An effective one-pot conversion of acid chlorides to aldehydes and ketones

Aldehydes and ketones were synthesized from their respective acid chlorides via a one-pot protocol. Morpholine amide intermediates that were readily prepared by the aminolysis of various acid chlorides with diisobutyl(morpholino)aluminum smoothly reacted with the reducing agent LDBMA and the organolithium reagents under mild reaction conditions (0 °C), giving almost excellent product yields of up to 95%.     

Synthesis of Aminocholesterol Derivatives with Antibiotic Properties

We report here a new family of antibiotic with fungicidal and antibacterial activity. The syntheses of five 7-amino and 7-aminoalkylcholesterol derivatives are described.     

Molecular motility and affinity of expanded carbon dioxide + ketone systems analyzed by molecular dynamics simulations

We perform a molecular dynamics simulation for CO₂ + ketone mixtures to study the molecular motility and elucidate how CO₂ molecules are dissolved in a mixture. The self-diffusion coefficients increase with increasing CO₂ mole fraction (xCO₂)$(x_{\text{C}{\text{O}}_2})$ and decreased with increasing molecular weight. These results mean that the mobility of molecules depends on the molecular size. To study molecular aggregation around CO₂ molecules, radial distribution functions (RDFs) and the distance from neighboring molecules to CO₂ molecules were calculated. The RDFs indicate that the CO₂ molecule exists near the carbonyl oxygen atom. Because of the distance of the neighboring molecule from the CO₂ molecule, the CO₂ molecule is less likely to exist around a branched alkyl ketone than a normal alkyl ketone.     

Highly enantioselective reduction of ketones by chiral diol-modified lithium aluminum hydride reagents

Some readily available chiral diols from indene and d-mannitol were investigated as chiral modifiers in lithium aluminum hydride reduction of ketones, and it was discovered that further modification of these reducing reagents by a simple a-amino alcohol resulted in a remarkable increase in optical yield. Among the investigated chiral modifiers, chiral diol 1 gave the highest enantioselectivities.     

The first synthesis and X-ray structures of polyfluorinated 1,2-, 2,3- and 2,4a-dihydro-1,3-diazafluorenes

Acetic acid-catalyzed condensation of 2-amino-3-(1-imino-2,2,2-trifluoroethyl)-1,1,4,5,6,7-hexafluoroindene (1b) with acetone and cyclopentanone gives 5,6,7,8,9,9-hexafluoro-2,2-dimethyl-4-trifluoromethyl-2,3-dihydro-1,3-diazafluorene (2a) and 5,6,7,8,9,9-hexafluoro-4-trifluoromethyl-2,3-dihydro-1,3-diazafluorene-2-spiro-1′-cyclopentane (3a) together with small amounts of 5,6,7,8,9,9-hexafluoro-2,2-dimethyl-4-trifluoromethyl-1,2-dihydro-1,3-diazafluorene (2b) and 5,6,7,8,9,9-hexafluoro-4-trifluoromethyl-1,2-dihydro-1,3-diazafluorene-2-spiro-1′-cyclopentane (3b), respectively. When acted upon by (CH₃)₂SO₄ compounds 2, 3 were converted into corresponding fluorine-containing 1-methyl-1,2-dihydro-1,3-diazafluorenes 6, 7. 4a-Chloro-5,6,7,8,9,9-hexafluoro-2,2-dimethyl-4-trifluoromethyl-2,4a-dihydro-1,3-diazafluorene (8) has been synthesized by the interaction of compound 2 with SOCl₂. Solution of compound 2 as well as 8 in CF₃SO₃H-CD₂Cl₂ generated 5,6,7,8,9,9-hexafluoro-2,2-dimethyl-4-trifluoromethyl-1,2,3,4-tetrahydro-1,3-diazafluorene-4-yl cation (2c). The structures of compounds 2, 3, 6-8 have been determined by single crystal X-ray diffraction.     

Catalytic ketone olefination with methyltrioxorhenium

Methyltrioxorhenium (MTO) catalyses the olefination of ketones with ethyl diazoacetate in the presence of triphenylphosphane. Unactivated ketones require the addition of 0.5 equiv of benzoic acid to achieve good yields, while trifluoromethyl ketones require no co-catalyst. The optimised system allows the olefination of aromatic, aliphatic, unsaturated, cyclic and trifluoromethyl ketones.     

Rapid identification of enantioselective ketone reductions using targeted microbial libraries

A collection of about 300 microbes was surveyed for the ability to generate chiral secondary alcohols by enantioselective reduction of a series of alkyl aryl ketones. Microbial cultures demonstrating utility in reducing model ketones were arrayed in multi-well plates and used to rapidly identify specific organisms capable of producing chiral alcohols used as intermediates in the synthesis of several drug candidates. Approximately 60 cultures were shown to selectively reduce various ketones providing both the R and S enantiomers of the corresponding alcohols in 92-99% ee with yields up to 95% at 1-4 g/L. An alternative approach to chiral alcohols based on selective microbial oxidation of racemic alcohols is also reported. This study provides a useful reference for generating chiral alcohols by selective microbial bioconversion.