Cationic Rhodium(I)/H<sub>8</sub>-binap Complex Catalyzed [2+2+2] Cycloadditions of 1,6- and 1,7-Diynes with Carbonyl Compounds
作者:Yousuke Otake、Rie Tanaka、Ken Tanaka
DOI:10.1002/ejoc.200900185
日期:2009.6
catalyzes [2+2+2] cycloadditions of a variety of 1,6- and 1,7-diynes with both electron-deficient and electron-rich carbonyl compounds, leading to dienones in high yield under mild reaction conditions. In the reactions with acyl phosphonates, the reactivity of 1,6- and 1,7-diynes was highly dependent on their own structures. The addition of chelating diethyl oxalate effectively promoted the [2+2+2] cycloadditions
Palladium/monophosphine complexes catalyze trans-selective arylative, alkenylative, and alkylativecyclization reactions of alkynals and alkynones with organoboronic reagents. These reactions afford six-membered allylic alcohols with endo-tri- or tetrasubstituted olefin groups and/or five-membered counterparts with exo olefin groups. The ratios of these products are dramatically affected by alkyne
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.
Tanaka, Rie; Noguchi, Keiichi; Tanaka, Ken, Journal of the American Chemical Society, 2010, vol. 132, p. 1238 - 1239