The first synthesis of highly strained spirocyclobutane-pyrrolines via a palladium-catalyzed tandem Narasaka−Heck/ C(sp 3 or sp 2 )−H activation reaction is reported here. The key step in this transformation is the activation of a δ-C−H bond via an in situ generated σ-alkyl-Pd(II) species to form a five-membered spiropalladacycle intermediate. The concerted metalation-deprotonation (CMD) process, rate-determining step, and energy barrier of the entire reaction were explored by density functional theory (DFT) calculations. Moreover, a series of control experiments was conducted to probe the rate-determining step and reversibility of the C(sp 3 )−H activation step.

A novel copper(II) trifluoromethanesulfonate-catalyzed, high-efficiency, and atom-economical synthesis of valuable organophosphorus compounds via cascade annulation of propargylic alcohols with diphenylphosphine oxide is described. This protocol, which has a good functional-group compatibility and insensitivity to an ambient atmosphere, provides a simple and direct pathway to the products, organophosphorus compounds, in good yields under mild conditions. The method could be efficiently scaled up to gram scale, thus highlighting a potential application of this methodology.

A novel visible-light-induced palladium-catalyzed Heck reaction for bromine sugars and aryl olefins with high regioand stereochemistry selectivity for the preparation of C-glycosyl styrene is described. This reaction takes place in one step at room temperature by using a simple and readily available starting material. This protocol can be scaled up to a wide range of glycosyl bromide donors and aryl olefin substrates. Mechanistic studies indicate that a radical addition pathway is involved.C-Glycosides, in which the glycosidic oxygen is replaced by a carbon atom, have received a great deal of attention 1 because of the crucial roles of carbohydrates in resisting metabolic degradation and biological activities. 2 Compared with N-or Oglycosides, C-glycosides show an obvious enhancement in both in vitro and in vivo stability. Despite the significant methods available for constructing C-glycosides, a stereoselective and efficient method is still challenging and lags far behind that for O-or N-glycosides. 3 Over the past few decades, synthetic methods for C-glycosides have mainly concentrated on transition-metal-catalyzed 4 cross-coupling reactions. In particular, the construction of aryl C-glycosides 5 has undergone remarkable development. In 2008, Gagnéand co-workers reported a Ni-catalyzed Negishi cross-coupling approach for the synthesis of C-alkyl and C-aryl glycosides 6 (Scheme 1, Gagne's work). Recently, an efficient and stereoselective synthesis via palladium-catalyzed C−H glycosylation of Caryl glycosides was reported by Chen and co-workers. 7 In addition, the groups of Gagne, Cossy, and Nakamura also explored nickel-, 8 cobalt-, 9 and iron-catalyzed 10 cross-coupling reactions through generation of glycosyl radical intermediates to synthesize C-aryl glycosides.Although synthetic routes for C-aryl glycosides have been widely explored, the C-glycosyl styrenes, which are versatile starting compounds for, e.g., varitriol, 11 C-glycosyl aldehydes, 12 UDP sugar derivatives, 13 pyranopyran carbohydrate amino acids, 14 and some natural products, 15 remain challenging. At the outset, an intramolecular radical cyclization strategy was applied to prepare C-glycopyranosyl styrenes. In 1991, Stork and co-workers 16 demonstrated a temporary silicon connection for constructing C-glycopyranosyl styrenes that undergo an intramolecular radical process. Soon afterward, the Beau group 17 used a similar strategy to realize samarium iodidepromoted radical cyclization for the formation of the Cglycopyranosyl bond. Over the past few years, some other

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A silver-catalyzed formal [3 + 3] annulation of 3-methyleneisoindolin-1-one with alkynol for the synthesis of 1,5-dihydroindolizin-3­(2H)-one derivatives is disclosed. The protocol allows practical synthesis of N-heterocyclic scaffolds with a broad scope of functional groups and could be efficiently scaled up to gram scale, which incarnates a potential application of this methodology. In addition, a range of chlorine anion substitution of alkenes can be constructed by adjusting the structure of the alkynol substrates with the use of TMSCl.

An innovative 1,5-HAT cascade strategy has been advanced for the nickel-catalyzed distal arylation via cross-electrophile coupling. Through specific migration, the remote C­(sp3)–H bond is regioselectively activated, and Ar–I as the available electrophile is used for the construction of the C­(sp3)–C­(sp2) bond. This method also has broad applicability for benzylic and aliphatic N-fluorocarboxamides with yields up to 80%. Furthermore, a series of control experiments demonstrated that this reaction is probably initiated by a radical process.

A novel palladium-catalyzed spirocyclization through sequential Narasaka-Heck, C-H activation and [4+2] annulation has been developed. In this reaction, cheap and readily available 2-chlorobenzoic acid or ethyl phenylpropiolate was employed as...

An operationally simple radical difluoroalkylation/trifluoromethylation and alkynylation of unactivated alkenes under mild conditions has been developed. Through this protocol, a series of CF2/CF3‐ substituted linear alkynyl ketones were synthesized via a unique 1,2‐alkynyl radical migration. Notably, no transition‐ metal catalyst is needed in the developed reaction system, and excellent functional group compatibility was observed.magnified image