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The photochemical reactivity of 1-bromo-2-oxo-1,2-dihydronaphthalene-1-carboxylates (BODNs) was demonstrated. They are inert in the dark under physiological conditions but become active as brominating reagents for tyrosine modification under visible light irradiation in the presence of a photocatalyst. The BODNs can be applied to protein labeling with bromo groups as sensitive mass tags. [ABSTRACT FROM AUTHOR]

Scavengers that capture reactive chemical substances are used to prevent the decomposition of materials. However, in the field of catalysis, the development of scavengers that inhibit background pathways has attracted little attention, although the concept will open up an otherwise inaccessible reaction space. In catalytic bromination, fast non‐catalyzed background reactions disturb the catalytic control of the selectivity, even when using N‐bromoamide reagents, which have a milder reactivity than bromine (Br2). Here, we developed a trans‐cyclooctene (TCO) bearing a 2‐pyridylethyl group to efficiently retard background reactions by capturing Br2 in bromocyclization using N‐bromosuccinimide. The use of less than a stoichiometric amount of the TCO was sufficient to inhibit non‐catalyzed reactions, and mechanistic studies using the TCO revealed that in situ‐generated Br2 provides non‐catalyzed reaction pathways based on a chain mechanism. The TCO is useful as an additive for improving enantioselectivity and regioselectivity in catalytic reactions. Cooperative systems using the TCO with selective catalysts offer an alternative strategy for optimizing catalyst‐controlled selectivity during bromination. Moreover, it also served as an indicator of Br2 involved in catalytic reaction pathways; thus, the TCO was useful as a probe for mechanistic investigations into the involvement of Br2 in bromination reactions of interest. [ABSTRACT FROM AUTHOR]

Snythesis and properties of chiral diaminodioxaphosphonium salts are discussed. A highly enantioselective protonation of [alpha]-amino acid-derived ketene disilyl acetals is reported.

Heterochiral [7,7]-spirocyclic arylaminophosphonium barfates are designed as a novel charged, cationic Bronsted acid catalyst, and their catalytic and stereocontrolling abilities are shown in the development of the highly enatioselective conjugate addition of arylamines to nitroolefins. The analysis has disclosed a new function of chiral tetraaminophosphonium cations and its potential synthetic utility, thus helping in the molecular design of chiral charged Bronsted acid catalysts.

The generation of chiral tetraaminophosphonium dialkyl phosphite is detected by low-temperature NMR analysis and its synthetic potential as a reactive P-nucleophile is shown by its application to the establishment of highly efficient and enantioselective hydrophosphonylation of various aldehydes. The analysis of the organic-base-dependent generation of the ion pair and its reactivity and selectivity as a P-nucleophile has shown that the structure of the cationic conjugate acid of the base is a major factor for generation of phosphite anions with nucleophilicity and rigorous stereocontrol.

The application of the asymmetric catalysis of chiral tetraaminophosphonium carboxylate in the highly enantioselective direct Mannich-type reaction of azlacetones is demonstrated. The structural manipulation of the cation, as well as the anion is shown to highly control the functions of the salt.

The design and the properties of chiral tetraaminophosphonium salts with four primary amino groups are discussed. The analysis shows that these salts can be easily used as the catalysts in the asymmetric direct Henry reaction.

A new variant of phosphoric acid-catalyzed C-C bond forming reaction, direct alkylation of alpha-diazoester, via C-H bond cleavage is presented. The resulting products, beta-amino-alpha-diazoesters, are highly functionalized and useful synthetic precursors for various types of beta-amino acids.