ORGANOPHOSPHORUS COMPOUNDS ACTION OF 2,4-BIS-(4-METHOXYPHENYL)-1,3,2,4-DITHIAPHOSPHETANE-2,4-DISULFIDE (LAWESSON REAGENT) AND 2,4-BIS-(PHENYLTHIO)-1,3-DITHIA-2,4-DIPHOSPHETANE-2,4-DISULFIDE (JAPANESE REAGENT) ON FLAVONE, α-NAPHTHOFLAVONE AND β-NAPHTHOFLAVONE

Abstract

Japanese reagent JR, 1b converts 2-phenyl-(5,6-Benz)-y-pyrone (flavone, 2a) into 2-phenyl-5,6-benzpyrane-4-thione 2b. Lawesson reagent LR, 1a converts 2-phenyl-7,8-benzo-1,4-chromone (α-naphthoflavone, 3a) and 2-phenyl-5,6-benzo-1,4-chromone (β-naphthoflavone 4a) into their corresponding thioketones 3b and 4b respectively. Thiation of 3a and 4a with Lawesson reagent, 1a can be induced photochemically to give 3b and 4b. Thiation of a-naphthoflavone 3a and β-naphthoflavone 4a with Japanese reagent JR, 1b is accompanied with ring opening at the heterocyclic oxygen atom of the γ-pyrone ring to yield products 5 and 6 respectively. The given structures were based upon analytical, chemical and spectroscopic results.

Key Words:

• Lawesson reagent
• Japanese reagent
• Thiation
• γ-pyrones.