Carbon dioxide-mediated synthesis of 3(2H)-furanones from diyne alcohols

Synthesis of tetronic acids from propargylic alcohols and CO2

A direct and practical synthesis of important tetronic acids from easily available propargylic alcohols and carbon dioxide is reported for the first time. This transition-metal-free transformation features high atom- and step-economy, mild reaction conditions, good functional group tolerance and high yield. Preliminary mechanistic studies suggest that the reaction proceeds via cyclization to give alkylidene cyclic carbonate, ring-opening and re-cyclization processes.

Silver(I)-Promoted Cascade Reaction of Propargylic Alcohols, Carbon Dioxide, and Vicinal Diols: Thermodynamically Favorable Route to Cyclic Carbonates

A silver(I)-promoted cascade reaction was developed for the synthesis of cyclic carbonates from terminal propargylic alcohols, carbon dioxide, and vicinal diols. Compared with direct condensation of vicinal diols with CO₂, this protocol provides a thermodynamically favorable route to cyclic carbonates and α-hydroxyl ketones in excellent yields (up to 97%) without the additional dehydration step. Such a cascade procedure proceeds presumably through initial reaction of propargylic alcohol with CO₂ and subsequent nucleophilic attack of vicinal alcohol on in situ-formed α-alkylidene cyclic carbonate, resulting in successive generation of α-alkylidene cyclic carbonate, unsymmetrical β-oxoalkyl carbonate, cyclic carbonate, and α-hydroxyl ketone.

Organocatalytic asymmetric domino Michael/O-alkylation reaction for the construction of succinimide substituted 3(2H)-furanones catalyzed by quinine

Asymmetric domino reaction of maleimides with γ-halogenated-β-ketoesters catalyzed by quinine is developed to give succinimide substituted 3(2H)-furanones in good enantioselectivities.

A Serendipitous Synthesis of Bis-Heterocyclic Spiro 3(2H)-Furanones

(Z) Enol triflates 6, 11b-d, (E) enol triflate 11e, and phenol triflate 11a, derived from β-keto esters or 2-carboalkoxy phenols, respectively, react with N-Boc 2-lithiopyrrolidine (5a), N-Boc N-methylaminomethyllithium (5b), or 2-lithio-1,3-dithiane (14) to afford 3(2H)-furanones in modest to good yields (38-81%). Product and carbanion reagent studies suggest that the 3(2H)-furanone is formed in a cascade of reactions involving nucleophilic acyl substitution, enolate formation, trifluoromethyl transfer, iminium or sulfenium ion formation, and subsequent ring closure to form the 3(2H)-furanone. The use of 2-lithio-1,3-dithiane affords a cyclic α-keto-S,S,O-orthoester in which the functionality can be selectively manipulated for synthetic applications.