An important and surprising finding that the acetalization and ketalization of aldehydes and ketones with alcohols, respectively, proceed smoothly in the presence of 0.1 mol % acid, without removing water, has been presented. This process has many merits, such as commercial available catalysts with low cost and low loadings (as low as 0.03 mol %), quite a broad substrate scope (including various aldehydes, ketones, acid-sensitive substrates, and diols), a wide range of reaction temperature (−60 to 50 °C), high yields, large-scale preparation, environmental friendliness, and simple work-up procedure. This new protocol has also been successfully applied to protect the important organic compounds, such as 1,3-diols, 1,2-diols, acid-sensitive substrates, glucose, and 1,3-dicarbonyl compounds.

We developed an enantioselective organocascade Michael/Henry reaction in the presence of a bifunctional organocatalyst to construct chiral polyfunctionalized 3,4-dihydro-2H-thiopyrano[2,3-b]quinolines. The resulting optically active products with three contiguous stereocenters, one quaternary and two tertiary, were obtained in moderate to good yields and with good to excellent enantioselectivities. Remarkably, the resulting products were readily converted into polyfunctionalized optically active furo[2′,3′:4,5]thiopyrano[2,3-b]quinoline, 3,4-dihydro-2H-thiopyrano[2,3-b]quinoline 1-oxide and 2,3-dihydro-4H-thiopyrano[2,3-b]quinolin-4-one derivatives.

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An efficient, mild, and substrate/catalyst-controlled chemoselective reaction of o-isothiocyanato-(E)-cinnamaldehyde with amines has been established, producing three types of six-membered heterocycles: 2-(4H-benzo[d][1,3]thiazin-4-yl)acetaldehydes, 2-(2-thioxo-1,2,3,4-tetrahydroquinazolin-4-yl)acetaldehydes, and (E)-4-(2-methoxyvinyl)-4H-benzo[d][1,3]thiazines. The reaction scopes were quite broad and excellent yield was achieved. This method is extremely efficient and practical and can be conducted on a gram-scale with slightly inferior reactivity under catalyst-free conditions at low cost, making it an ideal alternative to existing methods.

A one-pot synthesis of substituted (dihydro)thieno[2,3-c]chromene derivatives was developed through a Lewis base catalyzed domino Michael addition/intramolecular cyclization reaction between 3-nitro-2H-chromenes and thioamides. The desired (dihydro)thieno[2,3-c]chromene derivatives were prepared with a large substrate scope (22 examples) and excellent diastereoselectivity in moderate to excellent yields.