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Recent progress on catalytic nitrene transfer reactions with hydroxylamine derivatives as prevalent precursors is summarized in this highlight. The salient features of these N–O derived nitrene transfer reagents are that they are readily available, bench-stable, and can be facilely activated by a range of transition metal-catalysts under mild conditions. The application of these reagents in transition metal-catalysis has led to many new amidation or amination reactions, such as C–H insertions and aziridination of olefins. These reagents have also been applied in difunctionalisation of unsaturated bonds, dearomative amination of indoles, and formation of N–X bonds. Moreover, the recent achievements in photocatalysis and enzyme catalysis further emphasize the importance of these appealing reagents. This highlight provides an overview of these reactions reported in recent years. Challenges and potential opportunities for future developments are also discussed. [ABSTRACT FROM AUTHOR]

A convenient Y(OTf)3-catalyzed cascade formal [4 + 2] cyclization approach for the formation of 1,4-benzoxazine scaffolds from benzoxazoles and propargyl alcohols through a ring-opening and regioselective ring-closure process has been developed. By using this mild and practical protocol, a broad range of aldehyde-containing 1,4-benzoxazine compounds were prepared in moderate to excellent yields with good functional group tolerance. Mechanistic studies indicated that an SN1 nucleophilic substitution of benzoxazole with a propargyl cation was involved in this transformation. [ABSTRACT FROM AUTHOR]

Retraction of 'Non-matrix matched calibration of element contents in stainless steel by using nanosecond and femtosecond laser ablation inductively coupled plasma mass spectrometry' by Jiuling Meng et al., J. Anal. At. Spectrom., 2019, DOI: 10.1039/c8ja00443a. [ABSTRACT FROM AUTHOR]