Stereoselective synthesis of polyoxygenated atisane-type diterpenoids

Abstract A new stereoselective approach to polyoxygenated atisane-type diterpenes starting from (S)-(+)-carvone is described. The key steps involve an intramolecular Diels–Alder reaction, an unusual intramolecular diazo ketone cyclopropanation of an unsaturated ketone, and a regioselective endocyclic cleavage of a cyclopropyl carbinyl radical as key synthetic steps. The synthesis of the bioactive polyoxygenated atisanes atis-16(17)-en-3,14-dione ( 2 ) and 3R-hydroxy-atis-16(17)-en-2,14-dione ( 3 ) following this approach is presented.

The product of a regiospecific and stereoselective ene-reaction of a polycyclic terpenoid system

The X-ray structure of di­methyl (Z)-[(8aS,2R,4aR,4bR)-8a-methoxy­carbonyl-1,4a,7-tri­methyl-8-oxo-2,3,4,4a,4b,5,8,8a,9,10-deca­hydro­phenanthren-2-yl]-2-butenedioate, C25H32O7, confirmed its relative configuration. The structure shows the bend in the molecular skeleton as found for similar compounds. Weak intermolecular C—H⋯O interactions have been found in the crystal.

Regiospecific and stereoselective ene reaction of the A-ring methylcyclohexene moiety of polycyclic terpenoid systems with dimethyl acetylenedicarboxylate

Polycyclic terpenoid compounds with a methylcyclohexene moiety at the A-ring, such as 1 and 7, give a regio- and stereoselective ene reaction when heated at low temperatures with dimethyl acetylenedicarboxylate. The structure and stereochemistry of the compound formed in the case of 1, e.g. 5, is determined by X-ray analysis.

General Diastereoselective Synthetic Approach toward Isospongian Diterpenes. Synthesis of (−)-Marginatafuran, (−)-Marginatone, and (−)-20-Acetoxymarginatone

This work describes a synthetic approach to the carbocyclic skeleton of isospongian diterpenes that uses the commercially available monoterpene (S)-carvone as a C-ring synthon, which is incorporated into the tetracyclic isospongian framework via a C -> ABC -> ABCD ring annulation strategy using intramolecular Diels-Alder and ring-closing metathesis reactions. This approach has been successfully used to prepare both the title natural isospongians and several nonnatural oxygenated analogues. A preliminary evaluation of the inhibitory activity of the small collection of synthesized isospongians on the mammalian mitochondrial respiratory chain revealed that most were able to inhibit the integra…

ChemInform Abstract: Regiospecific and Stereoselective Ene Reaction of the A-Ring Methylcyclohexene Moiety of Polycyclic Terpenoid Systems with Dimethyl Acetylenedicarboxylate.

Human Endometrial Side Population Cells Exhibit Genotypic, Phenotypic and Functional Features of Somatic Stem Cells

During reproductive life, the human endometrium undergoes around 480 cycles of growth, breakdown and regeneration should pregnancy not be achieved. This outstanding regenerative capacity is the basis for women's cycling and its dysfunction may be involved in the etiology of pathological disorders. Therefore, the human endometrial tissue must rely on a remarkable endometrial somatic stem cells (SSC) population. Here we explore the hypothesis that human endometrial side population (SP) cells correspond to somatic stem cells. We isolated, identified and characterized the SP corresponding to the stromal and epithelial compartments using endometrial SP genes signature, immunophenotyping and char…

Diastereoselective synthesis of antiquorin and related polyoxygenated atisene-type diterpenes

Abstract A diastereoselective approach to polyoxygenated atisene-type diterpenes starting from (S)-(+)-carvone is described. The key steps used in the preparation of the atisene framework are an intramolecular Diels–Alder reaction, an intramolecular diazoketone cyclopropanation, an endocyclic cyclopropane ring cleavage and the regioselective reduction of an allylic bromide by a low-valent chromium species. The synthesis of natural atisanes antiquorin (1), atis-16-ene-3,14-dione (3), atis-16-ene-2,3,14-trione (8) and 3β-hydroxy-atis-16-ene-2,14-dione (9) following this approach is presented. Also described is the synthesis of 18-hydroxy-atis-16-ene-3,14-dione (5), the structure erroneously a…

A unified synthetic approach to trachylobane-, beyerane-, atisane- and kaurane-type diterpenes

A general synthetic approach to the polycyclic carbon skeleton of biogenetically related trachylobane, beyerane, atisane, and kaurane diterpenes from carvone is described. The skeleton of these diterpenes is prepared from a common intermediate, that is, 25, readily prepared from carvone using an IMDA reaction and an intramolecular diazo ketone cyclopropanation of an unsaturated ketone as key steps. The tetracyclic diterpene ring systems are obtained from this key trachylobane-type intermediate through the regioselective reductive cleavage of the cyclopropane ring, after adequate modification of the functionalization around the tricyclo[3.2.1.02,7]octane moiety.

CCDC 626412: Experimental Crystal Structure Determination

Related Article: Antonio Abad, Consuelo Agulló, Ana C. Cuñat, Ignacio de Alfonso Marzal, Antonio Gris, Ismael Navarro, Carmen Ramírez de Arellano|2007|Tetrahedron|63|1664|doi:10.1016/j.tet.2006.11.083