Sutar Revannath L, Sen Saumik, Eivgi Or, Segalovich Gal, Schapiro Igor, Reany Ofer, Lemcoff N Gabriel
Department of Chemistry , Ben-Gurion University of the Negev , Beer-Sheva 84105 , Israel . Email:
Department of Natural Sciences , The Open University of Israel , Ra'anana , 43537 , Israel.
Chem Sci. 2017 Dec 18;9(5):1368-1374. doi: 10.1039/c7sc05094a. eCollection 2018 Feb 7.
Allylic and acrylic substrates may be efficiently transformed by a sequential bichromatic photochemical process into derivatives of levulinates or butenolides with high selectivity when phenanthrene is used as a regulator. Thus, UV-A photoinduced cross-metathesis (CM) couples the acrylic and allylic counterparts and subsequent UV-C irradiation initiates - isomerization of the carbon-carbon double bond, followed by one of two competing processes; namely, cyclization by transesterification or a 1,5-H shift and tautomerization. Quantum chemical calculations demonstrate that intermediates are strongly blue-shifted for the cyclization while red-shifted for the 1,5-H shift reaction. Hence, delaying the double bond migration by employing UV-C absorbing phenanthrene, results in a selective novel divergent all-photochemical pathway for the synthesis of fundamental structural motifs of ubiquitous natural products.
当使用菲作为调节剂时，烯丙基和丙烯酸酯底物可通过连续双色光化学过程高效地转化为具有高选择性的乙酰丙酸酯或丁烯内酯衍生物。因此，UV-A光诱导交叉复分解（CM）使丙烯酸酯和烯丙基对应物偶联，随后的UV-C照射引发碳-碳双键的异构化，接着是两个竞争过程之一；即通过酯交换进行环化或1,5-H迁移和互变异构。量子化学计算表明，中间体对于环化反应强烈蓝移，而对于1,5-H迁移反应则红移。因此，通过使用吸收UV-C的菲来延迟双键迁移，可产生一种选择性的新型全光化学途径，用于合成普遍存在的天然产物的基本结构基序。
