作者:Pablo Wessig、Jutta Schwarz、Ute Lindemann、Max Holthausen
DOI:10.1055/s-2001-15061
日期:——
The first example of a C-O bond formation in the course of the Norrish-Yang reaction is described. Starting with readily accessible α-mesyloxy-β-keto amides 4, a δ-hydrogen transfer to the excited carbonyl group occurs and the diradicals thus formed undergo a very rapid elimination of methane sulfonic acid providing enolate diradicals. These ambidental enolate diradicals undergo a regioselective cyclization to 3,4-dihydro-2H-1,3-oxazin-4-ones 5. In two cases a cleavage reaction is observed, giving cyclic imines. The mechanism is investigated by means of DFT- and ab initio methods.
诺里什-杨反应过程中形成 C-O 键的第一个例子得到了描述。从容易获得的δ-甲酰氧基-δ-酮酰胺 4 开始,δ-氢转移到激发的羰基上,由此形成的二元酰胺迅速消除甲烷磺酸,提供了烯酸根二元酰胺。这些同源的烯酸二环化合物经过区域选择性环化反应生成 3,4-二氢-2H-1,3-恶嗪-4-酮 5。在两种情况下会发生裂解反应,生成环状亚胺。通过 DFT 和 ab initio 方法对其机理进行了研究。