Guodong Yin

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.

Stereoselective Synthesis of 2,8-Dioxabicyclo[3.3.1]nonane Derivatives via a Sequential Michael Addition/Bicyclization Reaction

A highly efficient and stereoselective synthesis of coumarin-, 1,3-cyclohexanedione-, and 1,4-naphthoquinone-fused 2,8-dioxabicyclo[3.3.1]nonanes is described. This was achieved via a sequential Michael addition/bicyclization reaction from easily accessible 3-(2-hydroxyphenyl)-1-phenylprop-2-en-1-one derivatives. Three chemical bonds (one C-C bond and two C-O bonds), two six-membered cycles, and two stereogenic centers were formed in a one-pot operation.

Highly efficient synthesis of 3a,6a-dihydrofuro[2,3-b]furans via a novel bicyclization.

A highly efficient method for the construction of 3a,6a-dihydrofuro[2,3-b]furan derivatives has been developed via a novel bicyclization, which is very valuable for the synthesis of fused furofuran compounds since it is time-saving and catalyst-free. Based on the bicyclization, a coupled domino strategy has been developed to directly construct 3a,6a-dihydrofuro[2,3-b]furan derivatives from methyl ketones.

Clean and efficient assembly of functionalized benzofuro[2,3-c]pyridines via metal-free one-pot domino reactions

A clean and efficient method for the domino synthesis of new functionalized benzofuro[2,3-c]pyridines from easily accessible 2-hydroxychalcones, α-bromo ketones and ammonium acetate is described. Furan and pyridine ring moieties are ingeniously formed in a one-pot operation in this tricyclic system.

Efficient Selective Formation of C‐C Single Bonds and C˭C Double Bonds by NBS‐Promoted Oxidative Coupling of β‐Keto Esters

Abstract A new application of NBS, which results in the oxidative coupling of β‐keto esters to selectively form C‐C single and C˭C double bonds, can be controlled by the amount of NBS and t‐BuOK employed. This methodology adds a new entry to C‐C single and C˭C double‐bond formation between active methylene groups under mild conditions with high selectivity.

Diethyl 2,6-dicyclo­hexyl-4,8-dioxo-2,2,3,6,7-tetra­hydro-1H,5H-2,3a,4a,6,7a,8a-hexa­azacyclo­penta­[def]fluorene-8b,8c-dicarboxyl­ate

In the title compound, C26H40N6O6, the five-membered rings adopt envelope conformations and the six-membered rings are in chair conformations. The crystal packing is stabilized by C—H⋯O hydrogen bonds.