Aldehydes as Alkylating Agents for Ketones

Direct synthesis of ethers from alcohols & aldehydes enabled by an oxocarbenium ion interception strategy

A new method has been established for formation of ethers from aldehydes and alcohols - a net reductive etherification. Reactions of these entities with phosphines in the presence of acid enable formation of α-(alkoxyalkyl)phosphonium salts, which, upon hydrolysis, result in formation of ether products in isolated yields of 63-92%. Formation and hydrolysis of the α-(alkoxyalkyl)phosphonium salts were done in an efficient telescoped two-step, one-pot process that does not require inert atmosphere conditions. Formation of the key phosphonium salt intermediates was found to occur in preference to acetal formation and is proposed based on both experimental and computational evidence to involve interception of oxocarbenium ions formed by reaction of the aldehyde, alcohol and acid by phosphine. This method represents the first instance in which net reductive etherifications have been achieved without the requirement for use of hydrides or hydrogen as reductants, and exhibits excellent functional group tolerance, thus enabling facile hydride-free synthesis of ethers. These are amongst the most important functional groups in organic synthesis. The new etherification method also enables deuteride-free synthesis of deuterated ethers.

Antioxidant Capacity, Phytochemicals, Minerals, and Chemical Pollutants in Worker Honey Bee (Apis mellifera L.) Broods from Northern Thailand: A Safe and Sustainable Food Source

Honey bee brood (HBB) (Apis mellifera L.), a traditional protein source, has been studied for its nutritional value, but bio-functional properties and safety concerns have not been verified. This study examined the Antioxidant capacity, phytochemicals, minerals, and chemical pollutants in worker broods from several apiaries in Northern Thailand. HBB samples were lyophilized to evaluate antioxidant capacity using ABTS, DPPH, and FRAP assays, tests with water, and 70% ethanol extracts. Phytochemicals were identified using LC-QTOF-MS; pollutants were analyzed chromatographically, and minerals were determined using ICP-OES. The results showed that the evaluated antioxidant capacity of the ethanol extracts included DPPH 2.04-3.37 mg/mL, ABTS 21.22-33.91 mg/mL, and FRAP 50.07-104.15 mg AAE/100 g dry weight. Water extracts had outstanding antioxidant activities except for ABTS, with DPPH 10.67-84.97 mg/mL, ABTS 9.25-13.54 mg/mL, and FRAP 57.66-177.32 mgAAE/100 g dry weight. Total phenolics and flavonoids in ethanol extracts ranged from 488.95-508.87 GAE/100 g to 4.7-12.98 mg QE/g dry weight, respectively. Thirteen phytochemicals were detected and contained adequate mineral contents in the HBBs from different locations found, which were K, Ca, Mg, and Na, and no heavy metals or pollutants exceeded safe levels. These results imply that HBB from different apiaries in Northern Thailand is a nutritious food source with considerable antioxidants and a safe and sustainable food source.

Reductive Aldol-type Reactions in the Synthesis of Pharmaceuticals

The efficient chemo-, regio- and stereoselective formation of saturated carbon-carbon fragment is the critical challenge of organic synthesis; therefore, developing new methods for formation of these bonds is paramount. The rising interest for reductive aldol-type reactions is conditioned by its versatile applications, allowing the efficient formation of carbon-carbon bonds. The review aims to highlight the advantages and disadvantage of reductive aldol-type reactions to total synthesis of pharmaceutical substances in order to summarize knowledge and encourage further investigation of the field.

Carbon monoxide-driven osmium catalyzed reductive amination harvesting WGSR power

First osmium-catalyzed reductive amination under the water gas–shift reaction conditions was developed. Proposed catalytic system demonstrates high performance even at the catalyst loading as low as 0.0625 mol%.