Cu-Catalyzed Asymmetric Borylative Cyclization of Cyclohexadienone-Containing 1,6-Enynes
摘要:
The first Cu-catalyzed asymmetric borylative cyclization of cyclohexadienone-containing 1,6-enynes is achieved through a tandem process: selective beta-borylation of propargylic ether and subsequent conjugate addition to cyclohexadienone. The reaction proceeds with excellent regioselectivity and enantioselectivity to afford an optically pure cis-hydrobenzofuran framework bearing alkenylboronate and enone substructures. Furthermore, the resulting bicyclic products could be converted to bridged and tricyclic ring structures. This method extends the realm of Cu-catalyzed asymmetric tandem reactions using bis(pinacolato)diboron (B(2)pin(2)).
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
Arylative Cyclization of Indole-1-carboxamides with 1,6-Enynes for the Synthesis of Polycyclic Indole Scaffolds
作者:Chatrala Ravikumar Reddy、Suresh Yarlagadda、Balasubramanian Sridhar、Basi V. Subba Reddy
DOI:10.1002/ejoc.201701029
日期:2017.10.17
A new alkyne annulation strategy has been developed for the synthesis of polycyclic indole derivatives through a cascade of C–H annulation and Michael addition reactions. This is the first report on sequential alkyne annulation and aza-Michael addition reactions of indole-1-carboxamides with alkyne tethered substrates.
Rhodium-catalyzedasymmetric desymmetrization Pauson–Khandreaction of C4-alkynyl-tethered cyclohexadienones has been developed as a novel strategy for access to fused 6–5–5 tricycles bearing three consecutive stereogenic centers. An array of chiral tricyclo[6.2.1.04,11]undecenes have been synthesized in high yields and enantioselectivities in a single step under mild conditions. This strategy employs
Rhodium-catalyzedasymmetrichydrogenation of alkyne-tethered cyclohexadienones enables highly regio- and enantioselective reductive cyclization to afford cis-hydrobenzofurans and cis-hydroindoles in high yields. Desymmetrization of 1,3-diyne-tethered cyclohexadienones was also explored, wherein the intramolecular coordination of a Rh complex with the cyclohexadienone ring induces exclusive regioselectivity
A formal [3 + 2] annulation of cyclohexadienone-tethered ynals is enabled by an N-heterocyclic carbene (NHC) catalyst, affording a tricyclo[6.2.1.04,11]undecane framework. This study represents the first demonstration of using C═C double bonds as the reaction partner in the NHC-catalyzed annulation of ynals. This strategy is characterized by mild reaction conditions and 100% atom economy as well as