Catalyst-Controlled Regiodivergent Alkyne Insertion in the Context of C−H Activation and Diels-Alder Reactions: Synthesis of Fused and Bridged Cycles
作者:Xukai Zhou、Yupeng Pan、Xingwei Li
DOI:10.1002/anie.201704036
日期:2017.7.3
Rhodium(III)- and cobalt(III)-catalyzed C−Hactivation of indoles and coupling with 1,6-enynes is discussed. Under rhodium(III) catalysis, the alkyne insertion follows 2,1-regioselectivity with a subsequent type-I intramolecular Diels–Alder reaction (IMDA) to afford [6,5]-fused cycles. When catalyzed by the cobalt(III) congener, 1,2-insertion of the alkyne is preferred, and followed by a rare type-II
Tunable Diastereoselective Desymmetrization of Cyclohexadienones Triggered by Copper-Catalyzed Three-Component Coupling Reaction
作者:Raghunath Reddy Anugu、Rambabu Chegondi
DOI:10.1021/acs.joc.7b00936
日期:2017.7.7
copper-catalyzed [3 + 2]-cycloaddition followed by ketenimine formation and subsequent intramolecular conjugate addition. The cascade reaction provides cis-hydrobenzofurans in good yields with excellent diastereoselectivity. The exo- or endo-selectivity of bicyclic scaffolds depends on the selection of the base in the reaction. In addition, N-tethered bicyclic products further transformed into tricyclic compounds
Tunable Arylative Cyclization of 1,6-Enynes Triggered by Rhodium(III)-Catalyzed C–H Activation
作者:Yuki Fukui、Ping Liu、Qiang Liu、Zhi-Tao He、Nuo-Yi Wu、Ping Tian、Guo-Qiang Lin
DOI:10.1021/ja5072702
日期:2014.11.5
Two tunable arylative cyclizations of cyclohexadienone-containing 1,6-enynes are reported via rhodium(III)-catalyzed C-H activation of O-substituted N-hydroxybenzamides. The use of different O substituents, i.e. O-Piv and O-Me, on the directing group allows the formation of either tetracyclic isoquinolones through an (c)-Michael addition process or hydrobenzofurans through a (N)Michael addition process. Mechanistic investigations of these two cascade reactions clearly indicated that the C-H bond cleavage process was involved in the turnover-limiting step. Furthermore, the cyclization products could be subjected to various transformations for elaborating the pharmaceutically and synthetically valuable potential. This is the first example of a rhodium(III)-catalyzed arylative cyclization reaction of 1,6-enynes, and the results extend the application realm of Cp*Rh-III-catalyzed C-H activation cascade reactions.