Didier Nuel

Palladium and phase transfer catalyzed carbonylation of propargyl derivatives

Abstract The palladium catalyzed carbonylation of propargyl derivatives in the presence of phosphines and under phase transfer conditions leads to the formation of allenic acids and olefinic diacids with good yields and very high selectivity.

Secondary Phosphine Oxides as Multitalented Preligands En Route to the Chemoselective Palladium‐Catalyzed Oxidation of Alcohols

Secondary phosphine oxides O=PHR2 (SPOs) were identified as multitalented preligands for the chemoselective Pd‐catalyzed oxidation of alcohols by a hydrogen‐abstracting methodology. SPOs were found to promote the hydrogen‐abstraction step as well as hydrogen transfer to a Michael acceptor by generating a putative active H−Pd species. The catalytic system operates under neutral conditions and was proven to be compatible with various electrophilic and nucleophilic functionalities within the substrates as well as water‐ and air‐sensitive functional groups.

Oxidative addition of Ph3PCHCHO at a triosmium cluster with cleavage of C–;H bonds: crystal structures of two isomers containing the new ligands Ph3PCCHO and Ph3PCHCO, respectively

Rapid oxidative addition of Ph3PCHCHO at [Os3(CO)10(MeCN)2] gives the isomers [Os3H(µ-Ph3PCCHO)(CO)10](1) and [Os3H(µ-Ph3PCHCO)(CO)10](2)(X-ray structures reported) which decarbonylate to give the clusters containing triply-bridging ligands: [Os3H(Ph3PCCHO)(CO)9](3), [Os3H2(C6H4PPh2CCHO)(CO)8](5), and [Os3H(Ph3PCHCO)(CO)9](4)(as two isomers).

Effect of cyclodextrins on the rhodium-catalysed hydrogenation of unsaturated carboxylic acids in water

Abstract Addition of cyclodextrin to the well-known RhCl3/TPPTS (trisulfonated triphenylphosphine) hydrogenation catalytic system leads to high selectivities in the hydrogenation of unsaturated carboxylic acids in water. The presence of both cyclodextrin and sulfonate ions is required to obtain high selectivities.

Cobalt(III)-catalysed C–H allylation with vinylaziridines

A cobalt-catalysed C–H allylation of aromatic and heteroaromatic compounds with vinylaziridines is described. This transformation occurring under mild reaction conditions proceeds through C–H activation, carbon–carbon double bond insertion and β-nitrogen elimination. Its scope and limitations have been investigated and a synthetic application of products has been achieved.

Oxidative addition of Ph3PCHCHO to [Os3(CO)10(MeCN)2]

(Triphenylphosphoranylidene)ethanal (Ph3PCHCHO) rapidly adds at room temperature or below to [Os3(CO)10(MeCN)2] to give the light-sensitive isomeric clusters [Os3(µ-H)(µ-Ph3PCCHO)(CO)10]1(39%) and [Os3(µ-H)(µ-Ph3PCHCO)(CO)10]2(34%) derived by C–H bond cleavage at the CHCHO and CHCHO positions respectively. Rates of oxidative addition are higher than for aldehydes or alkenes because of the greater nucleophilicity of this reagent; a reaction step involving co-ordination at osmium rather than subsequent C–H cleavage is probably rate-determining. Cluster 1 decarbonylates in daylight to give [Os3(µ-H)(µ3-Ph3PCCHO)(CO)9]3 containing the µ3-ligand co-ordinated through an alkylidene bridge and a formyl group (X-ray structure). Cluster 3 is photochemically stable but thermally decarbonylates to give [Os3(µ-H)2(µ3-C6H4PPh2CCHO)(CO)8]5(X-ray structure) by orthometallation at one Ph ring of the triphenylphosphonium group. Like its isomer 1, the decacarbonyl 2 also decarbonylates in visible light to give in this case two isomers of 3, [Os3(µ-H)(µ3-Ph3PCHCO)(CO)9]4a and 4b, which differ only in the stereochemistry at the carbon atom Ph3PCHCO. Selection of one crystal from a mixture of 4a and 4b allowed the crystal structure of isomer 4a to be determined.

Formation of Fe3(NCMe)(CO)9 during the reaction of Fe3(μ3-CMe)(CO)10X clusters with alkynes (X = no) or diazoalkanes (X = H). First examples of ethylidyne-nitrogen coupling to acetonitrile

Abstract Reaction of the clusters Fe3(μ3-CCH3)(CO)10X with alkynes (X = NO) or diazoalkanes (X = H) lead among other products to the cluster Fe3(CH3CN)(CO)9 in yields varying from 1 to 18%, the acetonitrile ligand resulting from the coupling of the ethylidyne ligand with nitrogen.