Brønsted Acid-promoted intramolecular carbocyclization of alkynals leading to cyclic enones.
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.
González-Rodríguez
Carlos
C
Departamento de Quimica Organica, Facultad de Quimica, Universidad de Santiago de Compostela, 15782 Santiago de Compostela, Spain.
Escalante
Luz
L
Varela
Jesús A
JA
Castedo
Luis
L
Saá
Carlos
C