J.-P. Gesson

Enantiodivergent synthesis of (+) and (−) altholactone from D-glucose. Preparation and cytotoxic activity of analogs

Total synthesis of (+)altholactone (goniothalenol), an antitumor pyrone isolated from an unnamed polyalthea species and from goniothalamus giganteus, has been completed in 11 steps from D-glucose using the easily available aldehyde 7. Starting from the same compound or from the related benzoate 24 an enantiodivergent synthesis of (−)1 has also been completed using as the key step an efficient arylation in anhydrous HF. Under these conditions, epimerization at C-8 occurs partially to give the new 8-epi (+)1 or its enantiomer. Most of these pyrones show interesting cytotoxicity in vitro against L1210 leukemia.

A new chiral route toward terpenoids. Annulation of carvone to trans- and cis-fused bicyclic synthons

Abstract Starting from carvone, 1 two consecutive alkylations at C-6 followed by an acid-catalyzed cyclization give new bicyclic ketones which are potentially useful chirons for synthesis of terpenes such as drimanes, labdanes and triterpenes. The stereoselectivity of the second alkylation step which determines the stereochemistry of the ring junction has been studied and the results explained by the model of Tomioka. Several types of products may be formed depending on the acid used and a rearrangement has been observed in one case.

Total synthesis of (+) altholactone (goniothalenol) from D-glucose

Abstract The first total synthesis of the antitumor (+) altholactone is described from D-Glucose.

A general route to 11-deoxyanthracyclines

Abstract Diels-Alder type cycloaddition of unsaturated ketene acetal 5 with various naphtoquinones affords a short and regiospecific access to tetracyclic ketones, key intermediates for the further synthesis of 11-deoxyanthracyclines.

Chiral synthesis of the hydroxy amino acid moiety of AI-77-B

Abstract Chiral synthons of the hydroxy amino acid moiety of AI-77-B, a potent antiulcerogenic compound, have been prepared from the known trifluoroacetamide 3 by reductive opening of the 4,6-O-benzylidene group followed by sequential oxidations at C-1 and C-6. Final oxidation at C-1 (after C-6) to a lactone is shown to proceed in better overall yield than the reverse process.

Approach to the synthesis of annonaceous acetogenins from D-glucose

Abstract The preparation from D-glucose of threo-trans-threo and threo-cis-threo synthons 12 and 13 for the monochiral synthesis of mono (or eventually bis) tetrahydrofuran acetogenins is described. Their structure have been proven by degradation and comparison with a racemic sample of a threo-cis-threo aldehyde prepared by permanganate oxidation of the corresponding diene.

α-N-acyliminium ion - 2-bromoalkene cyclizations.

Abstract The cyclization of α-N-acyliminium ions generated from ethoxylactams 1–3 using trifluoroacetic acid, trifluoromethanesulfonic acid and anhydrous HF affords ketones, bromoalkenes and geminal bromofluoro compounds, respectively. A non concerted process explains these results which demonstrate the high reactivity of the intermediate bromocarbenium ions with different nucleophiles. The unexpected fluorination observed in HF is also observed with simple alkenes which give mixtures of epimeric fluoro derivatives.

Approach to the synthesis of steffimycins preparation and antibacterial activity of (±) 8-demethoxy 7-epi (?) steffimycinone

Abstract Title compound has been prepared in five steps from the readily available 3-chloro 5-hydroxy 7-methoxy 1,4-naphthoquinone, and tested for antibacterial activity.

Diels-Alder reaction of cyclopentadiene and spiroepoxy-2,4-cyclohexadienones

Abstract Diels-Alder reaction of cyclopentadiene with spiroepoxycyclohexadienones obtained by Alder oxidation of salicyl alcohols affords mainly endo-endo adducts. Cope rearrangement of normal-electron-demand adducts and endo-endo inverse-electron-demand addition of 2a with ethylvinyl ether are also shown.

Mevinic acids and analogs : a novel efficient route to chiral synthons from 1,6-anhydro-D-glucose

Abstract 1,6-anhydro-D-glucose is efficiently and regioselectively deoxygenated at C-2 and C-4 by displacement of the corresponding ditosylate with thiophenol followed by Raney Ni hydrogenolysis. This route provides a short access to chirons of the key lactonic moiety of mevinic acids.