A new facile approach to the synthesis of 3-methylthio-substituted furans, pyrroles, thiophenes, and related derivatives.
2-(methylthio)-1,4-diaryl-2-butene-1,4-dione (3) are prepared from readily available aryl methyl ketones in the presence of copper(II) oxide, iodine, and dimethyl sulfoxide. The success of the cross-coupling reaction of 4-chloroacetophenone with 2-acetylthiophene confirms a proposed self-sorting tandem reaction mechanism. Both Z- and E-isomers of compound 3 are readily converted into the corresponding 3-methylthio 2,5-diaryl furan 7 in good yield through a domino process involving the reduction of the double bond followed by the Paal-Knorr furan synthesis. Meanwhile, 4-bromo-3-methylthio 2,5-diaryl furan 10 is obtained either by the treatment of furan 7 with molecular bromine or by the treatment of diketone 3 with 30% hydrogen bromide in acetic acid solution in one pot. Removal of the methylthio group is accomplished by the treatment of 7 with Raney Ni in ethanol, which affords the diaryl-substituted furan 11 in excellent isolated yield. Selective reduction of the double bond of compound 3 leads to the formation of the saturated 1,4-diketone 13, which is easily converted to the corresponding 3-methylthio-2,5-diaryl-substituted pyrrole 14 and thiophene 15 via the Paal-Knorr cyclization reaction.
Yin
Guodong
G
Key Laboratory of Pesticide & Chemical Biology, Ministry of Education, Central China Normal University, Wuhan 430079, People's Republic of China.
Wang
Zihua
Z
Chen
Aihua
A
Gao
Meng
M
Wu
Anxin
A
Pan
Yuanjiang
Y
D002851:Chromatography, High Pressure Liquid; D005663:Furans / Q000138:chemical synthesis* / Q000737:chemistry; D007659:Ketones / Q000737:chemistry; D013058:Mass Spectrometry; D008745:Methylation; D015394:Molecular Structure; D010084:Oxidation-Reduction; D011758:Pyrroles / Q000138:chemical synthesis* / Q000737:chemistry; D013438:Sulfhydryl Compounds / Q000737:chemistry*; D013876:Thiophenes / Q000138:chemical synthesis* / Q000737:chemistry
D005663:Furans; D007659:Ketones; D011758:Pyrroles; D013438:Sulfhydryl Compounds; D013876:Thiophenes; C039281:furan