Olivier Piva

New perfluoroalkylated cinchona derivatives: synthesis and use in base-catalysed Diels–Alder reactions

Abstract Perfluorinated cinchona derivatives 1 – 4 were synthesised starting from commercially available compounds. They were tested in fluorous solvents in base catalysed Diels–Alder reactions and delivered adducts with ee up to 40%.

Synthesis and applications of the first polyfluorous proline derivative

Abstract Starting from trans-4-hydroxy- l -proline, a polyfluorinated proline derivative having a fluorine content of 54% has been prepared. It has been tested as a catalyst in the aldol reaction between p-nitrobenzaldehyde and acetone with 73% ee in BTF and in copper(I)-catalyzed allylic oxidation of cyclohexene with 20% ee in HFIP.

Total synthesis of bistramide A and its 36(Z) isomers: differential effect on cell division, differentiation, and apoptosis.

The total synthesis of bistramideu2005A and its 36(Z),39(S) and 36(Z),39(R) isomers shows that these compounds have different effects on cell division and apoptosis. The synthesis relies on a novel enol ether-forming reaction for the spiroketal fragment, a kinetic oxa-Michael cyclization reaction for the tetrahydropyran fragment, and an asymmetric crotonylation reaction for the amino acid fragment. Preliminary biological studies show a distinct pattern of influence of each of the three compounds on cell division, differentiation, and apoptosis in HL-60 cells, thus suggesting that these effects are independent activities of the natural product.

Enantioselective synthesis of 2-sulfenylated aldehydes : alkylation of sulfenylated acetaldehyde SAMP-hydrazones

Abstract A practical and efficient enantioselective synthesis of 2-sulfenylated aldehydes (S)- 6 is described, based on the α-alkylation of sulfenylated acetaldehyde SAMP hydrazones (S)- 4 , easily prepared from bromoacetaldehyde diethylacetal 1 , thiols and (S)-1-amino-2-methoxymethyl-pyrrolidine (SAMP). A chemoselective oxidative cleavage of the intermediate SAMP hydrazones (S,S)- 5 with ozone gives rise to the title compounds (S)- 6 in good overall yields and high enantiomeric excesses of up to 97%.

A short access to 3-hydroxy-4-hydroxymethyltetrahydrofurans: application to the total synthesis of amphiasterin B4.

The first total synthesis of amphiasterin B4, a secondary metabolite previously isolated from Plakortis quasiamphiaster has been achieved. The core structure has been reached according to a highly stereoselective one-pot epoxidation/cyclization of an unsaturated diol. This substrate can be prepared from beta,gamma-unsaturated diesters readily available from the organocatalyzed protonation of a transient dienol generated by UV irradiation of corresponding alpha,beta-unsaturated isomers.

Anionic versus photochemical diastereoselective deconjugation of diacetone D-glucose α, β-unsaturated esters

Abstract Deconjugation of diacetone d -glucose α,β-unsaturated esters has been conducted by deprotonation using NaHMDS with HMPA as co-solvent followed by stereoselective protonation at low temperature. High selectivities (>95%) were obtained with α-methyl linear compounds.

Application of chiral tethers to intramolecular [2+2] photocycloadditions: synthetic approach to (−)-italicene and (+)-isoitalicene

Abstract A synthetic approach to (−)-italicene and (+)-isoitalicene, sesquiterpenes which possess the rare tricyclo[5.4.0.0 1,5 ] undecane skeleton has been developed using as key step a highly regio- and diastereoselective [2+2] photocycloaddition. ( S )-Lactic acid plays the role of a chiral removable tether group during the building of the cyclobutane ring.

Structure and Synthesis of Anhydrobisfarnesol from Euphorbia lateriflora and Asymmetric Synthesis of (R)-Sesquilavandulol

Abstract Anhydrobisfarnesol has been isolated from the latex of Euphorbia lateriflora and assigned structure 4 on the basis of its spectroscopic properties. Its structure has been confirmed by synthesis using a photochemical isomerisation procedure. A similar approach has been used for the total synthesis of (R)-sesquilavandulol.

Tandem Michael–Wittig–Horner Reaction: Application to the Synthesis of Bisabolanes

Abstract Bisabolane derivatives have been synthesized from para-substituted cinnamaldehydes according to a tandem Michael–Wittig–Horner reaction. This sequence was applied to a short access to (+/−)-ar-turmerone.

Tandem Michael−Wittig−Horner Reaction: One-Pot Synthesis of δ-Substituted α,β-Unsaturated Carboxylic Acid Derivatives − Application to a Concise Synthesis of (Z)- and (E)-Ochtoden-1-al

A new tandem Michael−Wittig−Horner reaction has been developed to produce in high yields δ-substituted α,β-unsaturated esters, amides and lactones. The reaction has been successfully applied to a concise synthesis of (E)- and (Z)-ochtoden-1-als, components of the male sex pheromone of boll weevil from 3-methylcyclohex-2-en-1-one.