Thiourea mediates cooperative glycosidation through hydrogen bonding. N,N'-Diarylthiourea as cocatalyst enforces an SN2-type acid-catalyzed glycosidation even at room temperature (see scheme; Bn=benzyl). From O-(α-glycosyl) trichloroacetimidates as glycosyl donors and various acceptors, β-glycosides are preferentially or exclusively obtained.

The combination of PPh3/I2 has been shown to be effective for conversion of a range of carboxylic acids to 2°, 3°, and Weinreb amides. Simplification of the procedure was possible with the use of polymer-supported PPh3/I2. Weinreb amides produced via the use of polymer-supported PPh3 could be filtered through a short silica gel plug and used in further transformations. Thus, use of polymer-supported PPh3 offers potential applicability to diversity-oriented reactions. Formal total syntheses of apocynin and pratosine, as well as syntheses of anhydrolychorinone and hippadine, have been achieved via the use of this amide-forming method. An attempt has been made to gain insight into this reaction.

The glycosylation of O-glycosyl trichloroacetimidate donors using a synergistic catalytic system of electron-deficient pyridinium salts/aryl thiourea derivatives at room temperature is demonstrated. The acidity of the adduct formed by the 1,2-addition of alcohol to the electron-deficient pyridinium salt is increased in the presence of an aryl thiourea derivative as an hydrogen-bonding cocatalyst. This transformation occurs under mild reaction conditions with a wide range of O-glycosyl trichloroacetimidate donors and glycosyl acceptors to afford the corresponding O-glycosides in moderate to good yields with predictable selectivity. In addition, the optimized method is also utilized for the regioselective O-glycosylation by using a partially protected acceptor.

Adduct formation between alcohols as glycosyl acceptors and phenylsilicon trifluoride (PhSiF3) as catalyst permits acid‐base‐atalyzed glycosidations with O‐glycosyl trichloroacetimidates as glycosyl donors. In this way, from various glycosyl donors and acceptors 1,2‐trans‐ and some 1,2‐cis‐glycosides could be obtained with high anomeric selectivity. A preference for an intramolecular bimolecular nucleophilic substitution (SN2‐type) reaction course with concomitant donor and acceptor activation is supported by the results.

An efficient and operationally simple gold­(III)-catalyzed glycosylation protocol was developed using newly synthesized benchtop stable phenylpropiolate glycosyl (PPG) donors. Gold­(III)-catalyzed activation of PPGs proceeds well with various carbohydrate and noncarbohydrate-based glycosyl acceptors and leads to their corresponding O/N-glycosides in good to excellent yields with regeneration of reusable and easily separable phenylpropiolic acid. Differentially protected PPGs reacted well under the optimized reaction conditions. In particular, good anomeric selectivity was observed with mannosyl and rhamnosyl PPG donors. A preliminary mechanistic study reveals that the presence of a triple bond adjacent to the ester group is essential for activation, and PPG-based donor shows higher reactivity than analogous acetate and benzoate donors.

Chloroamidation of olefins using a new reagent system (COCl)2-AgNO3-CH3CN was observed. Various glycals with this reagent system produce 2-chloro-1-acetamido sugars in good yields which, in turn, were converted to free amino derivatives and various glycopeptides. The acetamido sugar derivatives and free amines were found to be promising anticancer agents against the U-87 malignant glyoma (a brain tumor) cell line with IC-50=1 nm-22 microM, and they were found to be far less cytotoxic against a normal human embryonic kidney cell line.

An efficient and regioselective palladium(II)-catalyzed primary acetamide assisted ortho arylation of arylacetamide has been discovered. This is the first report where functionalizable primary acetamide (-CHCONH) is used as a directing group for C(sp)-H activation/cross-coupling reactions, circumventing the extra steps of installation and subsequent removal of the directing groups. The synthetic utility of this transformation is demonstrated through the scale-up synthesis. In addition, the primary acetamide can be manipulated into synthetically important derivatives such as nitriles and carboxylic acids.

Boron trifluoride or trimethylsilyl trifluoromethanesulfonate catalysed the generation of thioglycosides from O‐glucopyranosyl or O‐galactopyranosyl trichloroacetimidates and thiols giving mainly or exclusively α‐thioglycosides. However, the same reactions with phenylboron difluoride as catalyst are highly β‐selective. An SN2‐type reaction course under acid/base catalysis is invoked by these and previous results.