Diastereoselective Cascade Assembly of Functionalized Pyrano[3,4-c]pyrrole Derivatives

Synthesis of the first 4-oxobutane-1,1,2,2-tetracarbonitriles containing a phenol fragment and their transformation into cyano-substituted pyrrol-2-ones showing three-position molecular switching

The first example of the synthesis of 4-oxobutane-1,1,2,2-tetracarbonitriles (OTCs) containing a phenolic moiety has been described. The synthesis is based on the reaction between tetracyanoethylene and 4-hydroxyphenyl-substituted ketones under mild conditions. Due to the presence of a phenolic hydroxyl group, these compounds are more functionalized derivatives of the well-known OTC substrates used for diversity-oriented synthesis (DOS). The preserved synthetic potential of the OTCs for the preparation of phenol-containing derivatives with enhanced capabilities for tuning optical properties has been shown using the targeted synthesis of 2-(2-oxo-1,2-dihydro-3H-pyrrol-3-ylidene)malononitriles. Based on the obtained pyrroles and a model amine (pyrrolidine) a previously unknown type of thermosensitive three-position molecular switch is described. Reversible color changes of the dye are shown in both solution and on filter paper. The results reveal a new research branch of the OTC-based DOS strategy to access functionalized phenol-containing derivatives.

Molecular diversity of the base-promoted reaction of phenacylmalononitriles with dialkyl but-2-ynedioates

In the presence of tetrabutylammonium bromide (TBAB), the cycloaddition reaction of phenacylmalononitriles with dialkyl but-2-ynedioates in acetonitrile at room temperature resulted in 3,3-dicyano-5-hydroxy-5-arylcyclopent-1-ene-1,2-dicarboxylates in high yields. More importantly, the DABCO-promoted domino reaction of two molecules of each phenacylmalononitrile and dialkyl but-2-ynedioate in acetonitrile at room temperature afforded unique multifunctionalized carboxamide-bridged dicyclopentenes in moderate to good yields and with high diastereoselectivity.

Selective synthesis of multifunctionalized cyclopent-3-ene-1-carboxamides and 2-oxabicyclo[2.2.1]heptane derivatives

Triethylamine promoted cycloaddition reaction of phenacylmalononitrile with o-hydroxychalcones or chalcone o-enolates to selectively give cyclopent-3-ene-1-carboxamides and 2-oxabicyclo[2.2.1]heptanes.

Diastereoselective synthesis of 3,4-dihydro-2H-pyran-4-carboxamides through an unusual regiospecific quasi-hydrolysis of a cyano group

An efficient diastereoselective approach for the synthesis of functionalized 3,4-dihydro-2H-pyran-4-carboxamides with variable frame was developed based on the reaction of available 4-oxoalkane-1,1,2,2-tetracarbonitriles (adducts of TCNE and ketones) with aldehydes in an acidic media. An unusual process of quasi hydrolysis of the cyano group was observed in the course of the described regio- and diastereoselective transformation.

Synthesis and solid-state fluorescence of aryl substituted 2-halogenocinchomeronic dinitriles

Several novel aryl substituted 2-halogencinchomeronic dinitriles, possessing an intensive solid state fluorescence, were synthesized. The relationship between the chemical structures and photophysical properties of these compounds was investigated.