Palladium‐Catalyzed Carboxy‐Alkynylation of Propargylic Amines Using Carbonate Salts as Carbon Dioxide Source

Abstract

A palladium‐catalyzed multicomponent reaction of propargylic amines, alkynyl bromides and cesium hydrogen carbonate to access oxazolidinones is reported. In contrast to previous reports, only a slight excess of cesium hydrogen carbonate is used as a surrogate of carbon dioxide. The reaction gives access to oxazolidinones bearing alkyl‐ and aryl polysubstituted enynes in good yield and very high E stereoselectivity.

Trimethylsilanolate-Promoted Activation of Alkynyl Trimethylsilanes: Hiyama-Type Sonogashira Cross-Coupling for the Synthesis of Arylene–Ethynylene-Linked Porphyrin Arrays

“…In a Schlenk flask, a mixture of 2,6-bis­(4 ′ ,4 ′ ,5 ′ ,5 ′ -tetramethyl-[1 ′ ,3 ′ ,2 ′ ]­dioxaborolan-2 ′ -yl)­azulene (prepared by the literature method, , 0.25 g, 0.64 mmol) and 2-triisopropylsilyl-1-bromoactylene (prepared by the literature method, 0.42 g, 1.6 mmol) in toluene (10 mL), ethanol (5 mL), and water (2 mL) was degassed by argon bubbling for 30 min (Scheme ). To the mixture, Pd­(PPh 3 ) 4 (38 mg, 33 μmol) and Cs 2 CO 3 (1.0 g, 3.1 mmol) were added before stirring at 80 °C for 20 h. The crude product was extracted with n -hexane, and the organic layer was dried over anhydrous sodium sulfate.…”

Facile Multicomponent Synthesis of Oxazolidinones from Primary Amines and Cesium (Hydrogen)Carbonate

“…Carbonate salts as C1 feedstock instead of carbon dioxide are known for a long time but have so far only rarely been applied to the synthesis of oxazolidinones. For example, propargyl amines and silyl alkynyl bromides have been used as starting materials in a palladium‐catalyzed protocol with cesium hydrogencarbonate replacing carbon dioxide [18] . Furthermore, potassium hydrogencarbonate as a C1 source was used in a copper‐catalyzed oxazolidinone formation starting with N ‐(2‐bromoallyl)amines [19] .…”

“…For example, propargyl amines and silyl alkynyl bromides have been used as starting materials in a palladium-catalyzed protocol with cesium hydrogencarbonate replacing carbon dioxide. [18] Furthermore, potassium hydro-gencarbonate as a C1 source was used in a copper-catalyzed oxazolidinone formation starting with N-(2bromoallyl)amines. [19] The conversion of an aliphatic primary amine into oxazolidinones with haloalkyl oxiranes reagents and base treatment was also reported using cesium or potassium carbonates.…”

C1 functionalization of imidazo heterocycles via carbon dioxide fixation

“…54,55 Carbonate salts as C 1 feedstocks instead of carbon dioxide have rarely been applied to the synthesis of oxazolidinones and especially to the case of oxazinanones. [56][57][58][59] Very interestingly, when we employed a salicyl aldehyde as our oxo-component in the GBB-3CR, we noticed that just treatment with NaHCO 3 in the absence of any metal-catalyst or metal-additive afforded the carbamates 3k-s in high yields (Scheme 3).…”