Mark J. Ackland

Structures of the cephalosporolides B–F, a group of C10 lactones from Cephalosporium aphidicola

The structures of the pentaketides lactones, the cephalosporolides B–F, were elucidated by a combination of spectroscopic, chemical, and X-ray analyses.

An oxygen-18 study of the biosynthesis of the diterpenoid, aphidicolin in cephalosporium aphidicola☆

Abstract Deuterium labelling has been used to demonstrate that the loss of the 17-CH 2 OH forms the initial fragmentation in the mass spectrum of aphidicolin. The results have been used to establish the site (C-16) of incorporation of 18 O from H 2 18 O in the biosynthesis of aphidicolin by the fungus, Cephalosporium aphidicola .

Studies in terpenoid biosynthesis. Part 30. The acetate and mevalonate labelling patterns of the diterpenoid, aphidicolin

The 13C n.m.r. spectra of aphidicolin and its derivatives have been assigned. The enrichment and coupling patterns of aphidicolin biosynthesized from [1-13C]-, [2-13C]-, and [1,2-13C2]-acetate were determined and used to define the constituent isoprene units. The numbers of 2- and 5-mevalonoid hydrogen atoms incorporated into aphidicolin were determined by 3H labelling. The generation of2H–13C coupling which was observed in the 2H n.m.r. spectrum of aphidicolin biosynthesized from [4-2H2,3-13C] mevalonic acid, has established the migration of a 9β-hydrogen atom to C-8 during the biosynthesis.

Studies in terpenoid biosynthesis. Part 38. The role of an 16β,17-epoxyaphidicolane in the minor biosynthetic pathway leading to aphidicolin

The hydroxylation of [15-2H, 17-2H3]aphidicolane-3α,16β,18-triol at C-17 in the biosynthesis of aphidicolin is shown to involve an isotope effect whilst there is no effect in the incorporation of [15-2H, 17-2H2]aphidicol-16-ene-3α,18-diol suggesting that the transformation of the 16-ene involves epoxidation and hydrolysis rather than hydration and hydroxylation. Feeding experiments suggest that the 16β,17-epoxyaphidicolane-3α,18-diol is involved in this transformation.

Studies in terpenoid biosynthesis. Part 32. The incorporation of aphidicolan-16-ene and aphidicolon-16β-ol into the diterpenoid aphidicolin by the fungus Cephalosporium aphidicola

The preparation of [17-14C]aphidicol-16-ene and [17-14C]aphidicolan-16β-ol and their incorporation into aphidicolin by Cephalosporium aphidicola to the extent of 0.09 and 7.9% respectively, is described.

STEREOCHEMICAL FACTORS ASSOCIATED WITH THE REARRANGEMENT OF (2-ETHYL-1-AZABUTA-1,3-DIENE)TRICARBONYLIRON(0) COMPLEXES

Abstract Reaction of (2-ethyl-1,4-diphenyl-1-azabuta-1,3-diene)tricarbonyliron(0) 4 and (2-ethyl-1-benzyl-4-phenyl-1-azabuta-1,3-diene)tricarbonyliron(0) 7 with lithium diethylamide leads to selective formation of the corresponding endo (1-methyl-2-amino buta-1,3-diene)tricarbonyliron(0) complexes 5 and 8 , respectively. In each case there is no evidence for the exo complexes 6 and 9 .

The structure of thiobiscephalosporolide A, A dimeric pentaketide macrolide from Cephalosporium aphidicola

The isolation, structure elucidation, and some chemical transformations of the dimeric macrolide, thiobiscephalosporolide A, are reported.

Studies in terpenoid biosynthesis. Part 35. Biosynthetic sequences leading to the diterpenoid aphidicolin in Cephalosporium aphidicola

[17-14C]-Labelled samples of 18-hydroxyaphidicol-16-ene,3α, 18-dihydroxyaphidicol-l6-ene, 16β,17 and 16β,18-dihydroxyaphidicolane, and 3α, 16β, 18- and 16β,17,18-trihydroxyaphidicolane have been prepared from aphidicolin and shown to be incorporated into aphidicolin by Cephalosporium aphidicola to the extent of 0.86, 16.4, 3.5, 20.5, 52.6, and 16.9%, respectively. These results suggest that although the major pathway of aphidicolin biosynthesis involves the 16β-alcohols, the 16-enes may also be utilized whilst a metabolic grid relationship may exist between the variously hydroxylated 16β-alcohols.

Structure of thiobiscephalosporolide-A, a macrolide from Cephalosporium aphidicola

The structure of thiobiscephalosporolide has been elucidated by a combination of chemical, spectral, and X-ray studies.

A mild method for the conversion of 1,3-glycols into unsaturated alcohols

Some transformations of 1,3-glycols utilizing dimethylformamide dimethyl acetal have been examined with the diterpenoids aphidicolin and foliol and some steroids as substrates. Axial alcohols with a suitably disposed trans hydrogen atom undergo an elimination reaction to give the formate of an unsaturated alcohol via the quaternary salt of the cyclic formamido acetal.