The Balz-Schiemann synthesis of aryl fluorides via the thermal decomposition of aryl diazonium tetrafluoroborate salts represents both the earliest and the most proverbial example of the BF4 ion as a nucleophilic fluoride source. Mechanistic studies of the Balz-Schiemann reaction have accrued strong experimental support for an SN1 mechanism via the intermediacy of an aryl cation, which is quenched by fluoride transfer directly from the BF4 ion. A notable advance in this area has been the development by Ohmori and co-workers of a fluorinative variant of the Mitsunobu reaction, involving the electrooxidative generation and subsequent thermal decomposition of alkoxytriphenylphosphonium tetrafluoroborates, allowing for the conversion of alcohols to the corresponding alkyl fluorides with inversion of configuration. Although stereoselectivity during C-F bond formation for reactions proceeding via (putative) carbocation intermediates can be highly variable, the ring-opening of strained rings or ?iranium intermediates via fluoride transfer from fluoroborate ions typically proceeds with high stereoselectivity.

Beyond the Balz-Schiemann reaction: the utility of tetrafluoroborates and boron trifluoride as nucleophilic fluoride sources.

Methods for direct alkene diamination, new & old

Endothelial cells (ECs) constitute the innermost layer in all blood vessels to maintain the structural integrity and microcirculation function for coronary microvasculature. Impaired endothelial function is demonstrated in various cardiovascular diseases including myocardial infarction (MI), which is featured by reduced myocardial blood flow as a result of epicardial coronary obstruction, thrombogenesis, and inflammation. In this context, understanding the cellular and molecular mechanisms governing the function of coronary ECs is essential for the early diagnosis and optimal treatment of MI. Although ECs contain relatively fewer mitochondria compared with cardiomyocytes, they function as key sensors of environmental and cellular stress, in the regulation of EC viability, structural integrity and function. Mitochondrial quality control (MQC) machineries respond to a broad array of stress stimuli to regulate fission, fusion, mitophagy and biogenesis in mitochondria. Impaired MQC is a cardinal feature of EC injury and dysfunction. Hence, medications modulating MQC mechanisms are considered as promising novel therapeutic options in MI. Here in this review, we provide updated insights into the key role of MQC mechanisms in coronary ECs and microvascular dysfunction in MI. We also discussed the option of MQC as a novel therapeutic target to delay, reverse or repair coronary microvascular damage in MI. Contemporary available MQC-targeted therapies with potential clinical benefits to alleviate coronary microvascular injury during MI are also summarized.

Coronary microvascular injury in myocardial infarction: perception and knowledge for mitochondrial quality control.

Stereoselective reactions of nitro compounds in the synthesis of natural compound analogs and active pharmaceutical ingredients

A method for the oxidative nitration of alkenes using a combination of tert-butyl nitrite and molecular oxygen to give β-nitro alcohols and their nitrate derivatives has been developed. The present reaction provides a practical method for the synthesis of nitro compounds because of the mild reaction conditions, the use of inexpensive reagents and a simple experimental procedure.

Oxidative Nitration of Alkenes with tert-Butyl Nitrite and Oxygen

Aluminum—Isopropanol Reduction of tert-Nitronitriles: An Unusual Structure of the Reduction Products.

(2E,4E)-5-Aryl-2-(2-benzyloxyethyl)penta-2,4-dien-1-als (aryl is phenyl and 4-methox-yphenyl) were reduced with NaBH4 quantitatively and stereospecifically to the corresponding penta-2(E),4(E)-dien-1-ols. The hydroxymethyl group in the latter was transformed into a methyl one with a stereoselectivity of 92–97%. Debenzylation of the resulting (1E,3Z)-1-aryl-6-benzyloxy-4-methylhexa-1,3-dienes with AlCl3 in the presence of PhNMe2 afforded the target (3Z,5E)-6-aryl-3-methylhexa-3,5-dien-1-ols; the configuration of the C=C bonds in the conjugated aryl diene systems was retained at 95%.

Stereocontrolled Synthesis of (3Z,5E)‐6‐Aryl‐3‐methylhexa‐3,5‐dien‐1‐ols, Intermediates in the Synthesis of Strobilurin Antibiotics.

The reaction of N -(2-phenylthiopent-4-enoyl)pyrrolidine with bromine results in the stereoselective formation of 1,4-tetramethylene(5 S * -bromomethyl-3 R * -phenylthiotetrahydro-2,2-furylidene)ammonium bromide.

Stereoselective Formation of a 3,5‐trans‐Disubstituted 1,4‐Tetramethylene(tetrahydro‐2,2‐furylidene)ammonium Salt in Bromination of 2‐Phenylthiopent‐4‐enoic Acid Dialkylamide.

Reactions of alkenes with nitrogen oxides and other nitrosating and nitrating reagents are considered. The bibliography includes 134 references.

Andrei V. Stepanov

Papers

Aluminum—Isopropanol Reduction of tert-Nitronitriles: An Unusual Structure of the Reduction Products.

Stereocontrolled Synthesis of (3Z,5E)‐6‐Aryl‐3‐methylhexa‐3,5‐dien‐1‐ols, Intermediates in the Synthesis of Strobilurin Antibiotics.

Stereoselective Formation of a 3,5‐trans‐Disubstituted 1,4‐Tetramethylene(tetrahydro‐2,2‐furylidene)ammonium Salt in Bromination of 2‐Phenylthiopent‐4‐enoic Acid Dialkylamide.

Reactions of Alkenes with Nitrogen Oxides and Other Nitrosating and Nitrating Reagents

Cytochemical analysis of spatial structure of glycogen molecules in rat hepatocytes