Synthesis of 1′-aryl-2′-(2-oxoindolin-3-yl)spiro[indoline-3,5′-pyrroline]-2,3′-dione via one-pot reaction of arylamines, acetone, and isatins

Pseudo five component reaction towards densely functionalized spiro[indole-3,2'-pyrrole] by picric acid, an efficient syn-diastereoselective catalyst: insight into the diastereoselection on C(sp3)-C(sp3) axial conformation

A new series of highly-functionalized spiro compounds of pyrrole were synthesized by a one pot, step-economic condensation of isatin, arylamine and β-keto ester catalyzed by wet picric acid. Initially, the reaction was proposed with an expectation of the formation of a multi-spiro heterocyclic framework of highly-substituted piperidine. However, the isomeric compound was characterized to be a five-membered pyrrole derivative with a diverse scope of variations having different types of substituents in the three components respectively. The possibility of formation of various diastereomers around the hindered single bond and the spiro carbon was limited, as only syn products syn-60 and syn-60' were isolated in all the reactions performed under the standard conditions. Probably the reactions were mediated by the si-facial formation of the bonds in a picric acid stabilized charge transfer complex transition state. Also, the manner a molecule achieves the most stabilized energy minimized arrangement with all its substituents in space was studied by DFT calculations where syn-60 was more stable than syn-60'. The studies on the formation of syn-60 and syn-60' were carried out by variation of electronic and steric factors in each of the components of the reactions.

Two-carbon ring expansion of isatin: a convenient construction of a dibenzo[b,d]azepinone scaffold

A unique two-carbon ring expansion of isatin has been achieved to conveniently construct the functionalized dibenzo[b,d]azepin-6-one scaffold in moderate to high yields, and the two carbon sources are different: one carbon is from the N-substituent of pyridinium bromide and the other is from indene-1,3-dione.

One-pot four-component reaction for convenient synthesis of functionalized 1-benzamidospiro[indoline-3,4'-pyridines]

The one-pot four-component reaction of benzohydrazide (2-picolinohydrazide), acetylenedicarboxylate, isatins and malononitrile (ethyl cyanoacetate) with triethylamine as base catalyst afforded functionalized 1-benzamidospiro[indoline-3,4'-pyridines] in good yields. (1)H NMR spectra indicated that an equilibrium of cis/trans-conformations exist in the obtained products.

Domino reactions of vinyl malononitriles with 3-phenacylideneoxindoles for efficient synthesis of functionalized spirocyclic oxindoles

The reactions of vinyl malononitriles with 3-phenacylideneoxindoles in ethanol in the presence of DBU as base resulted in the functionalized spirocyclic oxindoles through the domino Michael addition and intramolecular nucleophilic addition to cyano group. On the other hand, the similar reaction in the presence of piperidine as base afforded the simple Michael addition products in good yields. The stereochemistry of the spirooxindoles was established with (1)H NMR data and single crystal structures.

Synthesis of tetrahydropyrimidin-2-ones via FeCl3 catalyzed one-pot domino reaction of amines, methyl propiolate, aromatic aldehydes, and urea

Polysubstituted 3-arylaminoacrylate and tetrahydropyrimidin-2-one derivatives could be selectively produced from the one-pot domino reaction of arylamines, methyl propiolate, aromatic aldehydes, and urea in ethanol in the presence of FeCl3 as catalyst. Under similar reactions secondary amines such as morpholine and piperidine predominately afford tetrahydropyrimidin-2-one derivatives in good yields.

Four-component reaction of N-alkylimidazoles(N-alkylbenzimidazoles), dialkyl but-2-ynedioate, N-alkylisatins and malononitrile

Convenient synthesis of complex spirooxindolesviafour-component reactions ofN-alkylimidazoles(N-alkylbenzimidazoles), dialkyl but-2-ynedioate,N-alkylisatins and malononitrile.

Facile synthesis of functionalized spiro[indoline-3,2'-oxiran]-2-ones by Darzens reaction

A series of functionalized spiro[indoline-3,2'-oxiran]-2-ones was efficiently synthesized by Darzens reaction of phenacyl bromides with isatins both with N-alkyl groups and without N-substituent in the presence of potassium carbonate as a base catalyst. When two equivalents phenacyl bromides were used in the reaction, the N-substitution reaction of isatin also finished with the formation of spiro-oxirane-oxindoles.