Synlett

In this study, a pentacyclic keto-olefin was treated with thallium(III) nitrate trihydrate, resulting in the formation of mono ring-expanded product. However, when the corresponding dialkene was treated with thallium(III) nitrate trihydrate, an unexpected ring-closure product was obtained instead of the expected double ring-expanded product. The use of the Tebbe reagent facilitated the olefination of hindered and enolizable cage dione derivatives, converting both keto moieties into methylene groups and forming the desired diolefin. Notably, conventional Wittig reagents proved to be ineffective in the olefination sequence with cage diones.

Numerous reports invoke CuIII–F intermediates engaging in oxidative cross-couplings mediated by low/mid-valent copper and formal sources of ‘F+’ oxidants. These elusive and typically instable CuIII fluorides have been rarely characterized or spectroscopically identified, making their existence and participation within catalytic cycles somehow questionable. We have authenticated a stable organocopper(III) fluoride that undergoes Csp–CF3 bond formation upon addition of silyl-capped alkynes following a 2 e– CuIII/CuI redox shuttle. This finding strongly supports the intermediacy of CuIII fluorides in C–C coupling. We review herein the state of the art about well-defined CuIII fluorides enabling cross-coupling reactions.1 Introduction2 Brief History of Coupling-Competent CuIII Fluorides3 Design of an Isolable – yet Reactive – Organocopper(III) Fluoride4 Alkyne Trifluoromethylation: Scope and Mechanism5 Extension to Aryl–CF3 and C–Heteroatom Couplings6 Summary and Outlook

Indium(III) triflate was found to be an efficient metal catalyst for the electrophilic substitution reaction of substituted indoles with various isatins or aryl aldehydes in acetonitrile solvent to afford the corresponding 3,3-diaryloxindoles or bis(indol-3-yl)methanes, respectively, in high yields at room temperature. This new procedure has remarkable features such as experimental simplicity, high conversions, good to excellent yields, short reaction times, and simple workup procedures

We herein developed a base-promoted cyclization reaction between N-acyl benzotriazoles and p-toluenesulfonylmethyl isocyanide (TosMIC) to afford 4,5-disubstituted oxazoles. In the presence of 3 equiv of K3PO4, the two readily available starting materials reacted in N,N-dimethylformamide at 80 °C to give 28 examples of 4-tosyl-5-aryl, -alkyl, or -alkenyl-substituted oxazoles in moderate to high yields.

We report a practical scalable synthesis of the natural product (±)-tylophorine by using an operationally simple protecting-group-free route from readily accessible starting materials. Synthesis of a cyclic N-acetyl diester compound through cyclization, followed by two key steps (decarboxylation and a Clemmensen reduction), provides access to the target molecule.

The selective construction of two C(sp3)–C(sp3) bonds through trimolecular cross-coupling of unactivated alkenes remains one of the most difficult challenges in organic synthesis. Despite previous advances in metal-catalyzed coupling for the dicarbofunctionalization of alkenes, dialkylation is still problematic due to the instability of the requisite metal–alkyl intermediate, which undergoes facile β-hydride elimination or protodemetalation. Recently, our group was successful in developing a bimolecular homolytic substitution (SH2) strategy that circumvents metal–alkyl side reactions and accomplishes the challenging cross-coupling of metal–alkyl intermediates with alkyl radicals in the absence of a directing auxiliary, permitting a highly regioselective dialkylation of unactivated alkenes.1 Introduction2 Nickel-Catalyzed Dicarbofunctionalization of Unactivated Alkenes3 Nickel-Catalyzed Dialkylation of Unactivated Alkenes4 Conclusions and Perspectives

An enzymatic method was developed for the synthesis of fluorene derivatives by benzannulation of indene dienes with benzoylacetonitrile in a nonaqueous solvent. Under the optimal reaction condition [indene diene (0.5 mmol), benzoylacetonitrile (0.5 mmol), ethanol (2 mL), lipase from porcine pancreas (5 mg), 50 °C, 24 h], fluorenes bearing various groups were obtained in satisfactory yields (83–93%). This method not only offers a significant advancement in the synthesis of fluorene derivatives, but also represents a new application of lipase in promiscuous enzyme catalysis.

Carbohydrates and their conjugates play important roles in life activities and drug development. Our group was committed to the general and effective glycosylation methods and their application in chemical biology using unsaturated glycosyl donors. In the past five years, we have reported several synthetic strategies with high stereoselectivity and milder conditions compared with previous works. In particular, high chemo-/regio- and stereoselective O-glycosylation, C-glycosylation and S-glycosylation could be achieved via palladium catalysis under open-air conditions at room temperature. In this Account, we will introduce our research progress in constructing four types of glycosides.1 Introduction2 Stereoselective Synthesis of O-Glycosides3 Stereoselective Synthesis of C-Glycosides4 Stereoselective Synthesis of N-Glycosides5 Stereoselective Synthesis of S-Glycosides6 Conclusion

A new heterogeneous polymeric disulfonimide was very easily synthesized from simple commercially available reagents. The new cost-effective catalytic material exhibited a tremendously enhanced reactivity in a benchmark Mukaiyama aldol reaction via silicon Lewis acid activation when compared with common acidic resins. Moreover, the reported polymeric disulfonimide exhibits outstanding robustness, as confirmed by its good thermal stability and excellent recyclability.

Synlett 2024; 35: V-DOI: 10.1055/s-0043-1774967Georg Thieme Verlag KG Rüdigerstraße 14, 70469 Stuttgart, GermanyArticle in Thieme eJournals:Table of contents