The authors report the autopsy case of a 73‐year‐old man with widespread, metastatic, malignant chondroid syringoma, with a long clinical history. Three years after resection of the primary tumor on the back, the tumor recurred at the same site, metastasized to the cervical lymph nodes 7 years later, and finally, after 13 years exhibited widespread metastases. Histologically, the tumor showed cords and nests of cuboidal or polygonal tumor cells with little cellular pleomorphism and few mitoses surrounded by a mucoid matrix. Histochemically, the matrix contained hyaluronic acid and sulfated acid mucopolysaccharides, such as chondroitin sulfate A and/or C. To the knowledge of the authors there have been nine reported cases of malignant chondroid syringoma in the English literature, four of which had distant metastasis. A review of the literature reveals that malignant chondroid syringoma is more common in women and occurs most often in trunk and extremities, which is in contrast to its benign counterpart, its histologic appearances vary greatly, and it may even have benign appearances.

An unprecedented photocatalytic system consisting of benzimidazolium aryloxide betaines (BI+–ArO–) and stoichiometric hydride reducing reagents was developed for carrying out desulfonylation reactions of N-sulfonyl-indoles, -amides, and -amines, and α-sulfonyl ketones. Measurements of absorption spectra and cyclic voltammograms as well as density functional theory (DFT) calculations were carried out to gain mechanistic information. In the catalytic system, visible-light-activated benzimidazoline aryloxides (BIH–ArO–), generated in situ by hydride reduction of the corresponding betaines BI+–ArO–, donate both an electron and a hydrogen atom to the substrates. A modified protocol was also developed so that a catalytic quantity of more easily prepared hydroxyaryl benzimidazolines (BIH–ArOH) is used along with a stoichiometric hydride donor to promote the photochemical desulfonylation reactions.

Benzimidazolium naphthoxide (ONap-BI) was first synthesized and utilized as an unprecedented betaine photoredox catalyst. Photoexcited state of ONap-BI generated by visible light irradiation catalyzes the reductive deiodination as well as desulfonylation reactions in which 1,3-dimethyl-2-phenylbenzimidazoline (Ph-BIH) cooperates with as an electron and hydrogen atom donor. Significant solvent effects on the reaction progress were discovered, and specific solvation toward imidazolium and naphthoxide moieties of ONap-BI was proposed.

A visible light promoted process for desulfonylation of N-sulfonylamides and -amines has been developed, in which 1,3-dimethyl-2-hydroxynaphthylbenzimidazoline (HONap-BIH) serves as a light absorbing, electron and hydrogen atom donor, and a household white light-emitting diode serves as a light source. The process transforms various N-sulfonylamide and -amine substrates to desulfonylated products in moderate to excellent yields. The observation that the fluorescence of 1-methyl-2-naphthoxy anion is efficiently quenched by the substrates suggests that the mechanism for the photoinduced desulfonylation reaction begins with photoexcitation of the naphthoxide chromophore in HONap-BIH, which generates an excited species via intramolecular proton transfer between the HONap and BIH moieties. This process triggers single electron transfer to the substrate, which promotes loss of the sulfonyl group to form the free amide or amine. The results of studies employing radical probe substrates as well as DFT calculations suggest that selective nitrogen-sulfur bond cleavage of the substrate radical anion generates either a pair of an amide or amine anion and a sulfonyl radical or that of an amidyl or aminyl radical and sulfinate anion, depending on the nature of the N-substituent on the substrate. An intermolecular version of this protocol, in which 1-methyl-2-naphthol and 1,3-dimethyl-2-phenylbenzimidazoline are used concomitantly, was also examined.

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