A facile solvent free Claisen-Schmidt reaction: synthesis of α,α'-bis-(substituted-benzylidene)cycloalkanones and α,α'-bis-(substituted-alkylidene)cycloalkanones.
Solvent-free Claisen-Schmidt reactions of cycloalkanones with various substituted benzaldehydes (aryl aldehydes) using solid NaOH (20 mol%) and applying a grinding technique were studied. Quantitative yields (96-98%) of α,α'-bis-(substituted-benzylidene)cycloalkanones were obtained. Aliphatic aldehydes also provided α,α'-bis-(substituted-alkylidene)cycloalkanones in very good yields with minor amounts of a-(substituted-alkylidene)cycloalkanones. The catalytic performance of solid NaOH was examined. The molar ratio of NaOH was optimized. The catalytic effect of solid NaOH was also evaluated by comparing it with KOH, NaOAc, and NH(4)OAc and it turns out that 20 mol% of solid NaOH was good enough to catalyze the Claisen-Schmidt reactions of cycloalkanones with various substituted benzaldehydes. Additionally, the regioselectivity of the Claisen-Schmidt reaction of acetone with benzaldehyde was examined. Using the same method, we could synthesize the corresponding bis-benzylidene- and mono-benzylideneacetone separately in 98% and 96% yields, respectively.
Department of Pharmaceutical Chemistry, College of Pharmacy, King Saud University, Riyadh11451, Saudi Arabia. afmrahman@ksu.edu.sa
A F M Motiur
AF
Rahman
Roushown
R
Ali
Yurngdong
Y
Jahng
Adnan A
AA
Kadi
D000085:Acetates; D001597:Benzylidene Compounds / Q000138:chemical synthesis* / Q000302:isolation & purification; D002384:Catalysis; D003516:Cycloparaffins / Q000138:chemical synthesis* / Q000302:isolation & purification; D005615:Freezing; D006878:Hydroxides / Q000737:chemistry; D017680:Potassium Compounds / Q000737:chemistry; D019346:Sodium Acetate / Q000737:chemistry; D012972:Sodium Hydroxide / Q000737:chemistry*; D060327:Solid-Phase Synthesis Techniques
D000085:Acetates; D001597:Benzylidene Compounds; D003516:Cycloparaffins; D006878:Hydroxides; D017680:Potassium Compounds; D019346:Sodium Acetate; D012972:Sodium Hydroxide; C018824:ammonium acetate; C029943:potassium hydroxide