Lactone Function Research Articles

Mass spectra of staphylomycin S components and of related cyclodepsipeptide antibiotics

AbstractThe electron‐impact induced fragmentation of staphylomycin S (I) and related cyclodepsipeptides (II to V) is mainly initiated by elimination of an azomethin molecule (RCHNR′), i.e. 1,2‐dehydro‐4‐oxopiperidine for I and II, 1,2‐dehydro‐4‐hydroxy‐piperidine for III and IV, and an unknown hydroxy‐1,2‐dehydro‐4‐oxopiperidine for VI. Cyclic imino acids, e.g. a pipecolic acid derivative for I to IV and 4‐hydroxyproline for etamycin (IX) preferentially trigger this reaction. Clearcut evidence for the amino acid sequence is given by the mass spectra of the linear peptides obtained from I, V and IX by alkaline hydrolysis of the lactone function and esterification of the carboxy group.

Experiments towards a synthesis of antheridiol: a synthesis of biologic-ally active material

A conversion of diosgenin into a product exhibiting the biological activity of antheridiol (but at a lower level) is described. The product is either an active stereoisomer of antheridiol, or, more probably, a stereoisomer con-taminated with antheridiol. In the course of the synthesis novel conditions were used for (i) the reduction of a hindered ketone in the presence of ester and lactone functions and (ii) an oxidative demethoxycarbonylation reaction to introduce a double bond.

Electron‐transfer polymers. XL. Redox polyamides

AbstractBy condensing a hydroquinone bis‐lactone of 1,4‐dihydroxybenzene‐2,5‐bis(ethyl‐2′‐carboxylic acid) with diamines such as hexamethylene diamine, piperazine, 4‐aminoethylpiperidine, or 1,3‐di‐(4′‐piperidinyl) propane, redox polyamides can be prepared. The lactone functions protect the hydroxyl groups until the polymerization occurs at which point, due to the opening of the lactone rings, free hydroquinone hydroxyls appear. The resulting polymer is oxidizable. When the oxidized polymer is reduced the viscosity is higher than that of the original reduced polymer.

LYCOPODIUM ALKALOIDS: XVI. ANNOTINE

Annotine, C16H21O3N, is shown to be pentacyclic and to contain a tertiary hydroxyl group, a lactone function, a tertiary nitrogen atom, and a dialkylated double bond. The position of the double bond and the tertiary hydroxyl group relative to the nitrogen atom has been established by Emde degradation of annotine methiodide. The presence of a lactone function is inferred from the reduction of annotine to dihydroannotinol, a hemiacetal, which reacts with 1 mole of ethyl mercaptan. The reduction of the lactone to a diol in an annotine derivative has been carried out. The chemical studies and the examination of annotine and its derivatives by modern instrumental methods allow the assignment of a plausible structure to the alkaloid.