Synthesis of 4-Oxoisoxazoline N-Oxides via Pd-Catalyzed Cyclization of Propargylic Alcohols with tert-Butyl Nitrite

Calcium sulfide-organosilicon complex for sustained release of H2S in strongly acidic wastewater: Synthesis, mechanism and efficiency

Sulfide precipitation is an efficient method to remove Cu(II) and As(III) from strongly acidic wastewater, but the instantaneous release of H₂S from traditional sulfuration reagents causes serious H₂S pollution. Moreover, the obtained precipitates are mixtures of CuS and As₂S₃, leading to difficulties in resource recovery. In this study, a calcium sulfide-organosilicon complex (CaS-OSCS), in which CaS was coated into a matrix of {[O_1.5Si(CH₂)₃NH]CS}_n (OSCS) via the coordination bonding, was developed. OSCS, as a matrix of CaS-OSCS, can ensure the sustained and stable release of H₂S under strongly acidic conditions owing to its low swelling (1.75% swelling ratio) and excellent acid resistance. The release longevity of H₂S from CaS-OSCS extended from 5 min up to 50 min compared with that from CaS because the hydrophobic OSCS prevented solution diffusing to the pores of CaS-OSCS and thus slowed down the hydrolysis of CaS in pores. 99% of Cu(II)/As(III) was precipitated without H₂S escape, and the dosage of sulfuration reagents was reduced by 30%. In addition, CaS-OSCS improved the selective separation of copper from wastewater, and a separation factor between Cu(II) and As(III) reached 2376. This study provides a potential approach for the elimination of H₂S pollution and selective recovery of copper.

Meyer-Schuster-Type Rearrangement of Propargylic Alcohols into α-Selenoenals and -enones with Diselenides

We describe a mild and broadly applicable protocol for the preparation of a diverse array of multisubstituted α-selenoenals and -enones from readily accessible propargylic alcohols and diselenides. The transformation proceeds via the Selectfluor-promoted selenirenium pathway, which enables selenenylation/rearrangement of a variety of propargylic alcohols. Gram-scale experiments showed the potential of this synergistic protocol for practical application.

Oxidative Dehydrogenation of Hydrazobenzenes toward Azo Compounds Catalyzed by tert-Butyl Nitrite in EtOH

We describe a tert-butyl nitrite-catalyzed oxidative dehydrogenation of hydrazobenzenes for producing azobenzenes. This method proceeds at ambient temperature and under an atmospheric environment by employing eco-friendly EtOH as the medium, representing a mild, general route to the synthesis of various symmetrical and nonsymmetrical azobenzenes in excellent yields with broad functional group tolerance.

Rapid construction of cyclopenta[b]naphthalene frameworks from propargylic alcohol tethered methylenecyclopropanes

We have developed a new synthetic methodology for the rapid construction of cyclopenta[b]naphthalene frameworks from the reaction of propargylic alcohol tethered methylenecyclopropanes with mesyl chloride in the presence of triethylamine through cascade cyclization. The reaction can be performed under mild conditions without the use of transition metals, affording the target products in moderate to good yields, and this cyclization reaction process can be scaled up to a gram-scale synthesis.

Generation, optimization and characterization of novel anti-prion compounds

Prions are misfolded proteins involved in neurodegenerative diseases of high interest in veterinary and public health. In this work, we report the chemical space exploration around the anti-prion compound BB 0300674 in order to gain an understanding of its Structure Activity Relationships (SARs). A series of 43 novel analogues, based on four different chemical clusters, were synthetized and tested against PrP^Sc and mutant PrP toxicity assays. From this biological screening, two compounds (59 and 65) emerged with a 10-fold improvement in anti-prion activity compared with the initial lead compound, presenting at the same time interesting cell viability.

Synthesis and application of α-carbonyl nitrile oxides

A strategy has been developed to synthesize α-carbonylfuran and isoxazole using tert-butyl nitrite (TBN) as a nitrogen source.

Lewis or Brønsted acid-catalysed reaction of propargylic alcohol-tethered alkylidenecyclopropanes with indoles and pyrroles for the preparation of polycyclic compounds tethered with indole or pyrrole motif

We developed a facile synthetic method to access the cyclopenta[b]naphthalene skeleton from Lewis or Brønsted acid-catalysed propargylic alcohol-tethered alkylidenecyclopropanes with indole and pyrrole derivatives.

Synthesis of Isoxazolines and Oxazines by Electrochemical Intermolecular [2 + 1 + n] Annulation: Diazo Compounds Act as Radical Acceptors

Reported herein is an unprecedented synthesis of isoxazolines and oxazines through electrochemical intermolecular annulation of alkenes with tert-butyl nitrite, in which diazo compounds serve as radical acceptors. Notably, [2 + 1 + 2] and [2 + 1 + 3] annulations occur when styrenes and allylbenzenes are used as substrates, respectively. The latter reaction undergoes group migration to form more stable radical, manifesting radical route instead of conventional 1,3-dipolar cycloaddition occurs. Moreover, scale-up experiments suggest the potential application value of these transformations in industry.

Design of a simple and efficient synthesis for bioactive novel pyrazolyl–isoxazoline hybrids

A simple and new methodology has been developed for the synthesis of novel bioactive pyrazolyl–isoxazoline hybrids using pyrazoline-substituted oxime. Among the hybrid materials, 6m and 6p were found to show the best anti-bacterial and anti-fungal activities.