DBU-mediated [4 + 1] annulations of donor–acceptor cyclopropanes with carbon disulfide or thiourea for synthesis of 2-aminothiophene-3-carboxylates

Abstract

DBU-mediated [4 + 1] annulations of donor-acceptor cyclopropanes with carbon disulfide or thiourea to form 2-aminothiophene-3-carboxylate derivatives have been discovered. This reaction proceeds via the ring opening of donor-acceptor cyclopropanes to produce a 2-(iminomethylene)but-3-enoate intermediate, followed by the attack of an S-nucleophile for regioselective intermolecular nucleophilic addition, intramolecular S-nucleophilic addition, and final aromatization. A variety of functional groups could be tolerated under the reaction conditions.

Stereoselective Synthesis of 4,5‐Dihydroisoxazole Derivatives from 1,1‐Dicyanocyclopropanes and Hydroxylamine Hydrochloride

“…Thin layer chromatography (TLC) was used to monitor all reactions. These reported methods were used for the preparation of substituted cyclopropane‐1,1‐dicarbonitriles 7a – 7e , [97–112] other reagents and solvents were purchased from commercial suppliers and purified by standard techniques.…”

“…to construct various carbo‐ and heterocyclic compounds, containing many natural compounds and their analogs. As easily available multifunctional D‐A cyclopropanes, 2‐acyl‐3‐aryl‐cyclo‐propane‐1,1‐dicarbonitriles and 2‐acyl‐3‐aryl‐1‐cyanocyclopropane‐1‐carboxylates [84–96] have attracted wide attention in the classical heterocycle syntheses [97–112] . Considering the driving forces for the development of these new routes, and in continuation of using multifunctional D‐A cyclopropanes in the synthesis of diverse and complex compounds, we envisioned an approach to access functionalized isoxazoline derivatives through a cyclization reaction of substituted 1,1‐dicyanocyclopropane derivatives and hydroxylamine hydrochloride.…”

Novel synthesis of highly functionalized cyclopentane derivatives via [3 + 2] cycloaddition reactions of donor–acceptor cyclopropanes and (E)-3-aryl-2-cyanoacrylates

“…4 Recently, we have reported the opening ring of 1-cyanocyclopropane-1-carboxylates promoted by various bases. [24][25][26][27] Among them is an efficient and straightforward synthetic protocol for the preparation of fully substituted cyclopentadienes via [3 + 2] cycloaddition of 1-cyanocyclopropane-1-carboxy esters with β-nitrostyrenes. 28 In continuation of our interests in constructing the heterocycles and carbocycles, based on our studies on the reactivity of 2-aroyl-3-aryl-1-cyanocyclopropane carbonates, we envisioned that the reaction of 2-aroyl-3-aryl-1-cyanocyclopropane carbonates with substituted 3-aryl -2-cyanoacrylates may offer an efficient approach to cyclopentane skeletons via [3 + 2] cycloadditions.…”

Annulation of 2-Aroyl D–A Cyclopropanes via Selectively Ring-Opening Process with o-Benzenediamines to Access Quinoxaline Derivatives

“…In the past decade, we made many efforts in the field of exploring novel organic reactions starting from 2-aroyl D–A cyclopropanes to construct different carbocycles and heterocycles . Motivated by the above achievements, continuing our investigation on using 2-aroyl-3-arylcyclopropane-1,1-dicarbonitriles as efficient building blocks for the construction of cyclic compounds, because quinoxalines exhibit remarkable biological properties, which are abundantly present in numerous natural products, bioactive, and pharmaceutical compounds (Figure ), we expected that quinoxaline derivatives could be synthesized directly from 2-aroyl D–A cyclopropanes and o -benzenediamines via selective ring-opening reactions …”