Antonio Saba

CHIRAL SULFOXIDES AND SULFIDES TETHERED TO PYRIDINES AS LIGANDS FOR ENANTIOSELECTIVE CATALYSIS : PALLADIUM CATALYZED ALLYLIC SUBSTITUTION AND ADDITION OF DIETHYLZINC TO BENZALDEHYDE

Abstract Chiral 2-(1- p -tolylsulfinyl)alkylpyridines and the corresponding sulfide-pyridines were prepared and assessed in the enantioselective palladium catalyzed allylic substitution of 1,3-diphenylprop-2-enyl acetate with dimethylmalonate and addition of diethylzinc to benzaldehyde.

Enantioselective palladium catalyzed allylic substitution with 2,2′-bipyridine ligands

Abstract A number of chiral C 1 -symmetric 2,2′-bypyridines were prepared and assessed in the enantioselective palladium catalyzed allylic substitution of 1,3-diphenylprop-2-enyl acetate with dimethylmalonate. Enantioselectivity up to 89% was obtained.

Enantiomerically pure pyridine and 2,2′-bipyridine thioethers: new N–S chiral ligands for asymmetric catalysis. Palladium-catalyzed allylic alkylation

Abstract Diastereomeric pure pyridine and 2,2′-bipyridine thioethers, derived from (+)-camphor, were prepared and assessed in the enantioselective palladium-catalyzed allylic substitution of 1,3-diphenylprop-2-enyl acetate with dimethyl malonate. Enantioselectivities of up to 76% were obtained.

Optically active aldehydes via hydroformylation of 1,3-dienes with chiral diphosphinerhodium complexes

Abstract Optically active aldehydes have been obtained by hydroformylation of simple aliphatic conjugated dienes under standard oxo conditions (90 atm (CO/H 2  1/1) and 95°C), using HRh(CO)(PPh 3 ) 3 /()DIOP as catalyst. The highest optical yield (32%) was achieved in the preparation of 3-methylpentanal from isoprene.

STERIC EFFECTS OF THE LIGAND IN THE ENANTIOSELECTIVE PALLADIUM-CATALYZED ALLYLIC ALKYLATION USING CHIRAL OXAZOLINYLPYRIDINES

Eight new chiral oxazolinylpyridines were prepared and assessed in the enantioselective palladium-catalyzed allylic substitution of 1,3-diphenylprop-2-enyl acetate with dimethyl malonate. Catalytic activity and enantioselectivity were found to be highly dependent upon the steric requirement of the substituent on the pyridine ring: enantioselectivity up to 92% has been obtained.

New chiral 2,2′:6′,2″-terpyridines as ligands for asymmetric catalysis: cyclopropanation and hydrosilylation reactions

Abstract A number of new chiral 2,2′:6′,2″-terpyridines were prepared and the corresponding rhodium and ruthenium complexes were assessed as chiral catalysts for the enantioselective hydrosilylation of acetophenone with diphenylsilane and for the cyclopropanation of styrene with ethyl diazoacetate. Enantioselectivities up to 59% in the cyclopropanation and up to 13% in the hydrosilylation were obtained.

Chiral 2,2′-bipyridines, 5,6-dihydro-1,10-phenanthrolines and 1,10-phenanthrolines as ligands for enantioselective palladium catalyzed allylic substitution

Abstract A number of chiral 5,6-dihydro-1,10-phenanthrolines, 5,6-dihydrobenzo[b]-1,10-phenanthrolines and 5,6,7,8-tetrahydro-2-quinolinylquinolines derived from (−)-pinocarvone were prepared and assessed in the enantioselective palladium catalyzed allylic alkylation of 1,3-diphenylprop-2-enyl acetate with dimethylmalonate. The introduction of a benzo-fused substituent on the pyridine ring not containing the chiral backbone resulted in the drastic reduction of the stereoselectivity of the reaction. Enantioselectivities up to 81% were obtained.

Chiral oxazolinylpyridines as ligands for enantioselective palladium catalysed allylic substitution

Chiral oxazolinylpyridines were prepared and assessed in the enantioselective palladium catalysed allylic substitution of 1,3-diphenylprop-2-enyl acetate with dimethyl malonate. Enantioselectivity up to 91% was obtained.

Chiral 8-amino substituted 2-phenyl-5,6,7,8-tetrahydro-6,6-dimethylmethanoquinolines as chiral ligands for enantioselective catalysis: Palladium catalysed allylic substitution and addition of diethylzinc to benzaldehyde

Abstract Diastereomerically pure 8-amino substituted (5S,7S)-2-phenyl-5,6,7,8-tetrahydro-6,6-dimethylmethanoquinolines were prepared and assessed in the enantioselective palladium catalysed allylic substitution of 1,3-diphenylprop-2-enyl acetate with dimethyl malonate and addition of diethylzinc to benzaldehyde. Enantioselectivities up to 68% were obtained.

Chiral 2-(2-diphenylphosphinophenyl)-5,6,7,8-tetrahydroquinolines: new P–N ligands for asymmetric catalysis

Abstract New chiral phosphorus–nitrogen ligands, specifically, 2-(2-diphenylphosphinophenyl)-5,6,7,8-tetrahydroquinolines were prepared and assessed in the enantioselective palladium catalyzed allylic substitution of 1,3-diphenylprop-2-enyl acetate with dimethyl malonate. Enantioselectivity up to 71% was obtained.