Furans Conjugated with Bulky Aromatic Systems: One‐Pot Synthesis from Ketones and Acetylene

Abstract

Ketones with bulky aromatic, heteroaromatic and ferrocene substituents react with acetylene in the presence of a KOH/DMSO super-base suspension (90 °C, 15 min) to give polysubstituted furans in up to 86 % isolated yields in a one-pot fashion. This assembly of the furan scaffold involves a domino sequence in which one molecule of ketone reacts with two molecules of acetylene.

Multimolecular Self-Organization of 1-Acetyl-1,3-bis(haloarylamines) in KOH/DMSO System: From Acetylene Gas and o-Halo Arylamines toward a Higher Molecular Complexity and Diversity

“…Under superbase conditions, acetylene behaves as a triggering, driving, and organizing molecule toward other reactants. Examples of this phenomenon are one-pot assembly of N -vinyl pyrroles, dioxabicyclooctanes, acylcyclopentenols, substituted furans, and azabicyclohexanes from several molecules of acetylene and other reactants. These assemblies are started with the nucleophilic addition to the triple bond in simple and easy-to-handle superbase systems like alkali metal hydroxides or alkoxides/DMSO (p K a ≈ 30–32) .…”

Acetylene as a Driving and Organizing Molecule in One‐Pot Transition‐Metal‐Free Synthesis of Furans using Chalcones and their Analogues

“…[10] Despite the existing plethora of methods for the constructiono ft he furan ring, [11] importance of these compounds demands for continuous search and development of more simple and modulars yntheses in terms of PASE approach, [1] especially those allowing diversification of their structure.Recently,w eh ave disclosed one-pott ransition-metal-free assembly of furans from ketones and two molecules of acetylene in KOH/DMSOc atalytic system. [12] The key intermediates of this cascade reaction were postulated to be a,b-ethylenic ketones generated by the previously discovered base-catalyzed addition of ketones to acetylenes. [13] Here we report that verifica-Supportinginformation for this article can be found under: https://doi.…”

“…Recently,w eh ave disclosed one-pott ransition-metal-free assembly of furans from ketones and two molecules of acetylene in KOH/DMSOc atalytic system. [12] The key intermediates of this cascade reaction were postulated to be a,b-ethylenic ketones generated by the previously discovered base-catalyzed addition of ketones to acetylenes. [13] Here we report that verifica-Supportinginformation for this article can be found under: https://doi.…”

“…The cascade assembly of the furan ring (Scheme 1) is likely initiatedb yt he addition of acetylide anion to electron-deficient C=Cb ond (an analogue of the Favorsky ethynylation of the activated double bond C=O) and the enolate formed A is intramolecularly vinylated at its oxygen site by the acetylenic moiety to close the methylenedihydrofurani ntermediate B, which prototropically aromatizes. The acetylene molecule, due to its dual nature, [12,15,16] plays here ad riving and organizing role:f irst, behaving as an ucleophile (in its deprotonation form) and, then, in the ring-closure stage as an electrophile accepting the attack of oxygen-centereda nion.…”

“…The structureo ft his byproduct witnessest hat during the reaction, retro-condensation of chalcone 1l (Scheme2)o ccurs and 2-acetylthiopene thus formed further undergo the condensation with two molecules of acetylenes to close the furan ring (Scheme 1) as shown in ap revious publication. [12] [a] Reagents and conditions:c halcone 1 (5 mmol), NaO t Bu (5 mmol, 0.48 g), DMSO (50 mL), 70 8C, 15 min, initial pressure of acetylene at ambient temperature was % 10 atmand maximal pressure at the reactiont emperature was % 12 atm (stirredr eactor). [b] Isolated yield afterc olumn chromatography.…”