Synthesis of trisubstituted 1,3-oxazin-6-ones via base-catalyzed ring-opening annulation of cyclopropenones with N-(pivaloyloxy)amides

Phosphine-Catalyzed Ring-Opening Regioselective Addition of Cyclopropenones with Amides

“…To validate the feasibility of the hypothesis, we carried out initial investigations using diphenylcyclopropenone and N -(benzyloxy)-2-bromo-2-methylpropanamide as the pilot substrates (Table ). To our knowledge, N -(benzyloxy)-2-bromo-2-methylpropanamide 1a , an in situ formed azaoxyallyl cation, was a type of synthons applied in cycloaddition reaction . When the reaction was performed in Ph 3 P (20 mol %) and dichloromethane (DCM) as a solvent, together with K 2 CO 3 (1.2 equiv) as the base, it only produced α,β-unsaturated ester 3aa in 81% yield, and no cycloaddition product was detected (entry 1).…”

Heterocycles from cyclopropenones

“…During the ring opening, B lost a pivalate anion to give ketene C, which rearranged to form the nal structure (121z), via a 6p electrocyclization process, as shown in Scheme 79. 118 In 2019, substituted thiazinane derivatives 128a-e were successfully synthesized by Hassan Scheme 75 Scandium-catalyzed synthesis of substituted 1,3-oxazin-6-ones 121k-q. Reagent and conditions: A ¼ CsOAc (1 equiv.…”

“…During the ring opening, B lost a pivalate anion to give ketene C , which rearranged to form the final structure ( 121z ), via a 6π electrocyclization process, as shown in Scheme 79. 118…”

M-CPOnes: Transition Metal Complexes with Cyclopropenone-Based Ligands for Light-Triggered Carbon Monoxide Release

“…[22][23][24] While cyclopropenones 25,26 undergo efficient photolysis 27,28 upon irradiation with light resulting in carbon monoxide release and alkyne formation, they have been largely overlooked as CORMs. 16 Instead, cyclopropenones have found use across different fields from organic chemistry (as substrates in annulations, [29][30][31][32][33] metal-catalysed ringopening reactions, 34 cycloaddition reactions 35,36 and allene syntheses 37,38 as well as catalysts for nucleophilic substitutions 39,40 ) to material science 18,41,42 and biorthogonal chemistry. [43][44][45][46][47][48] Cyclopropenones are appealing as prospective CORMs not only for their efficient photodecarbonylation but since they can be prepared via various synthetic methods (e.g.…”