A convenient approach to an advanced intermediate toward the naturally occurring, bioactive 6-substituted 5-hydroxy-4-aryl-1H-quinolin-2-ones
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Royal Society of Chemistry
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5-Hydroxy-4-aryl-3,4-dihydro-1H-quinolin-2-ones are a small family of natural products isolated from
fungal strains of Penicillium and Aspergillus. Most of its members, which are insecticides and anthelmintics,
carry an isoprenoid C-6 side chain. The synthesis of a 6-propenyl-substituted advanced intermediate
for the total synthesis of these natural products is presented in this paper. This was achieved through the
stereoselective construction of a β,β-diarylacrylate derivative from 6-nitrosalicylaldehyde, using a Wittig
olefination and a Heck–Matsuda arylation, followed by a selective Fe0-mediated reductive cyclization.
Installation of the 6-propenyl side chain was performed by 5-O-allylation of the heterocycle, followed by
Claisen rearrangement and conjugative migration of the allyl double bond, as the key steps. The Grubbs
II-catalyzed olefin cross metathesis of the 6-allyl moiety with 2-methylbut-2-ene to afford a precursor of
peniprequinolone is also reported.