U.Ramdas Nayak

Hydration of longifolene

Unlike the analogous case of camphene, hydration of longifolene with acetic acid-sulphuric acid in dioxane, yielded a strongly laevorotatory tricyclic isomer as the main product. At least three sesquiterpene alcohols resulted as side products, one of which could be correlated with longicamphor.

Studies in sesquiterpenes—XIX : Action of perbenzoic acid on longifolene

Oxidation of longifolene, a mono-olefinic sesquiterpene, with a chloroform solution of perbenzoic acid proceeded to almost two mole consumption of the peracid to furnish a number of products, important ones being an α-ketol, a norketone (longicamphenilone) and the corresponding C14-alcohols. Under certain conditions it has been possible to arrest the reaction at one mole consumption and to isolate longifolene-α-epoxide, which is the major product; some amounts of epimeric longifolaldehydes and longicamphenilone were also formed. Further action of perbenzoic acid on longifolene oxide and longifolaldehydes has been investigated and the results used to interpret the mechanism of abnormal peracid oxidation of longifolene.

Studies in sesquiterpenes—XXI : Longifolic acids

Abstract The nature and inter-relationship of longifolic acids have been clarified. There are, in fact, three C 15 monocarboxylic acids derived from longifolene and not two. The acid, described as longifolic acid and obtained in a state of purity for the first time by Naffa and Ourisson, has been shown as not representing the thermodynamically less stable epimer of the well-characterized isolongifolic acid but to possess a different structure, and has been termed ψ-longifolic acid. The less stable epimer, longifolic acid, has been obtained pure for the first time.

Studies in sesquiterpenes—XX : Acetoxymethylation of longifolene☆

Longifolene in Prins reaction with formaldehyde yielded the expected ω-acetoxymethyl longifolene, which was transformed into a number of interesting derivatives. Configuration of the Prins product has been arrived at by NMR measurements. The UV absorption of these derivatives show a considerable bathochromic shift with respect to those in the camphene series and this could be attributed to the slight twisting of the ethylenic linkage in longifolene and its derivatives.