Asian Journal of Chemistry; Vol. 29, No. 4 (2017), 755-757
A
SIAN
J
OURNAL OF HEMISTRY
C
Reaction of Cyano Active Methylene Compounds with
2-Hydroxy-1-naphthal-4-acetylaniline: An Unexpected Result
*
RAMANDEEP KAUR MEHTON and M.R. MANRAO
Department of Chemistry, Punjab Agricultural University, Ludhiana-141 004, India
*Corresponding author: E-mail: ramanmehton@gmail.com
Received: 5 August 2016; Accepted: 7 January 2017;
Published online: 31 January 2017;
AJC-18238
Condensation of cyano active methylene compounds (1-5) with 2-hydroxy-1-naphthal-4-acetylaniline, the compound containing both
carbon-nitrogen double bond as well as carbon-oxygen double bond, in equimolar ratio resulted in the formation of crude solids (1a-5a)
which were crystallized from benzene. The products were characterized as 3-imino-3H-benzo[f]chromene derivatives (1a-5a) on the
basis of elemental analysis and spectral studies. Reaction of compounds (1-5) with 2-hydroxy-1-naphthal-4-acetylaniline in 2:1 molar
ratio also yielded the same products (1a-5a). Thus, cyano active methylene compounds reacted chemoselectively with carbon-nitrogen
double bond of 2-hydroxy-1-naphthal-4-acetylaniline, leaving the carbon-oxygen double bond, considered to be more reactive, intact,
leading to the formation of mono addition-elimination products which cyclized due to interaction between hydroxyl group and cyano group.
Keywords: Cyanoacetic acid, Malononitrile, 2-Hydroxy-1-naphthal-4-acetylaniline, 3-Imino-3H-benzo[f]chromene derivatives.
Mass spectra were recorded on Perkin Elmer Clarus 500 mass
spectrometer.
INTRODUCTION
The chemistry of multiple bonds has achieved a dramatic
development in recent decades [1,2], because these compounds
have been utilized as substrates in the synthesis of industrial
[3] and bioactive compounds [4]. The carbon-nitrogen double
bond is intermediate in reactivity [5] between carbon-oxygen
and carbon-carbon double bonds. Reaction of active methylene
compounds with carbonyl compounds yields condensation
products [6] whereas such a reaction with imines, the com-
pounds containing carbon-nitrogen double bond, results in the
formation of either adducts [7] or addition-elimination products
[8] depending on the nature of active methylene compound
and reaction conditions. The present work was aimed to study
the reaction of active methylene compounds containing at least
one cyano group with 2-hydroxy-1-naphthal-4-acetylaniline,
the compound containing both carbon-nitrogen double bond
as well as carbon-oxygen double bond and the unexpected
results of this work are being presented in this communication.
Synthesis of 2-hydroxy-1-naphthal-4-acetylaniline: A
mixture of 2-hydroxy-1-naphthaldehyde (0.01 mol), dry ethanol
(20 mL) and 4-acetylaniline (0.01 mol) was refluxed in a flask
(150 mL) using a ‘Dean and Stark’water separator. The solu-
tion was then allowed to cool and the separated solid was
filtered and purified by recrystallization from ethanol to get
shinning crystals of 2-hydroxy-1-naphthal-4-acetylaniline,
m.p. 155°C, yield 96 %.
General procedure for the reaction of cyano active
methylene compounds with 2-hydroxy-1-naphthal-4-acetyl-
aniline: 2-Hydroxy-1-naphthal-4-acetylaniline (0.01 mol) was
taken in dry benzene (20 mL) in a conical flask (100 mL).
Then active methylene compound (1-5) (0.01 mol) and a few
drops of pyridine were added to the above solution. The
reaction mixture was heated and shaken briskly for 30-45 min.
The contents were then cooled, the flask was stoppered and
allowed to stand at room temperature for overnight. The crude
solid which separated out was filtered and recrystallized from
benzene to get respective 3-imino-3H-benzo[f]chromene
derivative (1a-5a). Evaporation of the solvent from the filterate
yielded jelly like mass, TLC of which indicated the presence
of 4-acetylaniline and unreacted starting materials.
EXPERIMENTAL
The purity of the compounds was checked by TLC. The
melting points were recorded on electrical melting point
apparatus and are uncorrected. The IR spectra were recorded
on a Perkin Elmer FT-IR spectrometer using KBr disc. The 1H
NMR spectra were recorded on a Brucker Spectrospin 300
MHz spectrometer in CDCl3 with TMS as internal standard.
Reaction of one mole of 2-hydroxy-1-naphthal-4-acetylaniline
with two moles of cyano active methylene compounds (1-5) was
also carried out by following the above procedure (Scheme-I).