M.J. Sexmero

Synthesis and absolute configuration of three natural ent-halimanolides with biological activity

The first three natural ent-halimanolides known until now have been synthesized from ent-halimic acid. Their structure have been confirmed as well as their absolute configurations established. Bestmann methodology has been used for the synthesis of butenolides and for the γ-hydroxybutenolides synthesis the Boukouvalas method has been employed. Biological testing has been carried out on these compounds.

Synthesis and absolute configuration of (-)-chettaphanin I and (-)-chettaphanin II

An efficient synthesis of chettaphanin I and II has been achieved from ent-halimic acid. The absolute configuration of the natural products was established by nOe experiment and by X-ray analysis of chettaphanin II.

Synthesis and absolute configuration of (−)-chettaphanin II

Abstract An efficient synthesis of chettaphanin II has been achieved from ent -halimic acid. The absolute configuration of the natural product was established and corroborated by X-ray analysis of chettaphanin II.

Diterpenic α- and β-hydroxybutanolides with antifeedant activity: semisynthesis and absolute configuration†

Abstract Two series of ent-halimanolides (15,16-olides and 16,15-olides), analogues of biologically active diterpene lactones, were synthesized starting from ent-halimic acid methyl ester. The absolute configuration was determined by CD spectroscopy and corroborated by X-ray analysis. Antifeedant testing has been carried out on these compounds.

Minor diterpenoids from Halimium viscosum

Two new diterpenic acids with an ent-halimane skeleton have been isolated from the aerial parts of Halimium viscosum (Villarino de los Aires chemotype) and separated as methyl esters. These diterpenes were 13-oxo-14, 15-dinor-1(10),11E-ent-halimadien-18-oic acid and 15-hydroxy-1(10),13Z-ent-halimadien-18-oic acid.

Isofregenedadiol: A novel diterpenic diol from Halimium viscosum

Abstract One of the chemotypes of Halimium viscosum—La Fregeneda—provided a new natural product with a rearranged skeleton. The new bicyclic diol possesses an aromatic ring B and its structure has been determined on the basis of 1H, 13C and 2D NMR (1H13C HETCOR and 1H13C long range inverse detected HMBC) studies.

Synthesis of an ent-Halimanolide from ent-Halimic Acid

An efficient synthesis of ent-halimanolide 2 (15,16-epoxy-12-oxo-ent-halima-5(10),13(16),14-trien-18,2β-olide), from ent-halimic acid has been achieved, corroborating the structure of the natural compound and establishing its absolute configuration.

Synthetic Studies Towards the ent-Labdane Diterpenoids: Rearrangement of ent-Halimanes

For the first time ent-labdanes have been synthetised starting from ent-halimic acid, following a route that is the reverse of the biosynthetic one leading to the former compounds.