Sulfone promoted Rh(iii)-catalyzed C–H activation and base assisted 1,5-H shift strategy for the construction of seven-membered rings

Abstract

A facile synthesis of thiepine sulfones is described. It relies on a sequence of Rh(III)-catalyzed C-H cleavage, 1,5-H shift, and intramolecular allene insertion. As a result of extremely readily accessible starting materials and convenient operation, this protocol should be an appealing strategy in organic synthesis.

A comprehensive overview of directing groups applied in metal-catalysed C–H functionalisation chemistry

“…An additional attracting example of sulfone-directed intramolecular transformation was reported in 2015 by Zhou ( Scheme 166B ). 1030 This cascade-type reaction involves sulfone-directed metallation, followed by base-assisted 1,5-H shift affording allene intermediates. Insertion into the C–Rh bond finally delivers seven-membered heteroaromatic products such as benzothiepines.…”

Recent Advances in [Cp*MIII] (M = Co, Rh, Ir)‐Catalyzed Intramolecular Annulation Through C–H Activation

“…The group of Zhou reported an original approach towards the synthesis of thiepine sulfone derivatives . They used a sulfone as directing group and an allene as partner, generated in situ by a 1,5‐H shift under basic conditions (Scheme ).…”

Computationally-Guided Development of a Chelated NHC-P Iridium(I) Complex for the Directed Hydrogen Isotope Exchange of Aryl Sulfones

“… 7 For example, sulfones are present in antibiotics, such as dapsone and dextrosulphenidol, 8a , 8b and are also components within a range of other medicines, including the non-steroidal anti-inflammatory, rofecoxib, and the retinoid, sumarotene ( Figure 2 ). 8c , 8d However, the capacity to exploit the sulfone as a directing group in C–H activation processes, 9 including HIE, 10 is currently vastly undermet. With specific regard to HIE, Pfaltz and Muri have reported an N , P -chelated Ir(I) catalyst, which mediates deuterium labeling of a series of substrates, including one example of a simple aryl (phenyl methyl) sulfone.…”