Phenyl substitution at position 5 on the hydantoin ring of a series of N-halamine derivatives, including an antimicrobial siloxane used for coating surfaces, has been employed to better understand the biocidal activities and stabilities of these compounds in the presence of water and exposure to ultraviolet irradiation. This phenyl derivatization of the hydantoin ring at its 5 position does, in fact, affect the antimicrobial efficacy of the siloxane against Staphylococcus aureus and Escherichia coli O157:H7, and its stability toward hydrolyses and ultraviolet light exposure. The phenyl substitution caused weakening of the N-Cl bond at the 1 position on the hydantoin ring, leading to an increase in biocidal activity but a decrease in stability. Model compounds were studied experimentally and theoretically at the (U)B3LYP/6-311++G(2d,p) level of theory in order to better explain the observations. It was found that the phenyl moiety at position 5 on the hydantoin ring can interact with the oxidative chlorine atom bonded to the amide nitrogen atom at position 1 which then results in a less stable N-Cl bond.

The Co(III)-catalyzed redox-neutral annulation of benzamides and acrylamides with vinylene carbonate for the synthesis of isoquinolinones and pyridinones has been developed. This protocol employing inexpensive Co(III) as the catalyst tolerated diverse functional groups and substitution patterns, affording the target products with good to excellent yields. The synthetic utility of this transformation was demonstrated by a three-step synthesis of gusanlung D, 8-oxopseudopalmatine, and oxopalmatine.Letter pubs.acs.org/OrgLett

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The use of imines as a H acceptor for Rh(iii)-catalyzed spirocyclization of 3-arylquinoxalinones and alkynes via a C–H functionalization/[3 + 2] annulation sequence has been achieved.

A Rh(III)-catalyzed synthesis of isoquinolinones and pyridinones bearing a methylene motif is presented. This protocol using easily accessible 1-cyclopropyl-1-nitrosourea as the precursor of propadiene features simple and practical manipulation and tolerates a broad spectrum of functional groups, including strong coordinating N-containing heterocyclic substituents. Late stage diversification and the rich reactivity of methylene for further derivations demonstrate the value of this work.