An expedient synthesis of pyrrolidinyl spirooxindole grafted 3-nitrochromanes through 1,3-dipolar cycloaddition reaction of azomethine ylides

Azomethine Ylides-Versatile Synthons for Pyrrolidinyl-Heterocyclic Compounds

Azomethine ylides are nitrogen-based three-atom components commonly used in [3+2]-cycloaddition reactions with various unsaturated 2π-electron components. These reactions are highly regio- and stereoselective and have attracted the attention of organic chemists with respect to the construction of diverse heterocycles potentially bearing four new contiguous stereogenic centers. This review article complies the most important [3+2]-cycloaddition reactions of azomethine ylides with various olefinic, unsaturated 2π-electron components (acyclic, alicyclic, heterocyclic, and exocyclic ones) reported over the past two decades.

Selective construction of functionalized chromeno[3,4-b]pyrroles and benzo[c]chromenesviaa K3PO4promoted three-component reaction

A K₃PO₄promoted three-component reaction of pivaloylacetonitrile (benzoylacetonitrile), dialkyl but-2-ynedioates and 2-aryl-3-nitrochromenes afforded functionalized chromeno[3,4-b]pyrroles.

A regio- and stereocontrolled approach to the synthesis of 4-CF3-substituted spiro[chromeno[3,4-c]pyrrolidine-oxindoles]viareversible [3+2] cycloaddition of azomethine ylides generated from isatins and sarcosine to 3-nitro-2-(trifluoromethyl)-2H-chromenes

The first example of regio- and stereocontrolled synthesis of 4-CF₃-spiro[chromeno[3,4-c]pyrrolidine-oxindoles] with anticancer activity.

Convenient construction of tetrahydrochromeno[4',3':2,3]indolizino[8,7-b]indoles and tetrahydroindolizino[8,7-b]indoles via one-pot domino reaction

The functionalized tetrahydrochromeno[4',3':2,3]indolizino[8,7-b]indoles were conveniently synthesized in high yields by one-pot domino reaction of tryptamines, alkyl propiolates and 2-aryl-3-nitro-2H-chromenes. Under similar conditions, the one-pot reaction of tryptamines, alkyl propiolates and β-nitroalkenes resulted in functionalized tetrahydroindolizino[8,7-b]indoles. The reaction mechanism involved sequential generation of β-enamino ester, Michael addition, Pictet-Spengler reaction and annulation process. The reaction showed high atomic economy and met the goals of sustainable chemistry.

Molecular diversity of the domino annulation reaction of 2-aryl-3-nitrochromenes with pivaloylacetonitriles

In the presence of triethylamine, the domino annulation reaction of two molecules of pivaloylacetonitrile with one molecule of 2-aryl-3-nitrochromene in tetrahydrofuran resulted in the unprecedented imino-substituted dihydrofuro[2,3-c]chromene derivatives in high yields.

Construction of Spirooxindole Skeleton Through Intramolecular Dieckmann Cyclization

A highly efficient and direct approach was developed to construct the structurally diverse spirooxindole skeleton, which is an important basic motif in natural products. Both the 3,3'-pyrrolidonyl spirooxindoles and spiroindolin-2-one δ-lactones were smoothly obtained by the intramolecular Dieckmann cyclization of oxindoles in excellent yield under mild conditions.

Diastereoselective synthesis of benzo[d]chromeno[3′,4′:3,4]pyrrolo[2,1-b]thiazoles via cycloaddition reaction of benzothiazolium salts with 3-nitrochromenes

Diastereospecific synthesis of benzo[d]chromeno[3′,4′:3,4]pyrrolo[2,1-b]thiazoles via cycloaddition reaction of benzothiazolium salts with 3-nitrochromenes.

A convenient and rapid microwave-assisted synthesis of spirooxindoles in aqueous medium and their antimicrobial activities

An efficient, regioselective and diastereoselective synthesis of diversely functionalized spirooxindoles under microwave irradiation in aqueous medium; most of the compounds show significant antimicrobial activities.

Diastereoselective synthesis of spiro[benzo[d]pyrrolo[2,1-b]thiazole-3,3'-indolines] via cycloaddition reaction of N-phenacylbenzothiazolium bromides and 3-methyleneoxindoles

The domino cycloaddition reactions of N-phenacylbenzothiazolium bromides with 3-phenacylideneoxindoles or ethyl 2-(2-oxoindolin-3-ylidene)acetates in ethanol at room temperature in the presence of triethylamine as a base afforded functionalized spiro[benzo[d]pyrrolo[2,1-b]thiazole-3,3'-indolines] in good yields and with high diastereoselectivity. The similar reactions of N-phenacylthiazolium bromides with 3-phenacylideneoxindoles resulted in the corresponding functionalized spiro[indoline-3,7'-pyrrolo[2,1-b]thiazoles] in satisfactory yields and also with high diastereoselectivity.

Ultrasound-assisted sequential multicomponent strategy for the combinatorial synthesis of novel coumarin hybrids

The present investigation reports an easy access to a library of novel spiro-oxindole-pyrrolizine or pyrrolo[1,2-c]thiazole fused coumarin hybrid heterocycles through a one-pot sequential four-component reactions of 2,2-dimethyl-1,3-dioxane-4,6-dione, salicylaldehydes, isatins, and cyclic α-amino acids under ultrasound irradiation.