Tandem one-pot synthesis of flavans by recyclable silica-HClO4 catalyzed Knoevenagel condensation and [4 + 2]-Diels-Alder cycloaddition.
An efficient one-pot multi-component synthesis of flavans using perchloric acid supported on silica as a recyclable heterogeneous catalyst has been described. This is the first report of direct one-step construction of a flavan skeleton from a phenolic precursor. The method involves a Knoevenagel-type condensation leading to in situ formation of transient O-quinone methide which further undergoes [4 + 2]-Diels-Alder cycloaddition with styrene to yield a flavan skeleton. The method provides easy access to a wide range of bio-active natural products viz. flavonoids, anthocyanins and catechins.
Medicinal Chemistry Division, Indian Institute of Integrative Medicine (CSIR), Canal Road, Jammu-180001, India. sbharate@iiim.ac.in
Sandip B
SB
Bharate
Ramesh
R
Mudududdla
Jaideep B
JB
Bharate
Narsaiah
N
Battini
Satyanarayana
S
Battula
Rammohan R
RR
Yadav
Baldev
B
Singh
Ram A
RA
Vishwakarma
D002384:Catalysis; D020650:Combinatorial Chemistry Techniques / Q000379:methods; D005419:Flavonoids / Q000138:chemical synthesis* / Q000737:chemistry; D045563:Indolequinones / Q000138:chemical synthesis / Q000737:chemistry; D010472:Perchlorates / Q000737:chemistry*; D012822:Silicon Dioxide / Q000737:chemistry*; D020058:Styrene / Q000138:chemical synthesis / Q000737:chemistry
D005419:Flavonoids; D045563:Indolequinones; D010472:Perchlorates; C068040:quinone methide; D020058:Styrene; D012822:Silicon Dioxide