Synthesis of (-)-Indolizidine 167B based on domino hydroformylation/cyclization reactions

The synthesis of (-)-Indolizidine 167B has been achieved from optically active (R)-3-(pyrrol-1-yl)hex-1-ene. The key step is a highly regioselective hydroformylation reaction and a one-pot intramolecular cyclization providing a general approach to the indolizine nucleus

Rhodium-catalyzed hydroformylation of 4-vinylpyridine: 4-ethylpyridine formation via an unusual cleavage of the Rh?C bond by the enolic form of the oxo product.

The hydroformylation of 4-vinylpyridine (4VP) with rhodium catalyst Rh4(CO)12 modified with phosphine ligands (PMe2Ph) is not completely chemoselective to the branched aldehyde 2-(4-pyridyl)propanal (4α), the corresponding hydrogenation product 4-ethylp

(5R)-5-alkyl-5,6-dihydroindolizines via stereospecific domino hydroformylation/cyclodehydration of (3R)-3-(pyrrol-1-yl)alk-1-enes

(5R)-5-Alkyl-5,6-dihydroindolizines 3a-c having the same high enantiomeric excess (>92%) as the corresponding starting olefins (3R)-3-(pyrrol-1-yl)alk-1-enes 1a-c were obtained via a highly regioselective and stereospecific domino hydroformylation/cyclodehydration reaction sequence. The reasons for this configurational stability were also analyzed in the light of the general accepted rhodium catalyzed hydroformylation mechanism

[PtCl3(C2H4)]-[(S,S)-(PhMeCH)2NH2]+: A new and versatile ionic organometallic chiral derivatizing agent for the determination of the enantiomeric composition of chiral unsaturated compounds by 195Pt NMR spectroscopy

The ionic complex [PtCl3(C2H4)]-[(S,S)-(PhMeCH)2NH2]+ containing a chiral secondary amine is a new and versatile chiral derivatizing agent (CDA) for the determination of the enantiomeric composition of several unsaturated compounds including simple olefins: the diastereoisomeric mixtures arising from the exchange of ethylene by the unsaturated analytes are easily detected by 195Pt NMR spectroscopy

Use of cis-dichloro[(S)-a-methylbenzylamine](ethylene)Pt(II) as a chiral derivatizing agent for the determination by 195Pt-NMR of the enantiomeric composition of unsaturated ethers or alcohols having a quaternary chiral carbon atom

cis-Dichloro[(S)-a-methylbenzylamine](ethylene)platinum(II) is an efficient chiral derivatizing agent for the determination, by 195Pt-NMR spectroscopy, of the enantiomeric composition of unsaturated ethers and alcohols having a quaternary chiral carbon ato

Influence of the Reaction Temperature on the Regioselectivity in the Rhodium-Catalyzed Hydroformylation of Vinylpyrroles

The influence of the temperature on the regioselectivity in the hydroformylation of the vinylpyrrole isomers and of the corresponding N-tosylated substrates has been investigated in the range 20-100°C, in the presence of Rh4(CO)I2. At all the temperatures the branched aldehyde was prevailing with respect to the linear isomer for all the substrates (a-regioselectivity). With increasing temperature, an increase of the linear aldehyde was observed to a different extent in dependence on the substrate nature. 2H NMR investigation of the crude reaction mixture recovered from deuterioformylation of 3-vinylpyrrole at partial substrate conversion points out that the observed depression of the c~-regioselectivity with increasing temperature must be connected to a /3-hydride elimination process occurring for the branched alkyl-rhodium intermediates but not for the linear ones

Chiral N-Allylpyrroles as Versatile Substrates Under Rhodium-Catalyzed Hydroformylation: Good Regio- and Diastereo-Selectivity at Room Temperature and High Pressure

The chiral (S)-3-alkyl-3-(pyrrol-1-yl)prop-1-enes (1a-c) were hydroformylated at 20 °C and high pressure (100 atm) giving the branched aldehydes 2-methyl-3-(pyrrol-1-yl)alkanales (2+2’) with a good region-selectivity and a high diastereomeric excess (2/2’ up to 90:10). The absolute configuration of the diastereomers was assigned via NMR measurements, 2S,3S being the predominant one