Selective Formation of Triplet Alkyl Nitrenes from Photolysis of β-Azido-Propiophenone and Their Reactivity
作者:Pradeep N. D. Singh、Sarah M. Mandel、Jagadis Sankaranarayanan、Sivaramakrishnan Muthukrishnan、Mingxin Chang、Rachel M. Robinson、Paul M. Lahti、Bruce S. Ault、Anna D. Gudmundsdóttir
DOI:10.1021/ja077523s
日期:2007.12.1
formation of triplet alkyl nitrenes 2 that were detected directly with laser flash photolysis (lambdamax = 325 nm, tau = 27 ms) and ESR spectroscopy (|D/hc| = 1.64 cm-1, |E/hc| = 0.004 cm-1). Nitrenes 2 were further characterized with argon matrix isolation, isotope labeling, and molecular modeling. The triplet alkyl nitrenes are persistent intermediates that do not abstract H-atoms from the solvent but
具有内置敏化剂单元的 β-叠氮基苯丙酮衍生物 1 的光解导致选择性形成三线态烷基氮烯 2,可通过激光闪光光解(λmax = 325 nm,tau = 27 ms)和 ESR 光谱法 (| D/hc| = 1.64 cm-1,|E/hc| = 0.004 cm-1)。氮烯 2 进一步表征为氩气基质分离、同位素标记和分子建模。三线态烷基氮烯是持久性中间体,不会从溶剂中提取 H 原子,而是通过与另一个三线态氮烯二聚形成偶氮产物而不是与叠氮化物前体反应而发生衰变。偶氮二聚体互变异构并重排形成杂环化合物 3。 具有 n,pi* 构型的氮烯 2a 作为其酮敏化剂部分的最低三重激发态,经历分子内 1,4-H 原子抽象形成双基 6,通过氩气基质分离、同位素标记和分子建模鉴定。β-叠氮基-对甲氧基苯丙酮,其三线态敏化剂部分的 pi,pi* 最低激发态不经历任何二次光反应,但选择性地仅产生三线态烷基氮烯中间体,二聚形成