In this work, we describe a Catellani-type C−H glycosylation to provide rapid access to various highly decorated α-C-(hetero)aryl glycosides in a modular and stereoselective manner (>90 examples). The termination step is flexible, which is demonstrated by ipso-Heck reaction, hydrogenation, Suzuki coupling, and Sonogashira coupling. Application of this methodology has been showcased by preparing glycoside−pharmacophore conjugates and a dapagliflozin analogue. Notably, the technology developed herein represents an unprecedented example of Catellani-type alkylation involving an S N 1 pathway.

A rhodium(III)-catalyzed C−H acylmethylation of tridentate [2,2′-bipyridine]-6-carboxamides was developed. A variety of [2,2′-bipyridine]-6-carboxamides could be monoalkylated exclusively at the C3 position with sulfoxonium ylides as carbene precursors, giving 3-alkylated products in high yields. This protocol proceeds through a rollover cyclometalation pathway, has a broad range scope of substrates, and exhibits excellent functional group tolerance.

The first successful example of deacylative annulation of 1,3-diones with sulfoxonium ylides was achieved through Ru(II)-catalyzed C-C bond activation. The excellent chemoselectivity and broad substrate scope render this method a practical and versatile approach for the preparation of (hetero)aryl and alkenyl substituted furans, which are valuable units in many biologically active compounds and functional materials. A preliminary mechanistic study reveals that this process involves a deacylative a-ruthenation to generate key alkyl Ru(II) intermediates with the release of a benzoic acid fragment.Scheme 2 Scope of 1,3-diones. Reaction conditions: 1 (0.1 mmol), 2a (0.2 mmol), MesCO 2 Li (0.15 mmol), and [RuCl 2 (p-cymene)] 2 (5 mol%) in toluene (2 mL) at 120 C in air for 24 h. This journal isScheme 3 Scope of sulfoxonium ylides. Reaction conditions: 1a (0.1 mmol), 2 (0.2 mmol), MesCO 2 Li (0.15 mmol), and [RuCl 2 (p-cymene)] 2 (5 mol%) in toluene (2 mL) at 120 C in air for 24 h.Scheme 4 Gram-scale reactions and control experiments.9106 | Chem. Sci., 2019, 10, 9104-9108This journal is

A ruthenium(II)-catalyzed annulation between two molecules of sulfoxonium ylides is achieved, generating a variety of substituted isocoumarins in reasonable yields. This strategy features dual C−H/C−C activation in one pot and has a wide substrate scope and good functional group tolerance.I socoumarin and its derivatives are important natural lactones, which are generally found in natural products as a basic structure. 1 It was found that compounds with an isocoumarin structure have a certain physiological activity, 2 which are widely used in the treatment of cancer, 3 allergies, 4 sterilization, 5 and other aspects. 6 In addition, they could be used as key synthetic intermediates in drug discovery. 7 Thus, the synthesis of compounds with such a skeleton has attracted great interest. 8 Among the many synthetic methods to access these compounds, the transition-metal-catalyzed C−H activation/annulation cascade reactions of benzoic acid derivatives with coupling partners represent one of the most powerful and straightforward methods to isocoumarins. However, the coupling partners are commonly limited to internal alkynes (Scheme 1a). 9 The use of coupling partners other than internal alkynes will greatly enhance the scope of metal-catalyzed synthesis of isocoumarins.Sulfoxonium ylides are carbene precursors that are easier to prepare and more stable and safer than diazonium compounds. 10 Sulfoxonium ylides have been used as alkylating reagents in a variety of reactions. 11−15 Since the first example of rhodium(III)-catalyzed C−H alkylation of arenes with sulfoxonium ylides was independently discovered by Aïssa 11 and Li, 12 sulfoxonium ylides have been widely used as alkylating reagents in transition-metal-catalyzed C−H functionalization of a range of arenes. 13 Recently, Li's work illuminated the method of synthesizing isocoumarins from Nmethoxybenzamides, using sulfoxonium ylides as coupling partners and rhodium(III) as a catalyst (Scheme 1b). 14 Subsequently, a method for the formation of isocoumarins via ruthenium(II)-catalyzed C−H activation/annulation of benzoic acids and sulfoxonium ylides was reported by Ackermann (Scheme 1c). 15 Inspired by the works of Li and Ackermann, we questioned whether sulfoxonium ylides could be able to serve as both arenes 16 and coupling partners in transition-metal-catalyzed C−H activation. As our ongoing interest in C−H activation 17 and C−C cleavage, 18 herein, we disclose a ruthenium(II)-catalyzed dual C−H/C−C activation of sulfoxonium ylides for the synthesis of isocoumarins (Scheme 1d). 19 We initiated our investigation on the model reaction of sulfoxonium ylide (1a) to optimize various reaction parameters. The results are summarized in Table 1. To our delight, under reaction conditions using [RuCl 2 (p-cymene)] 2 as the catalyst, 2,4,6-trimethylbenzoic acid (MesCO 2 H) being an additive, and Na 3 PO 4 as the base in HFIP at 110 °C under an air atmosphere for 24 h, the desired product (2a) was obtained in 78% yield (entry 1). Investigations on various solvents indicat...