Guiding a divergent reaction by photochemical control: bichromatic selective access to levulinates and butenolides
作者:Revannath L. Sutar、Saumik Sen、Or Eivgi、Gal Segalovich、Igor Schapiro、Ofer Reany、N. Gabriel Lemcoff
DOI:10.1039/c7sc05094a
日期:——
irradiation initiates E–Z 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
当使用菲作为调节剂时,烯丙基和丙烯酸底物可以通过顺序的双色光化学方法以高选择性被有效地转化为乙酰丙酸酯或丁烯酸酯的衍生物。因此,UV-A光诱导的交叉复分解(CM)耦合了丙烯酸和烯丙基的对应物,随后的UV-C辐照引发了E – Z碳-碳双键的异构化,然后是两个相互竞争的过程之一;即,通过酯交换或1,5-H转移和互变异构进行环化。量子化学计算表明,中间体对于环化而言发生了强烈的蓝移,而对于1,5-H转移反应则发生了红移。因此,通过采用吸收UV-C的菲来延迟双键迁移,会导致选择性的新型发散性全光化学途径,用于合成无处不在的天然产物的基本结构图案。