Diboronate Fluorophore for the Measurement of l-Glucose and Other Carbohydrates and Its Interaction with Albumin.

l-Glucose has recently been investigated as an artificial sweetener, but no facile method is established for the measurement of l-glucose. The commercial probe Eversense employs a fluorescent diboronate in a small device for the optical monitoring of d-glucose in people with diabetes. Being achiral, the Eversense probe should be able to detect l-glucose as well as native d-glucose, but the probe is designed for fixation under the skin, and our attempts to use the probe at laboratory conditions failed, as the probe was resetting when moved between compartments. We thus designed a water-soluble anthracene diboronate 8 similar to the fluorophore used in Eversense and found 8 to respond well to l-glucose and other carbohydrates and artificial sweeteners, thus enabling measurements of l-glucose with the limit of quantification of 12 µM. Notably, the fluorescent signal of diboronate 8 was largely quenched in buffers with the physiological concentration of albumin (0.5 mM), so the given analytical method would need more optimization to be useful for measuring l-glucose and other carbohydrates in blood samples. We suspect that other diboronate fluorophores from the literature may be similarly quenched if applied in the presence of albumin.

Distal Weak Coordination of Acetamides in Ruthenium(II)-Catalyzed C-H Activation Processes.

C-H activations with challenging arylacetamides were accomplished by versatile ruthenium(II) biscarboxylate catalysis. The distal C-H functionalization offers ample scope-including twofold oxidative C-H functionalizations and alkyne hydroarylations-through facile base-assisted internal electrophilic-type substitution (BIES) C-H ruthenation by weak O-coordination.

Modular and highly stereoselective approach to all-carbon tetrasubstituted alkenes.

A modular and completely stereoselective approach for the construction of all-carbon tetrasubstituted alkenes is described. It is based on the three-fold, sequential metal-catalyzed, cross-coupling functionalization of simple enolphosphate dibromide templates with carbon nucleophiles, affording tetrasubstituted alkenes as single isomers.

Selective synthesis of 7-substituted purines via 7,8-dihydropurines.

A simple and efficient protocol for the preparation of 7-substituted purines is described. 6- and 2,6-Dihalopurines were N(9)-tritylated and then transformed to 7,8-dihydropurines by DIBAL-H. Subsequent N(7)-alkylation followed by N(9)-trityl deprotection with trifluoroacetic acid was accompanied by spontaneous reoxidation, which led to the 7-substituted purines at 55-88% overall isolated yields.