α,β-Enone Borylation by Bis(Pinacolato)Diboron Catalyzed by Cu3(BTC)2 Using Cesium Carbonate as a Base

Cu3(BTC)2 (BTC: 1,3,5-benzenetricarboxylate) as a heterogeneous catalyst in the presence of cesium carbonate as a base is reported for the borylation of α,β-conjugated enones by bis(pinacolato)diboron (B2pin2). According to the hot-filtration test, Cu3(BTC)2 is acting as a heterogeneous catalyst. Further, Cu3(BTC)2 exhibits a wide substrate scope and can be reused in consecutive runs, maintaining a crystal structure as evidenced by powder X-ray diffraction (XRD). A suitable mechanism is also proposed for this transformation using Cu3(BTC)2 as catalyst.

Cesium Carbonate Mediated Cyclization of Oxotryptamines with Allenoates: an Approach to Aza-Spiro[5.7]-cycloheptane Oxindole

A new method for the synthesis of aza-spiro[5.7]-cycloheptane oxindoles in up to 96% yield with broad substrate scope has been disclosed in this paper using oxotryptamines as dual nucleophilic reagents to react with allenoates in the presence of cesium carbonate under mild conditions. According to the previous works and deprotonation tracing experiment, the plausible reaction mechanisms have been proposed.

Ni–Catalyzed Difunctionalization of Alkynyl Bromides with Thiosulfonates and N-Arylthio Succinimides: A Convenient Synthesis of 1,2-Thiosulfonylethenes and 1,1-Dithioethenes

An efficient Ni-catalyzed vicinal thiosulfonylation of 1-bromoalkynes with thiosulfonates in the presence of cesium carbonate has been described. An operationally simple and highly regioselective atom transfer radical addition (ATRA) of alkynyl bromides provided a wide range of (E)-1,2-thiosulfonylethenes (alpha-aryl-beta-thioarylvinyl sulfones) in moderate to high yields. The immense substrate scope of both alkynyl bromides and thiosulfonates were explored with a broad range of functional groups. Also, the indole derived 1,1-bromoalkenes were also successfully sightseen in 1,2-thiosulfonylation process. Moreover, the Ni-catalyzed geminal-dithiolation of alkynyl bromides with N-arylthio succinimides, thus providing 1,1-dithioalkenes in high yields. The present protocol is reliable at gram-scale, and a sequential one-pot bromination and thiosulfonylation of phenylacetylene have also been achieved in scale-up synthesis. A plausible mechanism is proposed to rationalize the experimental outcome and control experiments for the vicinal thiosulfonylation.

Silylative aromatization of p-quinone methides under metal and solvent free conditions

A novel and efficient synthetic protocol is reported for the synthesis of benzyl silanes from readily available silylborane and p-quinone methides using 5% cesium carbonate under solvent-free conditions.

A practicable synthesis of 2,3-disubstituted 1,4-dioxane bearing carbonyl functionality from α,β-unsaturated ketones using Williamson strategy

We have observed that the reagent combination of NaIO4 and NH2OH•HCl reacts with α,β-unsaturated ketones followed by the nucleophile ethylene glycol allowing the synthesis of 2,3-disubstituted 1,4-dioxane using cesium carbonate...