Synthesis of 5-Amino-3(2H)-furanones via S-Methylation/Intramolecular Cyclization of γ-Sulfanylamides.

The S-methylation/intramolecular cyclization of γ-sulfanylamide is depicted. Different methylating reagents were successfully employed for S-methylation, depending on the substituent pattern of the amide in the starting γ-sulfanylamides; trimethyloxonium tetrafluoroborate was used for N-aryl substituted γ-sulfanylamides, and the combination of methyl iodide and silver(I) tetrafluoroborate was used for N-alkyl substituted γ-sulfanylamides. When the resulting sulfonium salt was treated with DBU, it smoothly underwent intramolecular cyclization to produce a series of N-aryl, N-alkyl, N,N-dialkyl or N-alkyl-N-aryl substituted 5-amino-3(2H)-furanones in 55%-quantitative yields.

Synthesis of 5-Aryl-3(2 H)-furanones Using Intramolecular Cyclization of Sulfonium Salts.

Base-induced intramolecular cyclization of novel (4-aryl-2,4-dioxobutyl)methylphenylsulfonium salts prepared from the commercially available 1-arylethanone by a cost-effective process is described in this paper. The reaction was completed within 10 min to produce a family of 2-unsubstituted 5-aryl-3(2 H)-furanones in excellent yield. This procedure is simple, and can be carried out under mild conditions and an ambient atmosphere.

Synthesis of 4-Halo-3(2H)-furanones Using Intramolecular Cyclization of Sulfonium Salts.

A simple and efficient synthesis of 4-halo-3(2H)-furanones by halogenative intramolecular cyclization of sulfonium salts is described, which can expedite the production of a variety of 4-bromo- or 4-iodo-3(2H)-furanones, useful synthetic building blocks, in good to high yield under mild conditions.

Synthesis of Substituted 3(2H)-Furanones Using Alkylative Intramolecular Cyclization of Sulfonium Salts.

The facile alkylative intramolecular cyclization of 3-alkoxycarbonyl-2-oxopropyldiphenylsulfonium salts is described. This simple method can be readily applied to the synthesis of a novel family of 4-alkylated 3(2H)-furanones in moderate to high yields under mild conditions via a one-pot process.

Radical photocyclization route for macrocyclic lactone ring expansion and conversion to macrocyclic lactams and ketones.

A new method for the synthesis of macrocyclic lactones, lactams, and ketones, which utilizes photoinduced intramolecular radical cyclization reactions of substrates containing tethered carboxylic acids and α,ß-unsaturated carbonyl moieties, has been uncovered. Photocyclization of the carboxylic acids tethered acrylate ester, which were prepared starting from the macrocyclic lactones, gave the two-carbon elongated macrocyclic lactones via decarboxylation. Similar photoreactions of carboxylic acid tethered acryl amide or α,ß-unsaturated ketone moieties, which were also prepared starting from the macrocyclic lactones, produced macrocyclic lactams or ketones, respectively. The simple approach can be readily applied to the preparation of a variety of macrocyclic lactones, lactams, and ketones with tunable ring sizes.