作者:J. C. Jochims、C. Troll、H. Fischer、Q. Wang、A. Hamed、A. El-Hamid Ismail、M. Taha Abdel-Aal、I. Zeid、M. Al-Talib
DOI:10.1002/prac.19923340805
日期:——
Trichlormethanes 4 react with two equivalents of n-alkyl isocyanates R2-NCO in the presence of SbCl5 to furnish the 2,2-dichloro-5,6-dihydro-6-oxo-2H-1,3,5-oxadiazinium salts (9). The structure of these heterocycles is confirmed by an X-ray analysis of 9d (R1 = ClC = CCl2, R2 = Et). p-Tolyl isocyanate is Friedel-Crafts alkylated by 4b in the presence of SbCl5. Subsequent ring closure affords the quinolinium salt 13, which is hydrolyzed to give inter alia the quinolone 16.