Synthetic Approach for Constructing the 1-Oxygenated Carbazole Core and Its Application to the Preparation of Natural Alkaloids
摘要:
An efficient synthetic approach for the construction of the 1-oxygenated carbazole core is described. The condensation of cyclohexane-1,2-diones with a series of anilines yielded the corresponding 2-anilinocyclohex-2-en-1-ones, followed by the one-pot aromatization/methylation process of the latter to provide N-aryl-2-methoxyanilines. A palladium(II)-catalyzed cyclization of these N-aryl-2-methoxyanilines afforded the desired 1-methoxycarbazole frame in high overall yields. This protocol was implemented for the total synthesis of the naturally occurring glycozolicine and 6-methoxymurrayanine.
Synthetic Approach for Constructing the 1-Oxygenated Carbazole Core and Its Application to the Preparation of Natural Alkaloids
摘要:
An efficient synthetic approach for the construction of the 1-oxygenated carbazole core is described. The condensation of cyclohexane-1,2-diones with a series of anilines yielded the corresponding 2-anilinocyclohex-2-en-1-ones, followed by the one-pot aromatization/methylation process of the latter to provide N-aryl-2-methoxyanilines. A palladium(II)-catalyzed cyclization of these N-aryl-2-methoxyanilines afforded the desired 1-methoxycarbazole frame in high overall yields. This protocol was implemented for the total synthesis of the naturally occurring glycozolicine and 6-methoxymurrayanine.
(<i>t</i>-Bu)<sub>2</sub>PNP(<i>i</i>-BuNCH<sub>2</sub>CH<sub>2</sub>)<sub>3</sub>N: New Efficient Ligand for Palladium-Catalyzed C−N Couplings of Aryl and Heteroaryl Bromides and Chlorides and for Vinyl Bromides at Room Temperature
作者:Ch. Venkat Reddy、Jesudoss V. Kingston、John G. Verkade
DOI:10.1021/jo702367k
日期:2008.4.1
chlorides possessing base-sensitive substituents (nitro, ester, and keto) provide coupling products with bulky aryl amines in good to excellent yields. Aryl halides possessing other functional groups including cyano, amino, trifluoromethyl, and phenol, coupled with equal ease, producing highly functionalized amines in good to excellent yields. Moreover, an aryl chloro group can be preserved in the presence
twelve aryl(phenyl)iodonium salts in a systematic chemoselectivitystudy. A new “anti‐ortho effect” has been identified in the arylation of malonates. Several “dummy groups” have been found that give complete chemoselectivity in the transfer of the phenyl moiety, irrespective of the nucleophile. An aryl exchange in the diaryliodoniumsalts has been observed under certain arylation conditions. DFT calculations
An efficient synthetic approach for the construction of the 1-oxygenated carbazole core is described. The condensation of cyclohexane-1,2-diones with a series of anilines yielded the corresponding 2-anilinocyclohex-2-en-1-ones, followed by the one-pot aromatization/methylation process of the latter to provide N-aryl-2-methoxyanilines. A palladium(II)-catalyzed cyclization of these N-aryl-2-methoxyanilines afforded the desired 1-methoxycarbazole frame in high overall yields. This protocol was implemented for the total synthesis of the naturally occurring glycozolicine and 6-methoxymurrayanine.