钯催化烯基苯并噁嗪酮基于内球型机理的线性和不对称烯丙基烷基化反应

烯基苯并噁嗪酮作为底物参与反应受到有机合成工作者的广泛关注.在过渡金属催化作用下,烯基苯并噁嗪酮脱除一分子二氧化碳,生成的两性离子中间体既可以被亲核试剂进攻,得到结构丰富的芳香胺,也可以作为1,4-偶极子与硫叶立德,缺电子烯烃或α,β-不饱和醛参与成环,分别生成相应的五元、六元或七元含氮杂环.后者广泛存在于农药、医药和...

Palladium-catalyzed enantioselective linear allylic alkylation of vinyl benzoxazinanones: An inner-sphere mechanism

Palladium-catalyzed asymmetric allylic alkylation (AAA) of vinyl benzoxazinanones has become an important strategy for the synthesis of chiral nitrogen-containing heterocycle compounds. Howev-er, the asymmetric synthesis of linear-selective products has rarely been reported. The simultane-ous control of regio-, E/Z- and enantioselectivities constitutes a major challenge and inhibits the advancement of this chemistry. Herein, we present a palladium-catalyzed AAA of vinyl benzoxazi-nanones with α-thiocyanato ketones, affording various chiral thiocyanates characterized with high linear-, E- and stereoselectivities. The reaction has a broad substrate scope and the chiral thiocya-nates can be transformed to useful heterocycles. Experimental and computational studies suggest an inner-sphere mechanism for AAA process, which results from the acidic and coordination effect of the nucleophilic substrates with palladium catalyst.