Jacques Salaün

Cyclopropane Derivatives and their Diverse Biological Activities

Natural and synthetic cyclopropanes bearing simple functionalities are endowed with a large spectrum of biological properties ranging from enzyme inhibitions to insecticidal, antifungal, herbicidal, antimicrobial, antibiotic, antibacterial, antitumor and antiviral activities.

α-Alkylation of acyclic amino acids with self-reproduction of the Center of Chirality. A new route to (S)-(+)-α-alkylated aspartic acids.

Abstract The amino acids 1a - d (alanine, phenylalanine, valine and methionine) are alkylated by ethyl bromoacetate, with inversion of configuration, to provide readily with high stereoselectivity the α-alkylated aspartic acids 9a - d through the chiral enolates 7a - d of the trans (2R,4S) oxazolidinones 6a - d , major products of cyclization of the imines 5a - d with benzoyl chloride.

Anhydrous ferric chloride adsorbed on silica gel induced ring enlargement of tertiary cyclobutanols : Synthesis of isolaurolene and derivatives, campholenic ether and (±) cuparene

Abstract The reagent obtained by mixing anhydrous FeCl 3 and silica gel induced, in dry medium, dehydration and specific C 4 → C 5 ring enlargement of tertiary cyclobutanols, cyclization of olefinic alcohols and cleavage of tetrahydropyranyl ethers.

The virtue of methylenecyclopropane terminators in intramolecular Pauson-Khand reactions

Abstract 6-Cyclopropylidene-1-hexynes like 2 , e. g. prepared via palladium(0)-catalyzed substitution of 1-ethenyl cyclopropyl sulfonates 1 , undergo an intramolecular Pauson-Khand reaction both efficiently and regioselectively.

Enantioselective construction of spiro{cyclopropane-14′-bicyclo[3.3.0]oct-1-en-3-ones}

Abstract Intramolecular Pauson-Khand reactions of 1,6-enynes 3a–c with a methylenecyclopropane terminator and a chiral acetal moiety adjacent to the triple bond gave spiro{cyclopropane-1,4′-bicyclo[3.3.0]oct-1-en-3-ones} 5a–c in good yields with a diastereoselectivity of up to 6.4:1. The major diastereomer of 5b was converted to enantiomerically pure bicyclo[3.3.0]octane-3,8-dione 8 , which showed a negative peak at 287 nm in the CD curve, consistent with an assumed (5 R ) configuration.

Palladium (O) catalyzed tandem alkylation and SN′ cyclization of 1,4-dichlorobut-2-ene by the N-(diphenylmethylene)acetonitrile. A stereoselective synthesis of 1-aminocyclopropanecarboxylic acids

Abstract Racemic coronamic acid has been prepared with 100% diastereoselectivity from one pot palladium (O) catalyzed alkylation and S N′ cyclization of 1,4-dichlorobut-2-ene by the benzophenone Schiff base of aminoacetonitrile.

Anhydrous ferric chloride dispersed on silica gel induced ring enlargement of tertiary cycloalkanols. II: A convenient homologation of cycloalkanones, preparation of spiro systems and propella-γ-lactones

Abstract The reagent obtained by mixing anhydrous FeCl3 and silica gel induced, in the lack of any solvent, dehydration of tertiary cycloalkanols, specific C4→C5 and C5 →C6 enlargement, formation of spiro compounds and propella-γ- lactones and cleavage of tetrahydropyranyl ethers.

Optically active 2-vinylcyclobutanones

Abstract Enzymatic resolution of dimethyl 2-methylsuccinate, acyloin cyclization and base induced ring contraction provided 1-hydroxycyclopropanecarboxylic acids with high optical purity (>95% e.e). Their derivatives opened a regio- and stereoselective way to optically active 2-vinylcyclobutanones (>84-90% e.e), providing useful building blocks for further ring expansions.

Optically active α-alkylsuccinates from the stereoselective alkylation of chiral imide enolates.

Abstract The chiral oxazolidinones 1 and 2 were alkylated by methyl bromoacetate, then subsequent removal of the chiral auxiliary provided readily with high stereoselectivity the α-alkylated succinates 7 and 8 . Acyloin condensation and bromination gave the optically active α-t-butylcyclobutanedione 10 .

Titanium-Mediated Diastereoselective Formation of (E)- or (Z)-2-Substituted 1-Vinylcyclopropanols: Scope and Limitation, Applications

Titanium-mediated cyclopropanation of α,β-unsaturated esters failed to provide 1-vinylcyclopropanol derivatives in useful yields, but (E)-2-substituted-1-vinylcyclopropanols were formed diastereoselectively from O-protected β-oxo- and β-halo esters, with the allylic double bond being created subsequently (Knoevenagel condensation or dehydrohalogenation). Titanium-mediated cyclopropanation of homoallyl alk-2-enoates, on the other hand, directly provided the corresponding Z diastereomers. Palladium(0)-catalysed azidation of their sulfonic esters (tosylate, mesylate), azide reduction, and subsequent double bond cleavage afforded (E)- or (Z)-2-alkyl-2,3-methanoamino acids, although improvements are required to perform the total asymmetric syntheses of molecules with three membered-rings by these methods. (© Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)