González-Rodríguez Carlos, Escalante Luz, Varela Jesús A, Castedo Luis, Saá Carlos
Departamento de Quimica Organica, Facultad de Quimica, Universidad de Santiago de Compostela, 15782 Santiago de Compostela, Spain.
Org Lett. 2009 Apr 2;11(7):1531-3. doi: 10.1021/ol900142r.
TFA-promoted exo carbocyclizations of nonterminal 7-alkynals gave good to excellent yields of seven-membered cycloalkenones, a medium-sized functionalized ring present in natural products with relevant pharmacological properties. Nonterminal 5- and 6-alkynals also gave very good yields of the corresponding exo cyclopentenones and cyclohexenones. On the other hand, terminal 5-alkynals gave endo carbocyclizations to cyclohexenones. These carbocyclizations can be considered as tandem alkyne hydration/aldol condensation processes.
三氟乙酸促进的非末端7-炔醛的分子外环化反应，生成七元环烯酮的产率良好至优异，七元环烯酮是一种存在于具有相关药理特性的天然产物中的中等大小的官能化环。非末端5-和6-炔醛生成相应分子外环戊烯酮和环己烯酮的产率也非常高。另一方面，末端5-炔醛发生分子内环化生成环己烯酮。这些碳环化反应可被视为串联的炔烃水合/羟醛缩合过程。
