Indoles and their analogues have been one of the most ubiquitous heterocycles during the past century,a nd extensive studies have been conducted to establish practical synthetic methods for their derivatives.I np articular,s elective functionalization of the poorly reactive benzenoid core over the pyrrole ring has been agreat challenge.Reported herein is an iridium-catalyzed direct alkynylation of the indole C4-and C7-positions with the assistance of sulfur directing groups.This transformation shows aw ide range of functional-group tolerance with exceptional site selectivity.T he directing group can be either easily removed or transformed after catalysis.The synthetic utility of the alkyne fragment is demonstrated by the derivatization into the core structure of natural indole alkaloids.Scheme 3. Effect of the directing groups for the C7-selectivealkynylation. DCM = dichloromethane.Scheme 4. Substrate scope for the C7-selectivea lkynylation.Scheme 5. Derivatization of the C4-alkynylated indole 3a.D MF = N,Ndimethylformamide.

A thioether-directed Rh(III)-catalyzed C4 selective C-H alkenylation of indoles via the formation of 5-membered metallacycle intermediates is reported. This protocol allows a wide functional group compatibility and broad substrate scope. The directing group can be readily removed or transformed into other functional groups after the C-H functionalization event. The catalytic method is also applicable to related heterocyclic systems involving benzo[ b]thiophene and benzo[ b]furan scaffolds.

Site-selective direct functionalization of an indole benzenoid core has been a great challenge due to its inherently poor reactivity. We herein demonstrate an iridium-catalyzed C4-selective acylmethylation of indoles using α-carbonyl sulfoxonium ylides as carbene precursors. This method exhibits high efficiency and broad functional group compatibility. The directing group was easily removed or converted to other functionalities after the catalysis. The potential synthetic utility of the coupling products was highlighted by constructing medium-sized polycyclic indoles.

The gold(i)-catalyzed reaction/rearrangement of allenyl ethers has been investigated in the presence of indoles. Either hydroindolylation or alkylation of an indole with the pendant group of allenyl ether has been observed. The reaction outcome seems to be decided mainly by the nature of the pendant group of the allenyl ether. Control experiments are indicative of an inner sphere mechanism for the hydroindolylation reaction.