Synthesis of 3-Hydroxy-2,3-dihydro-1H-isoindole-1-thione Derivatives by the Reaction of 2,N-Dilithiobenzamides with Carboxylic Esters
摘要:
An efficient one-pot method for the preparation of 2,3-disubstituted 3-hydroxy-2,3-dihydro-1H-isoindole-1-thiones from secondary benzothioamides and carboxylic esters has been developed. Thus, the reaction of the starting thioamides with two equivalents of butyllithium generates the corresponding 2,N-dilithiobenzothioamides, which are then allowed to react with carboxylic esters to give the desired products. The similar preparation of 4- and 5-aza-analogues from 2(or 3)-bromopyridine-3(or 4)-carbothioamides, respectively, is also described.
The reaction of 2,N-dilithiobenzothioamides, generated from readily available secondary benzothioamides and two equivalents of butyllithium, with isothiocyanates, followed by aqueous workup, gives the corresponding N-1,N-2-disubstituted benzene-1,2-dicarbothioamides, which undergo intramolecular attack of one of the thioamide nitrogen on the adjacent thiocarbonyl moiety with loss of primary amines to provide 2-substituted 1H-isoindole-1,3(2H)-dithiones.
FARINA C.; PELLEGATA R.; PINZA M.; PIFFERI G., ARCH. PHARM., 1981, 314, NO 2, 108-117