Sulfonyl hydrazides are widely used as organic reagents. Advances in the past decade are summarized in the following categories by key intermediates: (1) [RO2S.]; (2) RO2SSR; (3) [ArS.]; (4) [RO2S−]; (5) RSO2‐[Metal] species; (6) Ar‐[Metal] species; (7) RSX; (8) RS‐DBU; (9) nucleophilic amino group; (10) sulfonyl hydrazides as diazene or sulfinic acid surrogate. Reactions with alkenes, alkynes, aldehydes, alcohols, thiophenol, Grignard reagents, among others, are discussed. We hope this review will promote future research in this area.

The accumulation of nonbiodegradable petrochemical-based polymers in the environment motivates the development and use of low-cost, eco-friendly, and biodegradable polymers. A series of biodegradable poly(butylene adipate-co-terephthalate) composites reinforced by sustainably sourced nanochitin were successfully prepared using melt blending and compression molding methods. Structural, thermal, and mechanical characterizations of poly(butylene adipate-co-terephthalate) (PBAT)/nanochitin composites were performed. SEM revealed that the nanochitin was uniformly dispersed throughout the PBAT matrix at low contents (<2 wt %), while DSC analyses revealed a corresponding increase in the crystallinity (32.6% enhancement) of the PBAT matrix. The tensile strength and elongation at break of the PBAT/nanochitin composite containing 0.5 wt % nanochitin were higher by 82.5 and 64.2%, respectively, compared with pristine PBAT. The Chitin-0.5 composite also showed improved thermal stability compared with PBAT (the char yield improved by 8%) due to the uniform dispersion of nanochitin in the PBAT matrix. The enhanced performance of the PBAT/nanochitin composites, prepared without an added compatibilizer, informs the development of improved biodegradable PBATbased polymers.

It is a trend to construct multicomponent room temperature phosphorescence/RTP doped materials in the future to improve phosphorescence performance by using the advantage that the host in the doped system can be used as a container containing other components. Herein, the multicomponent doped systems are constructed with two isoquinoline derivatives (OxISQ and PrISQ) as the guests, diphenyl sulfoxide/SDB as the host, and alkali (KOH) as the fourth component. Bicomponent doped material OxISQ/SDB has strong cyan RTP, whereas PrISQ/SDB has almost no RTP activity. The effect of KOH on the phosphorescence intensity of OxISQ/SDB is excitation-dependent. When λex = 365 nm, KOH turns off the phosphorescence emission, revealing the intensity of KOH-added three-component doped material OxISQ/SDB/KOH is significantly weaker than that of OxISQ/SDB, whereas KOH exhibits the turn-on property for OxISQ/SDB at λex = 385 nm. For PrISQ/SDB, KOH displays permanent turn-on ability, and PrISQ/SDB/KOH has strong yellow-orange RTP. More deeply, a two-guest four-component doped system OxISQ/PrISQ/SDB/KOH is constructed, and from OxISQ/PrISQ/SDB to OxISQ/PrISQ/SDB/KOH, with the increase of KOH, the phosphorescence colors gradually change from cyan to green to yellow to orange at λex = 365 nm, but the color only can change directly from cyan to yellow-orange at λex = 385 nm. In addition, OxISQ/PrISQ/SDB/KOH exhibited a time-dependent afterglow color from orange-yellow to cyan over 2 s due to the different phosphorescence lifetime, intensity, and wavelength of each component. The experimental results confirmed that phenylhydroxyl-containing guests react with KOH to form organic salts, thereby inducing new excitation and emission wavelengths in the doped materials. This work is the first to construct a four-component doped system with dual guests that can undergo chemical reactions. Moreover, taking advantage of the water solubility of KOH, the doped materials have achieved advanced anticounterfeiting writing and printing in the aqueous phase.

The doped materials have almost only RTP and TADF emissions, the hosts can tune the proportion of excitons in TADF and RTP, resulting in the afterglow colors gradually redshift from cyan to yellow-orange.

Recent advances of -keto acids were summarized as five categories according to their triggered mechanisms:(1) decarboxylative enolate nucleophiles;(2) addition without [a] 526 Scheme 3. Reactions with in situ generated isatylidenemalononitriles.Scheme 4. 1,3-Acetonedicarboxylic acid as 1,3-bis-pro-nucleophile. could promote decarboxylative Michael reactions of unreactive substrates. Besides, an asymmetric chiral bis(oxazoline) copper(II)-catalyst 5.5 would achieve the single-pot procedure to prepare 5.4 (Scheme 5).Scheme 5. Michael/aldol reaction. The Chiba group [3i] presented a manganese(III)-catalyzed preparation of pyrroles 6.2 from reactions of vinyl azides 6.1 with -keto acids (Equation 6-1). It might be initiated by a radical pathway, giving iminyl radical 6.3 by releasing of N 2 , and CO 2 . Then, 6.3 underwent intramolecular addition to give inter-Eur. J. Org. Chem. 2020, 525-538 www.eurjoc.org 528 Scheme 10. Addition to allenes.Scheme 11. Coupling with alkenes.Scheme 12. Aldol reactions from α,α-difluoro--keto acid derivatives.