Arlette Solladié-Cavallo

Reduction of β-ketosulfoxides : a highly efficient asymmetric synthesis of both enantiomers of methyl carbinols from the corresponding esters

Abstract It is shown that reductions of β-ketosulfoxides of identical chirality (R) at sulfur, lead to reduction products of opposite stereochemistry according to the reducing agent used. The high enantiomeric excesses obtained (80 to 100%) provide a general route to both enantiomers of methylcarbinols from the corresponding esters.

Asymmetric induction in benchrotrene derivatives: diarylimines

Abstract A high degree of asymmetric induction can be obtained in reactions of Grignard reagents with chiral chromium tricarbonyl complexes of diarylimines.

Coordination site of Cr(CO)3 in polyaromatic compounds

The coordination site of Cr(CO)3 in diarylimines derived from aromatic aldehydes or ketones and aromatic amines has been studied. The results show that electron density is not a unique determining factor. It is suggested that consideration of the three ligand π levels (energy, symmetry, representativity) can account for the results.

Asymmetric palladium-assisted alkylation of olefins

Abstract Palladium-promoted alkylation of some alkenes using chiral sulfoxide-containing carbanion as nucleophiles or using optically N,N-dimethyl-α-phenylethylamine as ligand together with a non-chiral stabilized carbanion as nucleophile results in an asymetric induction of 10–40%.

Some new arene-chromium dicarbonyl chelates

Abstract The photochemical synthesis, spectroscopic properties (IR, 1H NMR, 13C NMR) X-ray structure of some novel chromium(O) dicarbonyl chelates are described.

Double asymmetric induction in benchrotrene derivatives

Abstract Attachment of a Cr(CO) 3 moiety to one of the aromatic rings in rigid diaryl ketones of very low prochirality followed by addition of a chiral and optically pure reagent leads to satisfactory asymmetric induction ~40%. Asymmetric induction is smaller in the case of acyclic systems.

Effect of the nature and position of the chiral auxiliary on stere-oselective synthesis of oxazolines.

High diastereoselectivity is obtained upon addition of ethyl isocyanoacetate 1 to chromium-complexed aldehydes 3 and 4. An X-ray analysis of one of the major diastereomers5ta confirms the model of approach generally used to predict the configuration of the major diastereomer obtained upon nucleophilic addition onto the carbonyl center of arene-chromium-tricarbonyl complexes. A comparison with the low d.e. obtained upon addition of a chiral isocyanoacetate onto uncomplexed aldehydes demonstrates the high efficiency of chiral arene-chromium-tricarbonyl complexes.RiassuntoUn’alta stereoselettività è ottenuta in seguito alla somma di isocianoacetato di etile1 alle aldeidi cromo-complesse3 e4. L’analisi ai raggi X di uno dei disatereoisomeri prevalenti5ta conferma il modello di approccio generalmente usato per prédire la configurazione del diastereisomero principale, proveniente dall’addizione nucleofila sul centro carbonilico di complessi arenecromotricarbonile. Un confronto con il basso d.e. ottenuto per somma di un isocianoacetato chirale su aldeidi non complessate dimostra 1’alta efficienza di complessi arene-cromo-tricarbonile chirali.