An efficient and scalable synthesis of substituted phenanthrenequinones by intramolecular Friedel-Crafts reaction of imidazolides.
An efficient synthesis of 9,10-phenanthrenequinones is described. The two carbonyl groups were introduced by an orthoselective intermolecular Friedel-Crafts reaction of 3-methoxyphenol with ethyl chlorooxoacetate. The formation of a biaryl bond by Suzuki-Miyaura coupling reaction, followed by the hydrolysis of the ester, gave a biaryloxoacetic acid. Treatment of this acid with CDI gave the corresponding imidazolide. The ring closure to the desired phenanthrenequinone was accomplished by intramolecular Friedel-Crafts reaction of the imidazolide promoted by TiCl(4).
Yoshikawa
Naoki
N
Department of Process Research, Merck Research Laboratories, Merck & Co., Inc., Rahway, New Jersey 07065, USA. naoki_yoshikawa@merck.com
Doyle
Austin
A
Tan
Lushi
L
Murry
Jerry A
JA
Akao
Atsushi
A
Kawasaki
Masashi
M
Sato
Kimihiko
K
D002384:Catalysis; D020650:Combinatorial Chemistry Techniques; D007093:Imidazoles / Q000737:chemistry*; D015394:Molecular Structure; D010616:Phenanthrenes / Q000138:chemical synthesis* / Q000737:chemistry; D011809:Quinones / Q000138:chemical synthesis* / Q000737:chemistry
D007093:Imidazoles; D010616:Phenanthrenes; D011809:Quinones