New phenol and chromone derivatives from the endolichenic fungus Daldinia species and their antiviral activities

Three new phenolic metabolites, daldispols A–C (1–3), two new chromone derivatives, (5R,7R)-5,7-dihydroxy-2-methyl-5,6,7,8-tetrahydro-4H-chromen-4-one (9) and (5R,7R)-5,7-dihydroxy-2-propyl-5,6,7,8-tetrahydro-4H-chromen-4-one (10), together with five known phenolic compounds (4–8) and two known chromone compounds (11 and 12) were isolated from the endolichenic fungus Daldinia sp. CPCC 400770. Their structures were elucidated on the basis of spectroscopic methods, electronic circular dichroism (ECD), and comparison with reported data. Compounds 1, 3, 4, 9, and 11 exhibited significant anti-influenza A virus (IAV) activities with IC₅₀ values of 12.7, 6.4, 12.5, 16.1, and 9.0 μM, respectively, and compound 8 displayed significant anti-ZIKV activity with inhibitory ratio of 42.7% at 10 μM. The results demonstrated that the fungus Daldinia sp. CPCC 400770 might be a rich source for discovering anti-IAV secondary metabolites as potential novel leading compounds.

Eight phenols including three new ones (1–3) and four chromones including two new ones (9 and 10) were isolated from endolichenic fungus Daldinia sp. CPCC 400770, and some of them showed significant antiviral activities.

Homo-Roche ester derivatives by asymmetric hydrogenation and organocatalysis

Asymmetric hydrogenation routes to homologues of The Roche ester tend to be restricted to hydrogenations of itaconic acid derivatives, that is, substrates that contain a relatively unhindered, 1,1-disubstituted alkene. This is because in hydrogenations mediated by RhP2 complexes, the typical catalysts, it is difficult to obtain high conversions using the alternative substrate for the same product, the isomeric trisubstituted alkenes (D in the text). However, chemoselective modification of the identical functional groups in itaconic acid derivatives are difficult; hence, it would be favorable to use the trisubstituted alkene. Trisubstituted alkene substrates can be hydrogenated with high conversions using chiral analogs of Crabtree's catalyst of the type IrN(carbene). This paper demonstrates that such reactions are scalable (tens of grams) and can be manipulated to give optically pure homo-Roche ester chirons. Organocatalytic fluorination, chlorination, and amination of the homo-Roche building blocks was performed to demonstrate that they could easily be transformed into functionalized materials with two chiral centers and α,ω-groups that provide extensive scope for modifications. A synthesis of (S,S)- and (R,S)-γ-hydroxyvaline was performed to illustrate one application of the amination product.

Synphos modified Pt nanoclusters, their heterogenization by silica sol-gel entrapment, and catalytic activity in hydrogenolysis of bicyclo[2.2.2]oct-7-enes and hydrogenation of ethyl pyruvate

Platinum (Pt) colloids modified by the chiral ligand synphos were prepared with the goal of obtaining a catalytic nanomaterial and were subsequently embedded in silica to form a heterogeneous catalyst. The systems were characterized by (31)P-NMR, x-ray diffraction, molecular modeling and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTs) measurements. These colloids, both as 'quasi-homogeneous catalysts' (or soluble heterogeneous catalysts) and embedded in silica (heterogeneous catalysts) were employed in the selective hydrogenolysis of highly sterically constrained bicyclo[2.2.2]oct-7-enes and hydrogenation of ethyl pyruvate.