Synthesis of 2,5-asymmetrically substituted 3,4-diaminothieno[2,3-b]thiophenes by domino reaction.

A convenient one pot synthesis of 2,5-asymmetrically substituted thieno[2,3-b]thiophenes is developed. The method is based on consecutive domino reactions (SN2 reaction → Thorpe-Ziegler reaction) using malononitrile and carbon disulfide as starting materials with the generation of potassium 2,2-dicyanoethene-1,1-bis(thiolate) in a solution. The high yield of the target thienothiophenes was achieved using the Ziegler dilution effect.

Synthesis of isomeric isothiazolo[4',3':4,5]- and isothiazolo[4',5':4,5]thieno[3,2-b]pyrano[2,3-d]pyridines by combination of domino reactions.

Isothiazolothienopyridines have been prepared by a domino reaction (the SN2 reaction → the Thorpe-Ziegler reaction → the Thorpe-Guareschi reaction type) from disodium 4-cyanoisothiazole-3,5-dithiolate. By changing the order of addition of the alkylation reagents in the reaction with disodium 4-cyanoisothiazole-3,5-dithiolate both possible isomers of the isothiazolothienopyridines are synthesized. These isomers were further used in three-component domino reaction (the Knoevenagel reaction → the Michael reaction → the hetero-Thorpe-Ziegler reaction type) to obtain wide range of isomeric isothiazolothienopyranopyridines.

Versatile three-component procedure for combinatorial synthesis of 2-aminospiro[(3'H)-indol-3',4-(4H)-pyrans].

A convenient method of synthesis of substituted and annulated 2-amino-spiro[(3' H)-indol-3',4-(4 H)-pyrans] at mild conditions and in good yields is developed. Three component reaction of wide variety of substituted isatins, cyanoacetic acid derivatives, and carbonyl compounds or phenols gives the target compounds. Forty new spiropyrans were obtained, and their structures were proved by elemental analysis and 1H NMR and IR spectral data. It is shown that the use of a not very large set of starting compounds can lead to the synthesis of a thousand-member 2-amino-spiro[(3' H)-indol-3',4-(4 H)-pyran] library.