Synlett 2024; 35: e2-e2DOI: 10.1055/s-0043-1763686Georg Thieme Verlag KG Rüdigerstraße 14, 70469 Stuttgart, GermanyArticle in Thieme eJournals:Table of contents | Full text
Jun Deng (left) received his B.Sc. from Lanzhou University and his Ph.D. from the Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences (2014) with Professor Ang Li. After a short period of postdoctoral research in the lab of Professor Andrew Myers at Harvard University (2014–2016), he was appointed a Pioneer ‘Hundred Talents Program’ Researcher at Kunming Institute of Botany, Chinese Academy of Sciences in 2017. In December 2020, he moved to Nankai University where he is a professor at the College of Chemistry. He received the Thieme Journals Award (2020). His research focuses on natural product total synthesis and medicinal chemistry.
Yefeng Tang (right) earned his B.S. from Lanzhou University (1995–1999) and his M.S. from the Institute of Materia Medica, Chinese Academy of Medical Science (1999–2002). From 2003 to 2006, he pursued his Ph.D. under the guidance of Professor Zhen Yang and Professor Jiahua Chen at Peking University. Subsequently, he conducted postdoctoral research with Prof. K. C. Nicolaou at The Scripps Research Institute between 2006 and 2009. In 2010, he commenced his independent career at the School of Pharmaceutical Sciences, Tsinghua University, where he is now a tenured professor. His primary research interests encompass the total synthesis of natural products, the development of synthetic methodologies, and the discovery of antiviral and anti-aging drugs.
Herein, we report an efficient method to access difluoromethyl ethers of thiols and phenols using ethyl bromodifluoroacetate and K2CO3. This method demonstrates chemoselective difluoromethylation of thiols and phenols in the presence of amines. The current method also discloses the synthesis of bis(aryloxy)fluoromethane compounds which are least reported in the literature. Mechanistic investigations revealed that the reaction proceeds through a nucleophilic substitution pathway. We strongly believe this protocol would offer an efficient alternative to earlier photocatalyzed or radical-mediated difluoromethylation methods and it has a great potential in the scale-up of pharmaceutical and agrochemical intermediates that possess difluoromethyl group.
An ultrasound-assisted expedient protocol has been developed for the synthesis of imidazo[1,2-a]pyridines and imidazo[2,1-b]thiazoles by the C–H functionalization of ketones using a KI/tert-butyl hydroperoxide catalytic system. The reaction takes place in water, a green solvent, and does not require a metal catalyst; it also gives good yields of the products. The method offers numerous noteworthy characteristics, including mild reaction conditions, the absence of a base, broad functional-group compatibility, and excellent reaction yields. Moreover, it avoids the use of costly and air-sensitive chemicals, and can be conducted under ambient reaction conditions.
3-Substituted benzothiophenyl analogues of tertiary cis-β-benzylstyrenes undergo triflic acid catalyzed dearomative spirocyclization at room temperature to afford compounds containing vicinal quaternary centers. Hydroarylation of the styrene is a competing process that occurs preferentially within substrates possessing electron-rich styrenyl alkenes, or an indole in place of the benzothiophene.
The first total synthesis of phenethylamine alkaloid based natural products discolin A, B, E and bacillimidazole B is reported, which were isolated from marine sea bacteria Tenacibaculum discolor sv11 and marine sponge. Total syntheses of discolin A, B, E and bacillimidazole B are achieved in two linear steps including condensation reaction and N-alkylation reaction with an overall yield of 68%, 35%, 65%, and 32%, respectively. A total of 24 analogues are prepared with moderate to excellent yield. All the natural products and their analogues were screened for antibacterial activity. The most active compound showed an IC50 of 122.1 nM against P. aeruginosa.
The mechanistic details of a reported allylation reaction are investigated by means of Stern–Volmer experiments and nanosecond transient absorption spectroscopy. Both reference substrates, i.e., an allylic chloride and a trifluoroacetamide, are inefficient quenchers but large quenching rate constants are observed upon the addition of Ni(COD)2 and a bisoxazoline ligand. The large quenching rate constants and absence of observable photoproducts are consistent with a mechanism that operates by energy transfer between the excited-state iridium photosensitizer and the nickel complex.
We report a convergent synthesis of heteroaryl/aryl-annulated pyridine and quinoline derivatives by a metal-free Povarov reaction. para-Toluene sulfonic acid was used as the catalyst in this reaction, which produced the products in good yields from the corresponding aromatic amines and ethyl vinyl ether. A pyridocoumarin and a pyridopyrimidine product were evaluated for their mosquito larvicidal activity against the third instar larvae of the dengue vector mosquito Aedes aegypti. Examination of morphological changes in the larvae showed damage to the target body part after treatment with both the pyridocoumarin and pyridopyrimidine products at the LC50 concentrations.
Multiply substituted pyrroles are found in medicines, natural products, and functional materials. A general method for introducing functionality on the pyrrole ring is thus required. Herein, a regiocontrolled halogen dance reaction and an in situ transmetalation of α-functionalized bromopyrroles are reported. Selective generation of the isomeric pyrrolylmetal species was achieved by using an ethyl ester or a phenyl group at the α-position of the pyrrole and by switching between the halogen dance reaction and in situ transmetalation. These reactions proceeded smoothly when an N,N-dimethylsulfamoyl group was attached to the pyrrole nitrogen atom, providing the corresponding products in 68% to quantitative yields on 1-mmol scale. This method was applicable to the formal synthesis of Kendine 91.
A methodology to access reactive hydride moieties is highly desirable, yet limited. Multimetallic hydride fragments are notable for their heightened reactivity and catalysis, but deliberate access to these species is lacking. In this highlight, we discuss recent developments by our group in the design of a new heterometallic complex that invokes an architecture designed to provide modular access to reactive hydride moieties by leveraging metal hydrides in combination with pendent donors to a model heterotrimetallic Ni–(Al–H)2 complex. An amplification of insertion-based reactivity has been examined in the hydrofunctionalization of quinolines, and our complex substantially outperformed the parent aluminum hydride LAlH (L = ligand). A potential rationale for the dramatically increased reactivity, and a further examination of these motifs and methodology in catalysis are also discussed.1. Introduction2. Heterometallic Hydride Design and Characterization3. Amplification in Catalysis4. Summary and Outlook