Synthesis of Indenone Derivatives by Rh(III)-Catalyzed C–H Functionalization of Sulfoxonium Ylides with 1,3-Diynes

Abstract

The transition-metal-catalyzed C−H functionalization of sulfoxonium ylides with alkynes formally participates in [4 + 2] annulations to deliver the naphthol scaffolds. In contrast, herein we disclose the first Rh(III)-catalyzed C−H activation, followed by redox-neutral [3 + 2] annulation of sulfoxonium ylides with 1,3diynes, which delivers the alkynated indenone derivatives. This protocol features a good functional group tolerance, a broad substrate scope, moderate to excellent yields, and mild reaction conditions. The reaction mechanism was supported through ESI-HRMS by characterizing key intermediates in the catalytic cycle.

Diyne-steered switchable regioselectivity in cobalt(ii)-catalysed C(sp2)–H activation of amides with unsymmetrical 1,3-diynes

“…Our rationalisation of the observed regioselectivity is based on our previous report 39 and literature precedent. [40][41][42][43][44][45][46] In our earlier work using symmetrical bulky diphenyl-and diphenoxy-1,3-diynes, the major regioisomers obtained each had the alkynyl substituent at the 3-position, ortho to the amide nitrogen and its pendent quinolinyl directing group. The steric bulk of the directing group makes the approach of the diyne for metallacycle formation easier with the bulky substituent furthest from the quinolinyl moiety.…”

“…37 After these initial developments, research teams have disclosed a range of interesting examples with symmetrical 1,3-diynes (Scheme 1a). [38][39][40][41][42] Nonetheless, the use of unsymmetrical 1,3-diynes has been limited. This may be due to the inherent possibility of metalloalkynylation through two similar sites, leading to several possible regioisomers (Fig.…”

1,3‐Diynes: A Versatile Precursor in Transition‐Metal Catalyzed (Mediated) C−H Functionalizations

“…The synthetic efficiency of the methodology further demonstrated by the synthesis of diverse synthetic analogues, which are the core structures of many biologically active compounds (Scheme 52). [43] The authors proposed the following catalytic cycle (Scheme 53), which is supported through ESI-HRMS by characterizing all the key intermediates in the catalytic cycle. Coordination of the carbonyl oxygen atom of sulfoxonium…”

“…The synthetic efficiency of the methodology further demonstrated by the synthesis of diverse synthetic analogues, which are the core structures of many biologically active compounds (Scheme 52). [43] …”

Rh(III)‐Catalyzed Chemodivergent Coupling of Sulfoxonium Ylides and Acryloyl Silanes

“…For example, Chatanis group reported a Rh(III)‐catalyzed reaction of sulfoxonium ylides with alkenes to afford indanone derivatives [12a] (Scheme 1a). Subsequently, Yu, [12b] Prabhu [12c] and Cheng [12d] demonstrated the use of sulfoxonium ylides as TDG to synthesize polycyclic compounds in a domino fashion, respectively (Scheme 1b, Scheme 1c, Scheme 1d), etc [12e–h] . Inspired by these elegant pioneering studies and the ubiquity of indanone cores in biologically active compounds, we envisaged the possibility of C−H activation/annulation using sulfoxonium ylides as C4 synthons to access indanone‐fused polycyclic compounds.…”