetic targets owing to insurmountable issues of reactivity, selectivity, and cost efficiency associated with all previously explored strategies. We herein report our practicability‐oriented strategy toward the unified stereoselective synthesis of 16β‐methylcorticoids in 12.6–14.0 % overall yield from commercially available 9α‐hydroxyandrost‐4‐ene‐3,17‐dione (9α‐OH‐AD). In this approach, the chiral C16β‐Me and C17α‐OH groups of the corticosteroid D ring were installed via a substrate‐controlled diastereo‐ and enantioselective Mn‐catalyzed oxidation‐reduction hydration of Δ4,9(11),16‐triene‐3,20‐dione. The C1−C2 double bond of the corticosteroid A ring was constructed using an unprecedented engineered 3‐ketosteroid‐Δ1‐dehydrogenase (MK4‐KstD)‐catalyzed regioselective Δ1‐dehydrogenation of Δ4,9(11)‐diene‐3,21‐dione. This strategy provides a general method and a key precursor for the divergent synthesis of a variety of glucocorticoids and related steroidal drugs.
摘要16β-甲基皮质激素是治疗各种皮肤病、呼吸道感染和人体炎症反应期间引起的其他过敏反应的最重要的糖皮质激素之一。倍他米松二丙酸酯、氯倍他索丙酸酯和倍氯米松二丙酸酯因其难合成性而特别值得注意。尽管经过了五十年的研究,这些 16β - 甲基皮质激素仍然是具有挑战性的合成目标,原因是与之前探索的所有策略相关的反应性、选择性和成本效益等问题难以克服。我们在此报告我们以实用性为导向的策略,利用市售的 9α-hydroxyandrost-4-ene-3,17-dione (9α-OH-AD),以 12.6-14.0 % 的总收率统一立体选择性合成 16β-甲基皮质激素。在这种方法中,通过底物控制的非对映和对映选择性锰催化Δ4,9(11),16-三烯-3,20-二酮的氧化-还原水合反应,皮质类固醇 D 环上的手性 C16β-Me 和 C17α-OH 基团得以形成。皮质类固醇 A 环的 C1-C2 双键是利用一种前所未有的工程化 3-酮类固醇-Δ1-脱氢酶(MK4-KstD)催化的 Δ4,9(11)-二烯-3,21-二酮的区域选择性Δ1-脱氢反应构建的。这一策略为多种糖皮质激素和相关甾体药物的多元合成提供了通用方法和关键前体。