Philippe Bertus

Cyclopropenylcarbinol Derivatives as New Versatile Intermediates in Organic Synthesis: Application to the Formation of Enantiomerically Pure Alkylidenecyclopropane Derivatives

The copper-catalyzed carbomagnesiation (or hydrometalation) reaction of chiral cyclopropenylcarbinol derivatives, obtained by means of a kinetic resolution of secondary allylic alcohols, leads to an easy and straightforward preparation of enantiomerically pure alkylidenecyclopropane derivatives. The reaction mechanism is composed of a syn-carbometalation followed by a syn-elimination reaction. To gain further insight into the reaction mechanism of the carbometalation, the diastereoselective formation of cyclopropylcarbinol was also achieved and was found to be very sensitive to the nature of the organometallic species used for the addition reaction. Cyclopropylcarbinol could also be prepared through a diastereoselective reduction of cyclopropenylcarbinol derivatives. Finally, functionalization of enantiomerically enriched cyclopropenylcarbinols into the corresponding acetate or phosphinite derivatives leads, under mild conditions, to various enantiomerically pure heterosubstituted alkylidenecyclopropanes.

The first direct coupling of 1-trialkylsilyl-1-alkynes with vinyl triflates; a new access to enynes

Abstract 1-Trialkylsilyl-1-alkynes can be directly coupled with vinyl triflates in the presence of TBAF, 3H 2 O and a catalytic amount of AgI and Pd(PPh 3 ) 4 . Functionalized enynes can thus be obtained in good to excellent yields without prior deprotection of the alkyne.

Solvent-free direct reductive amination by catalytic use of an organotin reagent incorporated on an ionic liquid.

An organotin reagent supported on an ionic liquid was used as a highly effective catalyst (down to 0.1 mol%) for the direct reductive amination of aldehydes and ketones using PhSiH3; this solvent-free method facilitates purification of the products, thus minimizing the contamination by tin.

SILVER SALTS AS NEW CATALYST FOR COUPLING REACTIONS; SYNTHESIS OF EPOXYENYNES

Abstract The coupling of ethynyloxiranes with alkenyl triflates have been achieved by treatment with the following association of catalysts: silver salt and tetrakis(triphenylphosphine) palladium. This new set of catalysts allowed for the direct formation of epoxyenynes in rather good yields.

Titanium-mediated synthesis of bicyclic cyclopropylamines from unsaturated nitriles

Here we report an easy synthesis of bicyclic primary cyclopropylamines directly from unsaturated nitriles. The described reaction involves Ti(II)-mediated intramolecular coupling of alkene and nitrile moieties.

Synthesis of enynes and epoxyenynes by coupling: use of a new set of catalysts based on Pd–Ag salts

Abstract The new couple of catalysts Pd(PPh 3 ) 4 and AgI are very efficient for the coupling of vinyltriflates and terminal alkynes in the presence of a bulky amine in dimethylformamide at room temperature. Enynes and epoxyenynes are obtained in good to excellent yields. As illustrated with several examples, a wide variety of functional groups are well tolerated in the described conditions. Silver acetylides have been proposed as intermediate in this reaction.

Diene-titanium complexes as synthetic intermediates for the construction of three- or five-membered carbocycles.

It has been shown that diene-titanium complexes exhibit substrate-dependent 1,2- or 1,4-dicarbanion reactivity. On this basis, 3-cyclopentenylamines and spiro-vinylcyclopropane lactams were easily prepared by using homoallylic Grignard reagents, Ti(O-i-Pr)4, and nitriles or cyanoesters, respectively.

Synthesis of enynes related to neocarzinostatine using the new PdAg catalyzed coupling reaction

Abstract Both E and Z isomers of 2-triflyloxymethylene cyclopentanone, 1 and 2 respectively, have been coupled with various functionalized acetylenes in the presence of the Pd Ag set of catalysts. This method provides a rapid and stereoselective access to various E or Z 2-(alkynyl)methylene cyclopentanone derivatives, which are promising and versatile intermediates toward NCS-Chrom and analogs.

Studies on the titanium-catalyzed cyclopropanation of nitriles.

The Ti-mediated reaction of Grignard reagents with nitriles was investigated with sub-stoichiometric amounts of titanium isopropoxide. Cyanoesters were converted to spirocyclopropanelactams in good yields using as low as 0.05 eq of Ti(O(i)Pr)4. Under similar conditions, cyanocarbonates led to spirocyclopropane oxazolidinones and/or aminocyclopropylcarbinols. A very short synthesis of the naturally occurring aminocyclopropanecarboxylic acid illustrates the usefulness of this methodology.

Pd/Ag-Catalyzed Direct Coupling of 1-Trimethylsilyl Alkynes with Vinyl Triflates

The commercially available tetrabutylammonium fluoride trihydrate is able to promote the cross-coupling of vinyl triflates with 1-trimethylsilylalkynes in the presence of a catalytic amount of tetrakis(triphenylphosphane)palladium and silver iodide.