Facile synthesis of polysubstituted furans and dihydrofurans via cyclization of bromonitromethane with oxodienes

A facile approach to spiro[dihydrofuran-2,3'-oxindoles] via formal [4 + 1] annulation reaction of fused 1H-pyrrole-2,3-diones with diazooxindoles

“…With the above observations and the reported literature [24] as a basis, the formation of spirofuranoxindoles 3aa-ka was assumed as proceeding via two stages: (a) the nucleophilic Michael attack of the negatively charged this case, the base-promoted deprotonation of 3-bromooxindole (4) affords a highly nucleophilic intermediate, which undergoes Michael addition to FPD 1i, followed by intramolecular S N 2 attack [39][40][41][42][43] by the oxygen of the aroyl group (Scheme 5) to give the same diastereomer 3ia with a good 54% yield.…”

One-Pot Tandem Approach to Functionalized 3-Hydroxy-2-furanyl-acrylamides

“…Further, we proposed to extend the application of our method toward the generation of different 2-heteroarylfurans, which may be useful in medicinal or materials science . This characteristic feature of the reaction could be helpful to generate different valuable structures, which otherwise are difficult to be generated through previous approaches. − In all of these presumptions, the nature of heteroarylglyoxals 2 decides the fate of the furan-heteroaryl coupling product. For instance, different reactions tested between aroylacetonitriles 1 and 2-thiopheneglyoxals 2 resulted in the generation of different 2-(thiophen-2-yl)­furans (entries 3v–3aa , Table ).…”

“…On the basis of the preceding literature reports and the abovementioned results, a plausible reaction mechanism is proposed in Figure b. The initial step for the synthesis of 3-hydroxy-2-furanyl-acrylamides 3 involves the reaction of aroylacetonitrile 1 and OA 2 under a basic environment to form Knoevenagel adduct or Michael acceptor A .…”

“…Multisubstituted furans signify one of the important classes of five-membered heterocycles prevalent in natural products, pharmaceuticals, and agrochemicals and also represent useful intermediates in organic synthesis. 3 Consequently, a number of synthetic routes for the construction of polysubstituted furans have been reported, such as direct functionalization of furan rings, 4 Paal–Knorr synthesis, 5 Feist–Benary synthesis, 6 and metal-catalyzed cycloisomerization of alkynyl or allenyl substrates. 7 However, the investigation of innovative methods for the generation of polyfunctionalized furans is still highly desirable.…”

Diastereoselective Cyclopropanation through Michael Addition‐Initiated Ring Closure between α,α‐Dibromoketones and α,β‐Unsaturated Fischer Carbene Complexes

“…The MIRC reaction can also deliver a tetrasubstituted cyclopropane skeleton through the organocatalytic addition of aldehydes and bromomalonates to the Michael acceptors. Moreover, α‐oxo esters, nitromethane, phosphonate and pyridinium salts have been used as nucleophiles. Some examples of the MIRC cyclopropanation reaction between α,β‐unsaturated alkoxy carbenes, and 2‐methoxyfuran, sulfur ylides, lithiated epoxides, and lithiated dihalomethanes were used to prepare di‐, tri‐, and tetrasubstituted cyclopropanes.…”