Investigation of the regioselectivity of the Hurd–Mori reaction for the formation of bicyclic 1,2,3-thiadiazoles

Copper-Catalyzed Coupling of Thioamides and Donor/Acceptor-Substituted Carbenoids: Synthesis of Enamino Esters and Enaminones

The coupling of thioamides and donor/acceptor-substituted diazocarbonyl compounds is reported for the first time. The present report provides a mild, catalytic method that couples thioamides and donor/acceptor-substituted diazocarbonyl compounds to form enamino esters and enaminones. Unlike traditional methods for the synthesis of enamino esters and enaminones from thioamides, both N-alkyl thioamides and thiocarbamates are suitable substrates in this coupling reaction. Copper(I) bromide catalyzes the reaction and provides enamino esters and enaminones chemo- and diastereoselectively in less time than Rh2(OAc)4 or Ru(PPh3)3Cl2 catalysts.

Preparation of chiral 3-oxocycloalkanecarbonitrile and its derivatives by crystallization-induced diastereomer transformation of ketals with chiral 1,2-diphenylethane-1,2-diol

Chiral 3-oxocycloalkanecarbonitriles were prepared by fractional crystallization and crystallization-induced diastereomer transformation (CIDT) of diastereomeric ketals with (1R,2R)-1,2-diphenylethane-1,2-diol. Investigation of the crystal structures by X-ray diffraction analysis revealed that the difference in hydrogen bonds caused the discrepancy of the solubilities between (R) and (S) diastereomers. Furthermore, CIDT to afford the (R)-diastereomer in good yield (95% yield) and with high diastereoselectivity (97% de) was accomplished, which is the first example of CIDT of neutral compounds via formation of the diastereomeric ketal with (1R,2R)-1,2-diphenylethane-1,2-diol.

Chiral 3-oxocyclopentanecarbonitrile was prepared in good yield and with high diastereoselectivity by crystallization-induced diastereomer transformation of the corresponding diastereomeric ketal.