Synlett

The energy and stability properties of energetic materials are often contradictory to each other (e.g., high energy vs low thermal stability). There is no doubt that it is still challenging to explore the effective balance between energetic performance and molecular stability, especially for melt-castable materials. In this study, we selected the 4-methoxy-3,5-dinitropyrazole framework and a stable nitro group to design a new energetic melt-castable compound, namely 4-methoxy-3,5-dinitro-1-(nitromethyl)-1H-pyrazole (MDNNMP). Compared with the N-methylation product DMDNP and the nitrato-substituted derivative MC-7, MDNNMP exhibits a better balanced performance, including good thermal stability (Td
: 203.7 °C), detonation velocity (Dv
: 8099 m s–1) and impact sensitivity (20 J). The favorable balanced performance of MDNNMP suggests that it is a suitable candidate as a high-performance melt-castable material. Additionally, compared with the nitratomethyl group, the nitromethyl group demonstrates superior advantages in performance regulation.

The manganese(I)-catalyzed allylation of the amino acid tryptophan is realized under exceedingly mild conditions using water as a sustainable and non-hazardous reaction medium, instead of classical organic solvents, with great potential for green and sustainable chemistry. Synthetically useful α,β-unsaturated esters can be accessed by reaction with Morita–Baylis–Hillman (MBH) adducts following a fast C–H activation approach. The robustness of this procedure is reflected by kinetic analysis at different reaction temperatures and reduced catalyst loadings are employed.

Synlett 2024; 35: VII-DOI: 10.1055/s-0043-1763689Georg Thieme Verlag KG Rüdigerstraße 14, 70469 Stuttgart, GermanyArticle in Thieme eJournals:Table of contents

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.