Synthesis of 4,6‐Dimethyldibenzothiophene and 1,2,3,4‐Tetrahydro‐4,6‐dimethyldibenzothiophene via Tilak Annulation

Abstract

1,2,3,4-Tetrahydro-4,6-dimethyldibenzothiophene was prepared by coupling 2-bromo-3-methylcyclohexanone with 2-methylbenzenethiol and annulating the product with the aid of polyphosphoric acid. A mixture of 1,2,3,4-tetrahydro-4,6-dimethyldibenzothiophene and 4,6-dimethyldibenzothiophene was prepared by coupling 2-bromo-3-methylcyclohex-2-en-1-one with 2-methylbenzenethiol and annulating the product with the aid of polyphosphoric acid. 2-Bromo-3-methylcyclohexanone was synthesized by conjugate addition of Me 3 Al to 2-bromocyclohex-2-en-1-one with CuBr as catalyst and 2-bromo-3-methylcyclohex-2-en-1-one by brominationÀelimination of 3-methylcyclohex-2-en-1-one. 1,2,3,4,4a,9b-Hexahydro-4,6-dimethyldibenzothiophene was prepared by reduction of 1,2,3,4-tetrahydro-4,6-dimethyldibenzothiophene with Zn and CF 3 COOH.

Hydrodesulfurization of dibenzothiophene, 4,6-dimethyldibenzothiophene, and their hydrogenated intermediates over bulk tungsten phosphide

“…with 2-bromocyclohexanone instead of 2-chlorocyclohexanone in the first step. A mixture of 4,6-DMDBT and TH-4,6-DMDBT was prepared by coupling 2-bromo-3-methyl-2-cyclohexen-1-one with 2-methylbenzenethiol and annulating the product with the aid of polyphosphoric acid [16]. After separation by silica gel column chromatography, 4,6-DMDBT was obtained as white needle-like crystals and TH-4,6-DMDBT as a colorless liquid [16].…”

“…After separation by silica gel column chromatography, 4,6-DMDBT was obtained as white needle-like crystals and TH-4,6-DMDBT as a colorless liquid [16]. HH-DBT [17] and HH-4,6-DMDBT [16] were produced by hydrogenation of TH-DBT and TH-4,6-DMDBT, respectively, with zinc and trifluoroacetic acid at room temperature.…”

“…A mixture of 4,6-DMDBT and TH-4,6-DMDBT was prepared by coupling 2-bromo-3-methyl-2-cyclohexen-1-one with 2-methylbenzenethiol and annulating the product with the aid of polyphosphoric acid [16]. After separation by silica gel column chromatography, 4,6-DMDBT was obtained as white needle-like crystals and TH-4,6-DMDBT as a colorless liquid [16]. HH-DBT [17] and HH-4,6-DMDBT [16] were produced by hydrogenation of TH-DBT and TH-4,6-DMDBT, respectively, with zinc and trifluoroacetic acid at room temperature.…”