Pierre Mangeney

Chiral phosphorus ligands for the asymmetric conjugate addition of organocopper reagents

The asymmetric conjugate addition of medium order alkyl cuprate reagents. R5Cu3Li2, to 2-cyclohexen-1-one. 2-cyclopenten-1-one and 2-cyctohepten-1-one, with the help of phosphorus ligand B*, is described. 3-Alkyl substituted cyclohexanones are obtained in essentially optically pure form. The same chiral ligand, associated with CuI, in catalylic amount (10%), allows the asymmetric conjugate addition of Et2Zn to 2-cyclohexen-1-one.

Asymmetric conjugate addition of diethyl zinc to enones with chiral phosphorus ligands derived from TADDOL

The asymmetric conjugate addition of diethyl zinc to cyclohexen-2-one, chalcone and benzalacetone was studied with 0.5% copper (II) triflate and 1% chiral phosphorus ligands derived from TADDOL. Among the several ligand tested, the cyclic phosphite obtained with 1S,2R phenylcyclohexanol gave up to 96% ee of conjugate adduct to cyclohexenone.

Enantioselective conjugate addition of diethylzinc using catalytic silver(I) diaminocarbenes and Cu(OTf)2

Abstract Chiral silver(I) diaminocarbenes act as efficient carbene transfer agents to copper salts. The catalytic species, active in the conjugate addition of diethylzinc to cyclohexenone, is prepared easily at room temperature in various solvents by simply mixing the silver carbene and Cu(OTf)2. This method avoids the use of strong bases and polar solvents to generate the carbene. The chiral diaminocarbene–copper catalyst, formed in situ, shows a strong accelerating effect and gives enantiomeric excesses up to 23%.

Diastereoselective syn or anti opening of propargylic epoxides. Synthesis of α-allenic alcohols

Abstract Propargylic epoxides easily react with Grignard reagents and catalytic amounts of copper(I) salt to afford α-allenic alcohols. The reaction is highly diastereoselective and its stereochemical outcome ( syn or anti isomer) can be fully controlled. The syn diastereomer, probably arising through an addition-elimination mechanism, is better obtained with RMgCl and copper(I) bromide, whereas the anti diastereomer, is better obtained with RMgBr and a complexed copper(I) salt. With RLi and a catalytic amount of copper salt, phenethynyl cyclohexene oxide reacts through reductive lithition, affording, stereoselectivety, an allenyl lithium reagent.

Asymmetric conjugate addition of diethyl zinc to enones with tartrate chiral phosphite ligands

The asymmetric conjugate addition of diethyl zinc to cyclohexen-2-one occurs with 0.5% copper (II) triflate and 1 % chiral phosphite. Cyclic phosphites derived from various tartrates gave a moderate enantiomeric excess. The nature of the exocyclic substituent of the dioxaphospholane ring is important, but the chiral induction is imposed by the tartrate framework.

Enantioselective catalytic reduction of ketones using C2-symmetric diamines as chiral ligands.

Abstract The catalytic enantioselective reduction of various prochiral ketones is reported using C 2 -symmetric diamines as ligands. Up to 99% e.e. at 100% conversion are obtained.

Acceleration of the conjugate addition of diethyl zinc to enones by either Cu(OTf)2 or trivalent phosphorus ligands

The conjugate addition of diethyl zinc to enones under copper catalysis occurs well with copper (II) triflate. Other copper salts need a phosphine or phosphite ligand to be efficient. The best combination is copper (II) triflate and triethyl phosphite. A very small amount of copper (II) triflate (0.5%) and triehyl phosphite (1%) are enough for high yields.

A new class of antitumor compounds: 5'-nor and 5',6'-seco derivatives of vinblastine-type alkaloids.

isopropylpenty1)triphenylphosphonium bromide, 71436-81-2; (3tetrahydropyranyloxypropy1)triphenylphosphonium bromide, 70665-02-0; isohexyltriphenylphosphonium bromide, 70240-41-4; (methoxymethy1)tripheriylphosphonium chloride, 4009-98-7; (3tetrahydropyranyloxyprolpylidene) triphenylphosphorane, 71436-82-3; [ 3(2-methyl-1,3-dioxolain-2-yl)propylidene] triphenylphosphorane, 3054-93-1; (4-methylpentylidene)triphenylphosphorane, 54517-55-4; 3-methylbutylidenetriphenylphosphorane, 39110-24-2; methoxyJ . Org. Chem., Vol. 44, .No. 22, 1979 3765

Resolution and determination of enantiomeric excesses of chiral aldehydes via chiral imidazolidines

Enantiomeric purity of chiral aldehydes was determined by NMR analysis of derived imidazolidines. The diastereomeric imidazolidines were easily separted by silica gel column and converted into enantiomerically pure aldehyde by acid hydrolysis.

Synthesis of chiral silver(I) diaminocarbene complexes from (R,R)-4,5-di-tert-butylimidazoline

Abstract A preparation of chiral silver(I) diaminocarbene complexes was developed by treatment of imidazolinium salts derived from ( R , R )-4,5-di- tert -butylimidazoline with silver(I) oxide. Complexes having the chirality on the heterocycle and methyl, benzyl or picolyl groups on the nitrogen atoms have been prepared. We also performed the synthesis of diaminocarbenes having in addition the chiral ( S )-1-phenylethyl moiety on the nitrogen atoms. X-ray structures of two of these carbenes ( N , N ′-dimethyl and N , N ′-dibenzyl) are presented. Several methods for the preparation of imidazolinium salts are described.