Total synthesis of an anticancer norsesquiterpene alkaloid isolated from the fungus Flammulina velutipes

Synthesis of mixed musks via Eschenmoser-Tanabe fragmentation, enyne metathesis and Diels-Alder reaction as key steps

Musk analogues containing different macrocyclic ring systems as well as different annulated ring systems were synthesised by a simple and useful strategy. This strategy includes Eschenmoser-Tanabe fragmentation, enyne metathesis and Diels-Alder reaction as key steps. Starting from easily available (n) macrocyclic ketones, (n + 3) macrocyclic systems were assembled using the basic organic reactions.

Aldehyde to Ketone Homologation Enabled by Improved Access to Thioalkyl Phosphonium Salts

Phosphines were previously unusable as Pummerer-type nucleophiles due to competing redox chemistry with sulfoxides. Here we circumvent this problem to achieve a formal phosphine Pummerer reaction that offers thioalkyl phosphonium salts that, in turn, give rise to diverse vinyl sulfides via Wittig olefinations. Thirty vinyl sulfides are thus prepared from (alkylthioalkyl)triphenyl phosphonium salts and aldehydes. The hydrolysis of these vinyl sulfides offers an efficient and versatile two-step one-carbon homologation of aldehydes to ketones.

Recent Advances in One-Pot Enyne Metathesis Processes for the Preparation of Biologically and Medicinally Relevant Compounds

Enyne metathesis reactions are powerful tools for the preparation of a wide range of synthetic and natural chemical substances with increasing efficiency and environmental sustainability. The driving force of the reaction is the formation of a stable conjugated system, i.e., a diene, which through further functionalization steps can be used for the construction of skeletally complex molecular architectures. These concepts are exploited to design cascade reaction sequences, where multiple rings can be formed in a one-pot fashion by combining metathetic protocols with various chemical transformations. The strong correlation between synthetic organic chemistry and medicinal chemistry prompted us to review the most notable approaches for the synthesis of biologically relevant compounds via enyne metathesis-based one-pot processes. With the aim to provide a modern and practical overview, by taking into consideration the scientific literature on this topic, we have focused the majority of our attention on the research performed in the last decade. This review covers the literature from 2003 to 2020.

1 Introduction

2 Ethylene-Mediated Processes

3 RCEYM/CM and CEYM/RCM Processes

4 Enyne Metathesis/Diels–Alder-Based Processes

5 RCM of Dienynes

6 RCM of Tethered Dienynes

7 Relay Metathesis

8 Ring-Rearrangement Metathesis

9 RCEYM/Transition-Metal-Catalyzed C–C Bond-Forming Processes

10 Conclusions

11 List of Acronyms

Bioactive small secondary metabolites from the mushrooms Lentinula edodes and Flammulina velutipes

Mushrooms have been attracting attention as a source of bioactive compounds for the development of dietary supplements and medicines. Many researchers have reported pharmacological effects of edible mushrooms, and have isolated and identified bioactive substances. Lentinula edodes (shiitake) and Flammulina velutipes (enokitake) are the cultivated edible mushrooms that are popular throughout the world. In L. edodes, polyacetylenes and sulfur compounds have been shown to display antimicrobial activity. In F. velutipes, many types of bioactive terpenes have been reported from mycelium culture filtrate or solid culture substrate. This article reviews the bioactive metabolites of low-molecular weight from L. edodes and F. velutipes.

New frontiers in the transition-metal-free synthesis of heterocycles from alkynoates: an overview and current status

This review highlights the successful utilization of transition-metal-free approaches for the modular assembly of various heterocycles from alkynoates.

Diversity-Oriented Approaches to Polycycles and Heterocycles via Enyne Metathesis and Diels-Alder Reaction as Key Steps

Enyne metathesis (EM) has extensively been used to prepare diverse polycycles and heterocycles. EM in combination with Diels-Alder (DA) reaction has been used to prepare densely functionalized targets in a simple manner. In this mini-review, we discuss the various diversity-oriented approaches reported from our laboratory to prepare a variety of organic frameworks by a synergistic combination of EM and DA reactions. Some of the end products are useful intermediates for the synthesis of complex organic targets.

One-pot quadruple/triple reaction sequence: a useful tool for the synthesis of natural products

Multiple reactions in one pot has always been a useful technique for synthetic organic chemists, as it can minimizes solvent usage, time and the number of purification steps when compared to individual multi-step syntheses. In line with this, here in this perspective we discuss a one-pot quadruple/triple reaction sequence comprising an enyne ring-closing metathesis/cross-metathesis/Diels-Alder/aromatization for the synthesis of natural products setting.