Stereoselective Multiple Functionalization of Pyrylium Salts by Domino Reactions with 2-Silyloxybuta-1,3-dienes
摘要:
Six at a time! Up to six stereogenic centers can be diastereoselectively formed in one step in three-component domino reactions of 4-silyloxypyrylium triflates with 2-silyloxybuta-1,3-dienes. Annulated or bridged ring systems such as 1 and 2, respectively, can be formed with high selectivity. R1 =silyl group; R2 , R3 =organyl group.
Ru-Catalyzed Cyclization of Terminal Alkynals to Cycloalkenes
摘要:
Cycloalkenes can be efficiently prepared by a new Ru-catalyzed cyclization of terminal alkynals. Under appropriate conditions, cycloisomerizations to conjugated aldehydes may be observed. Both processes involve catalytic Ru vinylidenes.
Ru-Catalyzed Cyclization of Terminal Alkynals to Cycloalkenes
作者:Jesús A. Varela、Carlos González-Rodríguez、Silvia G. Rubín、Luis Castedo、Carlos Saá
DOI:10.1021/ja0610434
日期:2006.8.1
Cycloalkenes can be efficiently prepared by a new Ru-catalyzed cyclization of terminal alkynals. Under appropriate conditions, cycloisomerizations to conjugated aldehydes may be observed. Both processes involve catalytic Ru vinylidenes.
Stereoselective Multiple Functionalization of Pyrylium Salts by Domino Reactions with 2-Silyloxybuta-1,3-dienes
Six at a time! Up to six stereogenic centers can be diastereoselectively formed in one step in three-component domino reactions of 4-silyloxypyrylium triflates with 2-silyloxybuta-1,3-dienes. Annulated or bridged ring systems such as 1 and 2, respectively, can be formed with high selectivity. R1 =silyl group; R2 , R3 =organyl group.
Brønsted Acid-Promoted Intramolecular Carbocyclization of Alkynals Leading to Cyclic Enones
作者:Carlos González-Rodríguez、Luz Escalante、Jesús A. Varela、Luis Castedo、Carlos Saá
DOI:10.1021/ol900142r
日期:2009.4.2
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.