Synlett

Upon treatment of chiral β-trifluoromethyl-α,β-unsaturated N-acylated oxazolidin-2-ones with a range of alcohols using phosphazene base as a catalyst, the unexpected cascade esterification/stereoselective aza-Michael addition was observed. The reactions proceeded with high diastereoselectivities (up to >99:1) to give a series of enantioenriched aza-Michael addition products in good to high yields. The structure and stereochemistry of the representative aza-Michael adduct were confirmed by X-ray crystal structure analysis. The plausible mechanism was proposed on the basis of the experimental results.The synthetic transformations of chiral aza-Michael addition products were also demonstrated highlighting the synthetic application of the present work.

Synlett 2024; 35: V-DOI: 10.1055/s-0043-1774981Georg Thieme Verlag KG Rüdigerstraße 14, 70469 Stuttgart, GermanyArticle in Thieme eJournals:Table of contents

Synlett 2024; 35: A118-A133DOI: 10.1055/s-0043-1763991Georg Thieme Verlag KG Rüdigerstraße 14, 70469 Stuttgart, GermanyArticle in Thieme eJournals:Table of contents

Twenty novel 4-bromocoumarin derivatives bearing a sulfonamide moiety were designed and synthesized. Their antiviral and antibacterial activities were systematically evaluated. The test results show that all the target compounds possess moderate to excellent antiviral and antibacterial activities. Among all target compounds, one compound exhibited good antiviral activity against TMV, CMV, and PVY, which is superior to ribavirin. Moreover, two target compounds exhibited good in vitro antibacterial activity against Psa, with an EC50 value of 44.9 mg/L and 49.3 mg/L, respectively, which were better than thiodiazole copper and zinc thiazole, with an EC50 value of 56.3 mg/L and 50.2 mg/L, respectively. The results provide insights for the development of multifunctional pesticides.

C-Aryl glycosides have attracted considerable interest as biologically active natural products and as O-aryl glycoside mimetics in drug discovery. Here, we describe a straightforward synthesis of C-aryl glycosides by photoredox/Ni dual-catalyzed reductive cross-coupling between glycosyl bromides and aryl bromides. This methodology enables a highly α-stereoselective synthesis of C-aryl glucosides, galactosides, and mannosides.

A convergent strategy for the stereoselective synthesis of polyketide segments of hybrid natural products nemamide A and euglenatides D–E has been developed for the first time. The salient features of this gram-scale synthesis include Trost–Rychnovsky alkyne rearrangement, HWE olefination, regioselective epoxide ring opening, Prins–Ritter cyclization, and subsequent reductive cleavage of the substituted THP ring. The optimized route is modular and could be tunable to access the other polyketide counterparts of these families of metabolites.

Natural products containing highly oxygenated furanofuranone fragments are known for their potent biological activity, but also for their challenging total synthesis. In this study, the synthesis of five novel dephenylated (–)-goniofufurone analogues was completed and their cytotoxic activity against eight malignant and one normal human cell line was evaluated. Compared with previous syntheses of similar analogues, the synthesis was carried out starting from l-xylose, resulting in improved yields and a reduced number of synthetic steps for three divergent intermediates.

A triazine-based reagent, 2-hydroperoxy-4,6-dimorpholino-1,3,5-triazine (Triazox-II), was developed for alkene epoxidation. This reagent can be prepared from inexpensive starting materials (cyanuric chloride and morpholine) on a 15 mmol scale in two steps with 54% overall yield and isolated as a pure, bench-stable solid with low sensitivity to impact and friction. Triazox-II exhibited higher solubility in chlorinated solvents than the previously reported reagent Triazox. Epoxidation using Triazox-II was conducted in various solvents, with a preference for CH2Cl2 at 0.5 M concentration, resulting in epoxides in 83–94% yield. The reaction was conducted under mild conditions owing to the low acidity of the reaction coproduct.

The fusion of transition-metal catalysis with radical chemistry provides a versatile platform for the asymmetric radical carboazidation of alkenes to enable the rapid assembly of highly functionalized chiral azide compounds. Here, we present an iron-catalyzed asymmetric three-component radical carboazidation that processes electron-deficient alkenes by direct activation of aliphatic C–H bonds. This strategy provides access to a range of valuable chiral azides from readily available chemical feedstocks bearing a tetrasubstituted carbon stereocenter, and their synthetic potential is further showcased through straightforward transformations to provide other valuable enantioenriched building blocks.

Chemical synthesis of octasaccharide motif from cranberry arabinoxyloglucan oligosaccharides with antiadhesion activities has been achieved for the first time. Synthetic approach highlights the following features: 1) stereoselective constructions of 1,2-cis-Xyl bonds via the combination of reagent modulation and remote participation; 2) modular [1+3+1+3] orthogonal one-pot assembly of the target octasaccharide on the basis of glycosyl ortho-(1-phenylvinyl)benzoate, which avoids the issues such as aglycone transfer associated with one-pot glycosylation based on thioglycosides.