Triterpenoids and a diterpene from Euphorbia iberica

Microbial membranes exhibit remarkable diversity in lipid composition, reflecting evolutionary adaptations to various environmental conditions. The three domains of life—Bacteria, Archaea, and Eukarya—synthesize membrane lipids through distinct biosynthetic pathways, leading to fundamental structural differences that impact membrane stability, function, and adaptability.Fatty Acid-Based Lipids in Bacteria and EukaryaBacteria and eukaryotes share a common fatty acid biosynthesis...

Structure and Bonding
Ethers are organic compounds with an ether functional group which is characterized by an oxygen atom connected to two — identical or different — alkyl, aryl, or vinyl groups. The C–O–C linkage in dimethyl ether — the simplest ether — has an approximately tetrahedral bond angle of 110.3 degrees. The oxygen atom is sp3- hybridized, with the C–O distance being about 140 pm.
Classification of Ethers
Based on their attached substituent...

Cyclic ethers are heterocyclic compounds with an oxygen atom in the ring along with carbon atoms. They are named depending on the number of carbon atoms present in their ring system. Cyclic ethers with a three-membered ring system are called “oxirane”, four-membered ring systems as “oxetane”, five-membered ring systems as “oxolane”, and six-membered ring systems as “oxane”. The cyclic structure of these rings imposes angle strain, and this strain...

Introduction
Conjugated dienes are compounds characterized by the presence of alternating double and single bonds. In a conjugated system like 1,3-butadiene, the unhybridized 2p orbital on each carbon overlaps continuously, allowing the π electrons to be delocalized across the entire molecule. In contrast, this type of overlap does not occur in cumulated and isolated dienes, such as 2,3-pentadiene and 1,4-pentadiene, respectively. Instead, the π electrons remain localized between the double...

Cycloheptatriene is a neutral monocyclic unsaturated hydrocarbon that consists of an odd number of carbon atoms and an intervening sp3 carbon in the ring. The three double bonds in the ring correspond to 6 π electrons, which is a Huckel number, and therefore satisfies the criteria of 4n + 2 π electrons. However, the intervening sp3 carbon disrupts the continuous overlap of p orbitals. As a result, cycloheptatriene is not aromatic.
Removing one hydrogen from the intervening CH2 group...

In general, the term ‘aromatic’ indicates a pleasant smell or fragrance from fresh flowers, freshly prepared coffee, etc. In the early history of organic chemistry, many benzene derivatives were isolated from the pleasant odor oils of the plants. For example, vanillin was isolated from the oil of vanilla, methyl salicylate from the oil of wintergreen, and cinnamaldehyde from the oil of cinnamon. They all had a pleasant odor; hence the name aromatic was given.
In 1825, Faraday isolated...