1121-55-7Relevant articles and documents
Copper-Catalyzed Asymmetric Radical 1,2-Carboalkynylation of Alkenes with Alkyl Halides and Terminal Alkynes
Dong, Xiao-Yang,Cheng, Jiang-Tao,Zhang, Yu-Feng,Li, Zhong-Liang,Zhan, Tian-Ya,Chen, Ji-Jun,Wang, Fu-Li,Yang, Ning-Yuan,Ye, Liu,Gu, Qiang-Shuai,Liu, Xin-Yuan
, p. 9501 - 9509 (2020)
A copper-catalyzed intermolecular three-component asymmetric radical 1,2-carboalkynylation of alkenes has been developed, providing straightforward access to diverse chiral alkynes from readily available alkyl halides and terminal alkynes. The utilization of a cinchona alkaloid-derived multidentate N,N,P-ligand is crucial for the efficient radical generation from mildly oxidative precursors by copper and the effective inhibition of the undesired Glaser coupling side reaction. The substrate scope is broad, covering (hetero)aryl-, alkynyl-, and aminocarbonyl-substituted alkenes, (hetero)aryl and alkyl as well as silyl alkynes, and tertiary to primary alkyl radical precursors with excellent functional group compatibility. Facile transformations of the obtained chiral alkynes have also been demonstrated, highlighting the excellent complementarity of this protocol to direct 1,2-dicarbofunctionalization reactions with C(sp2/sp3)-based reagents.
First Total Synthesis of Niphatesines A-D and Assignment of Absolute Configuration
Rao, A. V. Rama,Reddy, Gongiti Ravindra
, p. 8329 - 8332 (1993)
Regio/Enantioselective synthesis of niphatesines A-D is achieved making use of Pd(0) assisted 3-alkylation of pyridine as the key step.Absolute configuration of niphatesines C and D is established.
Interconversion of nicotine enantiomers during heating and implications for smoke from combustible cigarettes, heated tobacco products, and electronic cigarettes
Moldoveanu, Serban C.
, p. 667 - 677 (2022/02/02)
Physiological properties of (R)-nicotine have differences compared with (S)-nicotine, and the subject of (S)- and (R)-nicotine ratio in smoking or vaping related items is of considerable interest. A Liquid Chromatography-Mass Spectrometry/Mass Spectrometry (LC-MS/MS) method for the analysis of (S)- and (R)-nicotine has been developed and applied to samples of nicotine from different sources, nicotine pyrolyzates, several types of tobacco, smoke from combustible cigarettes, smoke from heated tobacco products, e-liquids, and particulate matter obtained from e-cigarettes aerosol. The separation was achieved on a Chiracel OJ-3 column, 250 × 4.6 mm with 3-μm particles using a nonaqueous mobile phase. The detection was performed using atmospheric pressure chemical ionization (APCI) in positive mode. The only transition measured for the analysis of nicotine was 163.1 → 84.0. The method has been summarily validated. For the analysis, the samples of tobacco and smoke from combustible cigarettes were subject to a cleanup procedure using solid phase extraction (SPE). It was demonstrated that nicotine upon heating above 450°C for several minutes starts decomposing, and some formation of (R)-enantiomer from a sample of 99% (S)-nicotine is observed. An analogous process takes place when a 99% (R)-nicotine is heated and forms low levels of (S)-nicotine. This interconversion has the effect of slightly increasing the content of (R)-nicotine in smoke compared with the level in tobacco for combustible cigarettes and for heated tobacco products. The (S)/(R) ratio of nicotine enantiomers in e-liquids was identical with the ratio for the particulate phase of aerosols generated by e-cigarette vaping.
Creation of Redox-Active PdSx Nanoparticles Inside the Defect Pores of MOF UiO-66 with Unique Semihydrogenation Catalytic Properties
Dong, Ming-Jie,Wang, Xuan,Wu, Chuan-De
, (2019/12/27)
Semihydrogenation of alkynes to produce alkenes is very important in the industry; however, over-hydrogenation heavily complicates the postprocesses, which are highly energy consuming and not environmentally friendly. One of the most efficient pathways to solve this challenging issue is to develop highly selective catalysts that could only hydrogenate alkynes and are inactive in hydrogenation of alkenes. This work presents herein an efficient catalyst, consisting of in situ created PdS0.53 nanoparticles as the redox-active sites inside the defect pores of metal–organic framework UiO-66, which demonstrates very high alkene selectivity (up to 99.5%) in semihydrogenation of easily over-hydrogenated terminal alkynes. In contrast to the traditional catalysts, strict control over the reaction time becomes the nonessential condition because the catalyst system is almost inactive in hydrogenation of alkenes. Therefore, this paradigm work provides a practically applicable pathway for the development of efficient catalysts with unique catalytic properties for selective semihydrogenation reactions.
