Assiut university researches
Modern Friedel–Crafts Chemistry. Part 37.
Efficient Syntheses of Some New Julolidines
via Cyclialkylations of Heteroaryl Carbinols
Hassan A. K. Abd El-Aal, Ali A. Khalaf, and Ahmed M. A. El-Khawaga
Abstract:
A simple and convenient procedure for the synthesis of some
novel alkyl-substituted and aryl-substituted julolidines is
reported. Julolidines were smoothly synthesized in excellent
isolated yields via Friedel–Crafts intramolecular alkylations of
heteroarylalkanols in the presence of both Brønsted (PPA)
and Lewis (AlCl3/CH3NO2) acid catalysts. The precursors
alkanols, 1a–i, were readily prepared both by reaction of
selectively synthesized carboxylic acid esters and ketones
with different Grignard reagents and also by reduction of the
synthesized ketones with LAH. A plausible carbocation
mechanism is proposed to account for the results. The
structures of the compounds are established using both
spectral and analytical data.
Key words:
Friedel-Crafts cyclialkylations, julolidines, heteroaryl alkanols,
Brønsted and Lewis acid catalysts
Published in:
Journal of Heterocyclic Chemistry,Vol.51,PP.262-268