80633-41-6Relevant academic research and scientific papers
Reaction of Ketenes with N,N-Disubstituted α-Aminomethyleneketones. XI. Synthesis of 2H-Pyranobenzothiazole Derivatives
Mosti, Luisa,Menozzi, Giulia,Schenone, Pietro
, p. 1263 - 1267 (2007/10/02)
Cycloaddition of dichloroketene to N,N-disubstituted 6-aminomethylene-5,6-dihydro-2-phenylbenzothiazol-7-(4H)ones gave in good yield N,N-disubstituted 4-amino-3,3-dichloro-3,4,5,6-tetrahydro-8-phenyl-2H-pyranobenzothiazol-2-ones II, which are derivatives of the new heterocyclic system 2H-pyranobenzothiazole.Dehydrochlorination with triethylamine of II afforded N,N-disubstituted 4-amino-3-chloro-5,6-dihydro-8-phenyl-2H-pyranobenzothiazol-2-ones III in good to moderate yield.The dimethylamino adduct was dehydrochlorinated in high yield by refluxing in toluene, whereas the diisopropylamino adduct gav e in low yield 6-(2,2-dichloroethylidene)-5,6-dihydro-2-phenylbenzothiazol-7-(4H)one with the triethylamine treatment.The dehydrochlorinated product IIId (NR2 = pyrrolidino) was obtained directly in low yield by cycloaddition of dichloroketene to the corresponding enaminone.Full aromatisation of IIIa,g 2 = N(CH3)2 and N(CH3)C6H5, respectively) to the corresponding N,N-disubstituted 4-amino-3-chloro-8-phenyl-2H-pyranobenzothiazol-2-ones was accomplished with DDQ in refluxing benzene.
