InBr3-catalyzed stereoselective synthesis of 3,4-disubstituted hexahydro-1H-furo[3,4-c]pyran derivatives

An ?,δ-unsaturated alcohol tethered with a hydroxyl group, that is, (E)-2-styrylbutane-1,4-diol (1) undergoes a smooth bicyclization with various aldehydes in the presence of 10 mol % InBr₃ and at 0 °C to afford a novel series of hexahydro-1H-furo[3,4-c]pyran derivatives in good yields with high diastereoselectivity.     

Synthesis of structurally diverse diarylketones through the diarylmethyl sp CH oxidation

Under open-flask conditions, an efficient method to assemble a series of diversely functionalized diarylketones in the presence of commercially available NBS has been developed. Yields of up to 99% have been achieved employing diarylmethanes as starting material. Based on ¹⁸O-labeled experiment, the addition of stoichiometric water eventually leads to excellent yields in all carbonylation cases.     

Fluorogenic aldehydes bearing arylethynyl groups: turn-on aldol reaction sensors for evaluation of organocatalysis in DMSO

Fluorogenic aromatic aldehydes bearing arylethynyl groups were developed. They were used for monitoring the reaction progress of organocatalytic aldol reactions in DMSO through an increase in the fluorescence intensity based on the formation of the florescent aldol product. The ratios of the fluorescence intensities of the aldols to the aldehydes were more than 300. These results suggest that the fluorescence assay system using the aldehyde is useful for the rapid identification of superior aldol catalysts and reaction conditions.     

Copper(I) 3-methylsalicylate,an efficient catalyst for N-arylation of heterocycles under moderate reaction conditions

Copper(I) 3-methylsalicylate mediates N-arylation reactions of both aliphatic and aromatic heterocycles under moderate reaction conditions. Both electron rich and electron poor aryl bromides and a diverse set of N-heterocycles were allowed to react and gave N-arylation products in high yields which demonstrated the efficiency and utility of this catalyst.     

BF3·OEt2-catalyzed synthesis of 1-(tetrahydropyran-3-yl)-1,3-dihydroisobenzofuran and trans-fused hexahydropyrano[3,2-c]chromene derivatives

A novel intramolecular Prins cyclization of (E)-5-(2-(hydroxymethyl)phenyl)pent-4-en-1-ol with aldehydes has been achieved using 10 mol % BF₃·Et₂O to produce 1-(tetrahydropyran-3-yl)-1,3-dihydroisobenzofuran derivatives in good to excellent yields with high selectivity. Similar type of coupling with salicylaldehydes provides the trans-fused hexahydropyrano[3,2-c]chromene derivatives in excellent yields.     

Highly regioselective palladium-catalyzed direct alkenylation of thiazolo[3,2-b]-1,2,4-triazoles via CH activation

An efficient and regioselective palladium-catalyzed oxidative cross-coupling reaction between thiazolo[3,2-b]-1,2,4-triazoles and alkenes has been developed. This protocol provides easy access to a variety of functionalized thiazolo[3,2-b]-1,2,4-triazole derivatives.     

Operationally convenient method for preparation of sulfonamides containing α,α-difluoro-β-amino carbonyl moiety

We report here that the reactions of in situ generated unprotected α,α-difluoroenolates with various N-sulfonyl imines take place under operationally convenient conditions affording a novel type of fluorinated sulfonamides of high pharmaceutical potential. The reactions feature structural generality, excellent yields and can be easily scaled up for practical preparation of the target fluorine-containing sulfonamides.