Phylogenetic Analyses and Morphological Studies Reveal Four New Species of Phellodon (Bankeraceae, Thelephorales) from China

Phellodon is a genus of ectomycorrhizal fungi with important ecological roles and exploitable biological activities. In this study, four new species of Phellodon, P. caesius, P. henanensis, P. concentricus and P. subgriseofuscus, are described from China based on morphological characters and molecular evidence. The phylogenetic analyses of Phellodon were carried out based on the ITS + nLSU gene regions and the combined sequence dataset of ITS + nLSU + nSSU + RPB1 + RPB2 gene regions. Phellodon caesius is characterized by its dark bluish-grey, dark grey to black grey pileus, ash grey to dark bluish-grey spines, and the presence of both simple septa and clamp connections on generative hyphae of stipe. Phellodon concentricus is characterized by its zonate pileal surface, dark grey context in pileus, and spongy basidiomata. Phellodon henanensis is characterized by its ash grey, light vinaceous grey to light brown pileal surface, thin context in pileus, and the presence of both simple septa and clamp connections on generative hyphae of spines. Phellodon subgriseofuscus is characterized by its fuscous to black pileal surface, white to light brown spines, and vinaceous grey context. Illustrated descriptions and the ecological habits of the novel species are provided.

The Synthesis, Structural Characterisation, and Chemoselective Manipulation of Certain Functionalised Cyclic Sulfates Derived from Chiral, Non-Racemic, and Polysubstituted Bicyclo[2.2.2]octane-2,3-diols

Certain cyclic sulfates (e.g. 23) together with various of their precursor sulfites (e.g. 21 and 22) have been prepared from the corresponding chiral, non-racemic bicyclo[2.2.2]octane-2,3-diols (e.g. 20). Such diols are obtained by engaging the corresponding enzymatically derived and enantiomerically enriched or homochiral cis-1,2-dihydrocatechol (e.g. 10) or certain derivatives in either inter- or intra-molecular Diels–Alder cycloaddition reactions. Other functionalities present within the title compounds can be chemoselectively manipulated without adversely affecting the associated sulfate residues.

The Application of Dioxygenase-Based Chemoenzymatic Processes to the Total Synthesis of Natural Products

This Minireview describes the exploitation of certain enzymatically derived, readily accessible, and enantiomerically pure cis-1,2-dihydrocatechols as starting materials in the chemical synthesis of a range of biologically active natural products, most notably sesquiterpenoids and alkaloids.

Two new hirsutane-type sesquiterpenoids chondrosterins N and O from the marine fungus Chondrostereum sp

The marine fungus Chondrostereum sp. was collected from a soft coral Sarcophyton tortuosum from the South China Sea. This fungus was cultured in glucose-peptone-yeast (GPY) medium and the culture broth was extracted with EtOAc. By the method of ¹H NMR pre-screening and tracing the diagnostic proton signals of the methyl groups, two new hirsutane-type sesquiterpenoids, chondrosterins N and O (1 and 2) were isolated from the metabolite extracts. Their structures were elucidated on the basis of MS, 1D and 2D NMR data.

Photochemical Approaches to Complex Chemotypes: Applications in Natural Product Synthesis

The use of photochemical transformations is a powerful strategy that allows for the formation of a high degree of molecular complexity from relatively simple building blocks in a single step. A central feature of all light-promoted transformations is the involvement of electronically excited states, generated upon absorption of photons. This produces transient reactive intermediates and significantly alters the reactivity of a chemical compound. The input of energy provided by light thus offers a means to produce strained and unique target compounds that cannot be assembled using thermal protocols. This review aims at highlighting photochemical transformations as a tool for rapidly accessing structurally and stereochemically diverse scaffolds. Synthetic designs based on photochemical transformations have the potential to afford complex polycyclic carbon skeletons with impressive efficiency, which are of high value in total synthesis.

Chemoenzymatic Total Syntheses of the Enantiomers of the Protoilludanes 8-Deoxydihydrotsugicoline and Radudiol

Chemoenzymatic and stereoselective total syntheses of the non-natural enantiomeric forms of the recently isolated protoilludane natural products 8-deoxydihydrotsugicoline (1) and radudiol (2) (viz. ent-1 and ent-2, respectively) are reported. The key steps involve the Diels-Alder cycloaddition of cyclopent-2-en-1-one to the acetonide derived from enantiomerically pure and enzymatically derived cis-1,2-dihydrocatechol 3, elaboration of the resulting adduct to the tricyclic ketone 12, and a photochemically promoted rearrangement of this last compound to the octahydro-1H-cyclobuta[e]indenone 13.

Photoinduced Decarbonylative Rearrangement of Bicyclo[2.2.2]Octenones: Synthesis of the Marasmane Skeleton

The marasmane sesquiterpenoid structure can be found in the skeleton of a variety of natural products bearing interesting bioactivity. The unique fused-5,6,3-tricyclic ring structure, in which the rings are cis-fused and the five- and three-membered rings are mutually trans, provides a synthetic challenge for organic chemists. In this work, we took advantage of the photoinduced decarbonylative rearrangement of bicyclo[2.2.2]octenone to develop a new methodology for construction of the highly functionalized fused-5,6,3-tricyclic ring structure in a concise reaction sequence.

Photochemical reactions as key steps in natural product synthesis

Photochemical reactions contribute in a significant way to the existing repertoire of carbon-carbon bond-forming reactions by allowing access to exceptional molecular structures that cannot be obtained by conventional means. In this Review, the most important photochemical transformations that have been employed in natural product synthesis are presented. Selected total syntheses are discussed as examples, with particular attention given to the photochemical key step and its stereoselectivity. The structural relationship between the photochemically generated molecule and the natural product is shown, and, where necessary, the consecutive reactions in the synthesis are illustrated and classified.