Synthesis of cyclopentenones and butenolides by reaction of the lithium salt of P,P-diphenyl-P-(alkyl)(N-phenyl)phosphazenes with electrophilic double and triple bonds
作者:Julia M. Álvarez-Gutiérrez、Fernando López-Ortiz、Santiago García-Granda、Alejandra Rodríguez-González
DOI:10.1039/b005131o
日期:——
Lithium P,P-diphenyl-P-(alkyl)(N-phenyl)phosphazenes act as bidentate reagents towards electrophilic olefins and acetylenes. The reactions with dimethyl acetylenedicarboxylate (DMAD) and dimethyl maleate afford cyclopentenones, while with methyl benzoylpropiolate the products obtained are butenolides with a quaternary carbon atom in position 5 of the heterocycle. The use of less activated substrates (methyl phenylpropiolate, methyl cinnamate, and dimethyl oxalate) allowed the isolation of C-acylated aminoylide or phosphazene derivatives. A reaction mechanism is proposed based on a tandem process involving the regioselective C-acylation of the carbon α to the phosphorus, followed by a cyclisation process promoted by the intramolecular Michael addition of the nitrogen of the PN linkage to an electrophilic double or triple carbon–carbon bond.
Lithium P,P-二苯基-P-(烷基)(N-苯基)膦氮烯作为双齿试剂与亲电性烯烃和炔烃反应。与己二酸二甲酯(DMAD)和马来酸二甲酯反应生成环戊烯酮,而与甲基苯甲酰丙炔酸酯反应则得到含有四级碳原子在杂环位置5的丁烯内酯。使用活性较低的底物(甲基苯基丙炔酸酯、甲基肉桂酸酯和草酸二甲酯)允许分离出C-酰化氨基氮烯或膦氮烯衍生物。提出了一种反应机理,涉及区域选择性的C-酰化作用,即在磷的α碳上进行,随后通过PN键中氮原子的分子内迈克尔加成促进的环化过程与亲电性双键或三键碳-碳键反应。