Utilization of N-Acyl Compounds for the Synthesis of tricyclic and Bridged Heterocyclic Compounds
N-acyl derivative 4 was prepared via the reaction of methyl anthranilate with ethyl bromoacetate then refluxing the formed amino ester 3 with acetic anhydride. Cyclization of 4 in presences of sodium methoxide and methanol forming 2,4-pyrrolidindione derivative 5. 2,4-Quinolidinone 6 was obtained via cyclization of 4 in dry toluene and sodium hydride. On the other hand, indolinone derivative 9 was obtained by cyclization of 4 in toluene and free from alcohol due to retro Diekmann condensation. On treatment of 9 with sodium hydride, refluxing toluene and in presences of Crown ether gave tricyclic compound 10 which observed to exist in the enole form 11. Also, treatment of 2-pyrrolidinone with trimethylene chlorobromide produced 12 which cyclized using base and solvent to the bridged ring derivatives 13. The acidic hydrolysis of 13 afforded the corresponding amino acid 15. Whereas derivative 16 was obtained by the reaction of 2-pyrrolidinone with ethyl 3-bromopropionate which on cyclization gave azabicyclo[3,2,1]octan-4,8-dione derivative 17. Compound 17 underwent acidic hydrolysis to the amino ketone derivative azepanone hydrochloride 19.
Fawzia Z. El-Ablack, Mohamed A. Waly