β-Selective 2-Deoxy- and 2,6-Dideoxyglucosylations Catalyzed by Bis-Thioureas.

We present methods for β-selective 2-deoxy- and 2,6-dideoxyglucosylations of natural products, carbohydrates, and amino acids using bis-thiourea hydrogen-bond-donor catalysts. Disarming ester protecting groups were necessary to counter the high reactivity of 2-deoxyglycosyl electrophiles toward non-stereospecific S1 pathways. Alcohol and phenol nucleophiles with both base- and acid-sensitive functionalities were compatible with the catalytic protocol, enabling access to a wide array of 2-deoxy-β--glucosides.

Ketones from Nickel-Catalyzed Decarboxylative, Non-Symmetric Cross-Electrophile Coupling of Carboxylic Acid Esters.

Synthesis of the C-C bonds of ketones relies upon one high-availability reagent (carboxylic acids) and one low-availability reagent (organometallic reagents or alkyl iodides). We demonstrate here a ketone synthesis that couples two different carboxylic acid esters, N-hydroxyphthalimide esters and S-2-pyridyl thioesters, to form aryl alkyl and dialkyl ketones in high yields. The keys to this approach are the use of a nickel catalyst with an electron-poor bipyridine or terpyridine ligand, a THF/DMA mixed solvent system, and ZnCl to enhance the reactivity of the NHP ester.