Categories: Synthesis of O-Heterocycles >
Synthesis of Coumarins
Name Reactions
Recent Literature
Palladium-catalyzed oxidative Heck coupling reaction of coumarins and
arylboronic acids allows a direct synthesis of 4-arylcoumarins in good yields.
The reaction also showed tolerance toward functional groups such as hydro,
methoxy, diethylamino, nitro, and chloro groups.
Y. Li, Z. Qi, H. Wang, X. Fu, C. Duan, J. Org. Chem., 2012,
77, 2053-2057.
The employment of hydrophobic ionic liquids
dramatically enhanced the activity of metal triflates in Friedel-Crafts
alkenylations of aromatic compounds with various alkyl- and aryl-substituted
alkynes.
C. E. Song, D.-U. Jung, S. Y. Choung, E. J. Roh, S.-G. Lee, Angew. Chem., 2004, 116,
6309-6311.
Arylpropionic acid methyl esters having a MOM-protected
hydroxy group at the ortho position underwent hydroarylation with various
arylboronic acids in MeOH at ambient temperature in the presence of a catalytic
amount of CuOAc, resulting in the formation of
4-arylcoumarins in high yields after the acidic workup.
Y. Yamamoto, N. Kirai, Org. Lett., 2008,
10, 5513-5516.
The use of cyanuric chloride (2,4,6-trichloro-1,3,5-triazine) and N-methyl
morpholine enables an efficient and general protocol for a rapid synthesis of
substituted 3-aryl coumarins. A series of substituted phenyl acetic acids have
been successfully reacted with substituted 2-hydroxy benzaldehydes to afford
3-aryl coumarins in good to excellent yields.
K. V. Sashidhara, G. R. Palnati, S. R. Avula, A. Kumar, Synlett, 2012,
611-621.
The basic ionic liquid 1-butyl-3-methylimidazolium hydroxide, [bmIm]OH,
efficiently catalyzes the Knoevenagel condensation of various aliphatic and
aromatic aldehydes and
ketones with active methylenes at room temperature without requirement of any
organic solvent.
B. C. Ranu, R. Jana, Eur. J. Org. Chem., 2006, 3767-3770.
A facile, convenient, efficient, and high yielding synthesis of a
combinatorial library of 3-aroylcoumarins has been developed by the
condensation of easily available -aroylketene dithioacetals and
2-hydroxybenzaldehydes in the presence of catalytic amount of piperidine in
THF reflux.
H. S. P. Rao, S. Sivakumar, J. Org. Chem., 2006, 71, 8715-8723.
The ionic liquid 1-butyl-3-methylimidazonium tetrafluoroborate [bmim]BF4
was used for ethylenediammonium diacetate (EDDA)-catalyzed Knoevenagel
condensation between aldehydes or ketones with active methylene compounds.
Catalyst and solvent can be recycled.
C. Su, Z.-C. Chen, Q.-G. Zhen, Synthesis, 2003, 555-559.
4-Carboxyalkyl-8-formyl coumarins can be synthesized from
2-hydroxybenzaldehydes, triphenylphosphine and dialkyl acetylenedicarboxylate in
good yields via vinyltriphenylphosphonium salt mediated aromatic electrophilic
substitution.
K. C. Majumdar, I. Ansary, S. Samanta, B. Roy, Synlett, 2011,
694-698.
A new carbamoyl Baker-Venkataraman rearrangement allows a general synthesis of
substituted 4-hydroxycoumarins in good overall yields. Intermediate arylketones
are efficiently prepared via a Directed ortho Metalation - Negishi cross
coupling protocol from arylcarbamates. The overall sequence provides a
regiospecific anionic Friedel-Crafts complement for the construction of ortho-acyl
phenols and coumarins.
A. V. Kalinin, A. J. M. Da Silva, C. C. Lopes, R. S. C. Lopes, V. Snieckus,
Tetrahedron. Lett., 1998, 39, 4995-4998.
