ABSTRACT
In this study, the novel bifunctional homochiral thiourea-L-prolinamides 1-4, tertiary amino-L-prolinamide 5, and bis-L-prolinamides 6 and 7 were prepared from enantiomerically pure (11R,12R)-11,12-diamino-9,10-dihydro-9,10-ethanoanthracene 8 and (11S,12S)-11,12-diamino-9,10-dihydro-9,10-ethanoanthracene ent-8. Highly enantioselective and diastereoselective aldolic intermolecular reactions (up to 95% enantiomeric excess, 93:7 anti/syn) between aliphatic ketones (20 equiv) and a range of aromatic aldehydes (1 equiv) were successfully carried out in the presence of water (10 equiv) and monochloroacetic acid (10 mol%), solvent-free conditions, at room temperature over 24 h using organocatalysts 1-7 (5 mol%). Stereoselective induction using density functional theory-based methods was consistent with the experimental data.
Subject(s)
Aldehydes/chemistry , Proline/analogs & derivatives , Acetone/chemistry , Catalysis , Chemistry Techniques, Synthetic , Density Functional Theory , Ketones/chemistry , Molecular Structure , Proline/chemical synthesis , Proline/chemistry , Solvents , Stereoisomerism , Thiourea/chemistryABSTRACT
The ability of α-diazo-ß-ketoesters bearing a substituent on the benzylic position to undergo aromatic C-H insertion is described. Good to excellent yields of the aromatic C-H insertion products were observed with Rh(2)(tpa)(4) or Rh(2)(esp)(2) catalysts. This is an attractive strategy to prepare tetralins carrying a methyl group on the benzylic position, a structural motif found in several types of natural products.
Subject(s)
Azo Compounds/chemistry , Carbon/chemistry , Carboxylic Acids/chemistry , Esters/chemistry , Hydrogen/chemistry , Rhodium/chemistry , Catalysis , Molecular StructureABSTRACT
Addition of organocuprates, generated in situ using an excess of a 1:2 mixture of CuI·DMS and Grignard reagent, to N-enoyl oxazolidinethiones in the presence of excess TMSI gave preferentially the anti diastereomer where the addition took place when the conformation of the substrate was syn-s-cis. The reaction was investigated with indene-based and three different phenyl glycine derived oxazolidinethiones.