A new divergent intermolecular cascade annulation reaction of N-(arylsulfonyl)acrylamides with dual alkyl C(sp3)–H bonds for producing two types of five-membered rings, indanes and pyrrolidin-2-ones, is described. By using cycloalkanes and common alkanes as a one-carbon unit, an intermolecular [4+1] cascade carboannulation of N-(arylsulfonyl)acrylamides was achieved via a sequence of three C–H bond functionalization/aryl migration/desulfonylation that enables the formation of three C–C bonds and one N–H bond. When the one-carbon unit was changed to cycloalkyl ethers, the alternative intermolecular [4+1] cascade heteroannulation reaction occurred and allowed the construction of two C–C bonds and one C–N bond through dual C–H bond functionalization, aryl migration and desulfonylation cascades.

A series of functionalized pillar[5]arenes mono-pyridylimine derivatives with different lengths of diaminoalkylene units as the side chains on the pillar[5]arene's rim were conveniently synthesized. The investigation of 1H NMR spectra and single crystal structures indicated that the formation of free forms or pseudo[1]rotaxanes turned out to be controlled by both the axle lengths of diaminoalkylene chains and the solvent effect. The pillar[5]arene mono-pyridylimines with short hydrazinyl and diaminoethylene chains exist in free form. On the other hand, pillar[5]arene mono-pyridylimines with longer than diaminopropylene chains formed stable pseudo[1]rotaxanes both in solution and in the crystal state.Download high-res image (142KB)Download full-size image

In the presence of hexamethylphosphorous triamide, the reaction of isatin with arylidene pivaloylacetonitriles in dry methylene dichloride afforded functionalized spiro[cyclopropane-1,3′-indolines] in good yields and with high diastereoselectivity. Moreover, the similar reaction of isatins with isatylidene malononitriles predominately gave spiro[indoline-3,1′-cyclopropane-2′,3″-indolines] in very high yields with two indoline moieties in trans-configuration.

A series of copillar[5]arene mono-Schiff bases were conveniently synthesized by the condensation reaction of pillar[5]arene mono-oxyacetohydrazide with substituted salicylaldehydes, isatins, acetoacetone and terephthalaldehyde in refluxing ethanol. Determination of single crystal structures indicated that the chain unit of mono-Schiff base exists in the outside of the cavity of copillar[5]arene. The complexing ability of these Schiff base ligands to transition metal ions were investigated by UV spectra.

10α,20α-di(4-aminophenyl)calix[4]pyrroles were synthesized from the acid catalyzed cyclization of dialkyldipyrromethanes with p-nitroacetophenone and sequential hydrogenation of nitro group, which in turn reacted with several aromatic aldehydes and pyridinecarboxaldehydes as well as isocyanates to give a series of calix[4]pyrrole 10α,20α-disubstituted Schiff base and urea derivatives. The crystal structures of the newly-formed calix[4]pyrrole Schiff bases were successfully determined by X-ray diffraction. The complexing property of calix[4]pyrrole Schiff bases for transition metal ions was also investigated with UV–Vis spectroscopy.

A series of 5,5-dialkyl-10,10,20,20-tetraethyl-15-methyl-15-(4-nitrophenyl)calix[4]pyrroles were efficiently synthesized from acid catalyzed condensation of diethyldipyrromethanes with p-nitroacetophenone and further cyclization with other ketones. The corresponding calix[4]pyrrole mono-Schiff bases were obtained by sequential reductive hydrogenation of above 15-(4-nitrophenyl)calix[4]pyrroles and condensation with salicylaldehyde and pyridinecarboxaldehyde. Furthermore, the copper and zinc complexes of calix[4]pyrrole Schiff bases were successfully prepared and their crystal structures were also determined by X-ray diffraction.

A series of calix[4]pyrrole meso-substituted Schiff bases was synthesized with 5α,10α-di(4-hydroxylphenyl)calix[4]pyrrole or 5α,15β-di(4-hydroxylphenyl)calix[4]pyrrole as starting material. The synthetic routes included alkylation with methyl α-chlroroaceate, ammonolysis with alkylene diamine, and condensation with salicylladehyde or 2-hydroxynaphthaldehyde. The crystal structures of the new calix[4]pyrroles and their Schiff bases were determined by X-ray diffraction. The coordination properties of the representative calix[4]pyrrole Schiff bases to transition metal ions were also investigated by UV-Vis spectra.

The three-component reaction of triphenylphosphine, dialkyl but-2-ynedioate and arylidene pivaloylacetonitrile in dry methylene dichloride at room temperature resulted in unexpected densely substituted 1-(triphenyl-λ5-phosphanylidene)ethyl)-2,3-dihydrofurans in satisfactory yields with high diastereoselectivity. The relative configuration of the 2,3-dihydrofurans was elucidated by determination of single crystal structures.The three-component reaction of triphenylphosphine, dialkyl but-2-ynedioate and arylidene pivaloylacetonitrile in dry methylene dichloride at room temperature resulted in unexpected densely substituted 1-(triphenyl-λ5-phosphanylidene)ethyl)-2,3-dihydrofurans in satisfactory yields with high diastereoselectivity.

An efficient method for the synthesis of some difunctionalized copillar[5]arene Schiff bases from condensation of salicylaldehyde and its 5-chloro, 5-bromo, 3,5-di(t-butyl) substituted derivatives with corresponding diamino-functionalized copillar[5]arene, which were prepared by Gabriel reaction according to the reported method. Single-crystals of six copillar[5]arenes were determined by X-ray diffraction. An ORTEP of compounds showed that the two chains units of Schiff base exist in the outside of the cavity of pillar[5]arene. Furthermore, the complexing ability of these Schiff bases to transition metal ions were investigated by UV and fluorescence spectroscopy.A series of difunctionalized copillar[5]arene Schiff bases from the condensation of salicylaldehyde and its 5-chloro, 5-bromo, 3,5-di(t-butyl) substituted derivatives with corresponding di-amino-functionalized pillar[5]arenes were successfully prepared. The single crystal structures and coordination properties to some transition metal ions were investigated.

A new divergent intermolecular cascade annulation reaction of N-(arylsulfonyl)acrylamides with dual alkyl C(sp3)–H bonds for producing two types of five-membered rings, indanes and pyrrolidin-2-ones, is described. By using cycloalkanes and common alkanes as a one-carbon unit, an intermolecular [4+1] cascade carboannulation of N-(arylsulfonyl)acrylamides was achieved via a sequence of three C–H bond functionalization/aryl migration/desulfonylation that enables the formation of three C–C bonds and one N–H bond. When the one-carbon unit was changed to cycloalkyl ethers, the alternative intermolecular [4+1] cascade heteroannulation reaction occurred and allowed the construction of two C–C bonds and one C–N bond through dual C–H bond functionalization, aryl migration and desulfonylation cascades.