Palladium-catalyzed carboxylative cyclization of propargylic amines with aryl iodides, CO2 and CO under ambient pressure.

A palladium-catalyzed four-component carboxylative cyclization comprising propargylic amines, aryl iodides, CO2 and CO was developed. By selecting Et3N and 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) as the base, respectively, both terminal and internal propargylic amines proceeded well facilitated by Pd(PPh3)2Cl2, affording the functionalized 2-oxazolones in moderate yields. This protocol enlarges the product diversity based on CO2 conversion and simultaneously provides a cooperative transformation route for both CO2 and CO.

Visible light-driven carbamoyloxylation of the α-C(sp3)-H bond of arylacetones via radical-initiated hydrogen atom transfer.

Photocatalytic synthesis has emerged as an efficient route to transform CO2 into functionalized organic carbamates by photocatalysis. Herein, a catalyst-free carbamoyloxylation of arylacetones with CO2 and amines under visible light was developed for the synthesis of O-ß-oxoalkyl carbamates in yields up to 93%. This protocol proceeded smoothly with the assistance of inexpensive carbon tetrabromide at room temperature under atmospheric CO2 pressure, leading to simultaneous construction of C-O and C-N bonds. Mechanism studies suggested the photoinduced hydrogen atom transfer (HAT) pathway followed by radical addition or single electron transfer (SET).

Green Tailoring With Water of Choline Chloride Deep Eutectic Solvents for the Extraction of Polyphenols From Palm Samples.

To address the problem of high viscosity of deep eutectic solvents (DESs), the viscosities of a series of choline chloride-based DESs and DESs-H2O were determined, and their extraction efficiencies were obtained for the extraction of polyphenols in palm samples. Tailoring the DESs by the addition of water successfully adjusted their viscosity from thousand to single-digit mPa s and aided the extraction of polyphenols from samples, by changing the hydrogen-bonding interactions of DESs. Among the compounds investigated, choline chloride-oxalic acid-water of DESs-H2O with various molar ratios with 1:0.1-1:50 showed the greatest change in viscosity with 3617-2 mPa s, and effectively extracted most of the target compounds of polyphenols (52.1 µg mL-1 for protocatechuic acid, 7.3 µg mL-1 for catechins, 34.0 µg mL-1 for epicatechin and 6.2 µg mL-1 for caffeic acid) from samples. The results confirm that tailoring with water can successfully adjust the viscosity and extraction efficiency of DESs, for effective extraction of bioactive compounds from samples.