78889-11-9Relevant academic research and scientific papers
Erythro-Directive Reduction of α-Substituted Alkanones by Means of Hydrosilanes in Acidic Media
Fujita, Makoto,Hiyama, Tamejiro
, p. 5415 - 5421 (2007/10/02)
Hydrosilane reduced α-oxy and α-amino ketones and β-keto acid derivatives in trifluoroacetic acid to afford the corresponding erythro alcohols with high diastereoselectivity.The reaction proceeded without racemization at the carbon α to the carbonyl group.The erythro-directive reduction was explained in terms of the proton-bridged Cram cyclic model and successfully applied to the synthesis of physiologically important amino alcohols such as l-ephedrine, l-methoxamine, and erythro-2-methyl-3-piperidino-1-phenylpropanol.
Fluoride Ion Catalyzed Reduction of Aldehydes and Ketones with Hydrosilanes. Synthetic and Mechanistic Aspects and an Application to the Threo-Directed Reduction of α-Substituted Alkanones
Fujita, Makoto,Hiyama, Tamejiro
, p. 5405 - 5415 (2007/10/02)
Reduction of aldehydes and ketones with hydrosilanes proceeded in the presence of a catalytic amount of tetrabutylammonium fluoride or tris(diethylamino)sulfonium difluorotrimethylsilicate in aprotic polar solvents under mild conditions.A significant isotope effect (kH/kD = 1.50) was observed in competitive reduction of acetophenone with HSiMe2Ph and DSiMe2Ph.The reaction was of first order in the concentration of an aprotic polar solvent HMPA.Reduction of 2-methylcyclohexanone gave cis-2-methylcyclohexanol with selectivities up to 95percent.The kinetic and stereochemical results suggest that a hexavalent fluorosilicate - is involved. α-Alkoxy (acyloxy or dimethylamino) ketones were transformed to threo alcohols in high diastereoselectivities.The reduction was also applied to α-methyl-β-keto amides, RCOCH(MeCONR)2, to afford the corresponding threo alcohols in >98percent selectivity.The threo selectivity is explained in terms of the Felkin-Anh model in which interaction of carbonyl oxygen with a countercation is ideally suppressed.The threo-directed reduction was applied to (R)-1-phenyl-4-(2-tetrahydropyranyloxy)-1-penten-3-one and N-(2-benzoylpropanoyl)piperidine.The resulting threo alcohols were respectively converted into (2R,3S)-2,3-(cyclohexylidenedioxy)butanal, a key intermediate of daunosamine synthesis, and into a pharmacologically useful compound threo-N-(3-hydroxy-2-methyl-3-phenylpropyl)piperidine.
N-substituted alpha-aminoalkylacrylophenones and some related compounds: a new class of spermicidal agents.
Gupta,Nautiyal,Jhingran,Kamboj,Setty,Anand
, p. 303 - 307 (2007/10/02)
The results of a screening program to test the spermicidal effectiveness of several compounds is presented. The program was initiated after N-substituted 3-aminoacrylophenones were found to have unexpected spermicidal activity. The compounds had been synthesized as possible antiinflammatory agents. This result prompted the synthesis and screening of N-substituted alpha-aminomethylacrylophenones, alpha-(2-aminomethyl)acrylophenones and 3-N-substituted-2-methyleneindan-1-ones. The starting materials, substituted acetophenones, for the synthesis of N-substituted alpha-aminomethylacrylophenones were either commercial products or obtained by standard methods. N-substituted amino-butyrophenone was reacted with paraformaldehyde to yield the alpha-(2 aminoethyl)acrylophenones. A series of reactions was undertaken to synthesize 2-methyleneindan-1-ones. The preparation of each is detailed and molecular formulas are provided. Spermicidal activity was assessed by dissolving the compound in physiological saline at different concentrations. 2 drops of rat sperm suspension or human semen were placed on a slide, followed by 2 drops of a compound solution. Control slides of physiological saline were prepared. The contents were mixed for approximately 5 seconds and examined under a phase contrast microscope. The results were considered positive if 100% of the spermatozoa became immotile instantaneously. Several of the compounds showed marked spermicidal activity.
