Sulfide‐Directed Ir‐Catalyzed Vinylic sp² and Benzylic sp³ C−H Activation for the Construction of Sulfur‐Containing Medium‐Ring System

Abstract

Ir‐catalyzed transformations initiated by sulfur‐directed vinylic sp2 and benzylic sp3 C−H activation are disclosed that achieve the construction of sulfur‐containing seven‐ and eight‐membered systems. Allyl 2‐alkynylphenyl sulfides were transformed into dihydrobenzothiepines in 30–95 % yield, and 2‐alkynylaryl 2‐tolyl sulfides were converted into dibenzo[b,f]thiepines in 57–95 % yield along with double bond isomerization. In both reactions, the combination of Ir catalyst and sulfide moiety was a key to the facile cyclization.

Sulfur in Waste‐Free Sustainable Synthesis: Advancing Carbon–Carbon Coupling Techniques

“…Cationic iridium complexes are capable of effectively activating not only aryl C(sp 2 )À H (Scheme 8, entry a) and vinyl C(sp 2 )À H (Scheme 8, entry b1) and even C(sp 3 )À H (Scheme 8, entry b2) positions with the assistance of the sulfide sulfur atom as a part of the initial compound. [73,74] The presence of an alkyne moiety in the starting material promotes its incorporation into the coordination sphere of the metal and the formation of complex polycyclic structures. The configuration of the double bond in the structures of the desired products clearly indicates that the CÀ H activation stage precedes the activation of the triple bond, which means that the directing action of the sulfur atom in the described process is a necessary condition for the occurrence of this reaction.…”