96228-13-6Relevant academic research and scientific papers
Stereoselective synthesis of (1R)- and (1R,2S)-1-aryl-2-alkylamino alcohols from (R)-cyanohydrins
Effenberger, Franz,Gutterer, Beate,Jaeger, Juergen
, p. 459 - 467 (1997)
Hydrogenation of (R)-cyanohydrins (R)-1 with LiAlH4 occurs without racemization to give the (R)-2-amino alcohols (R)-3. (1R,2S)-2-Amino alcohols (1R,2S)-4 are obtained with high diastereoselectivity by addition of methyl Grignard to O-silyl protected cyanohydrins (R)-2 and subsequent hydrogenation with NaBH4. The N-alkylated 2-amino alcohols (R)-8 and (1R,2S)-9 can be prepared either by reductive alkylation of the corresponding 2-amino alcohols (R)-3 and (1R,2S)-4, respectively, or by a transimination reaction of the Grignard addition products with primary amines and subsequent hydrogenation with NaBH4. The lower diastereoselectivity of hydrogenation in case of the N-alkylmino compounds in comparison to the N-unsubstituted imines is explained by a weaker chelating effect.
Carbon dioxide as a carbonylating agent in the synthesis of 2-oxazolidinones, 2-oxazinones, and cyclic ureas: Scope and limitations
Paz, Jairo,Perez-Balado, Carlos,Iglesias, Beatriz,Munoz, Luis
experimental part, p. 3037 - 3046 (2010/07/15)
Carbon dioxide can be used as a convenient carbonylating agent in the synthesis of 2-oxazolidinones, 2-oxazinones, and cyclic ureas. The transient carbamate anion generated by treating a primary or secondary amine group in basic media can be activated with phosphorylating agents such as Diphenylphosphoryl azide (DPPA) and Diphenyl chlorophosphate (DPPCl) but also with other types of electrophiles such as SOCl2, TsCl, or AcCl. The intramolecular trapping of the activated carbamate by a hydroxyl group leads to the formation of 2-oxazolidinones or 2-oxazinones in good to excellent yields. This methodology was successfully applied to the synthesis of cyclic ureas up to 7-membered rings from the corresponding diamines.
β-Amino alcohols derived from (1R,2S)-norephedrine and (1S,2S)-pseudonorephedrine as catalysts in the asymmetric addition of diethylzinc to aldehydes
Parrott II, Raleigh W.,Hitchcock, Shawn R.
, p. 19 - 26 (2008/09/16)
A family of N-alkylnorephedrine and N-alkylpseudonorephedrine derived ligands were prepared and applied in the asymmetric alkylation of benzaldehyde using diethylzinc. The absolute configuration of the addition product was directed primarily by the benzylic position of the Ephedra alkaloid, while the magnitude of the enantiomeric ratio was heavily influenced by the nitrogen substituent. However, sterically demanding substituents at the nitrogen position caused the enantioselectivity to be the same for the two diastereomeric systems. Among the ligands that were prepared, it was determined that the N-cyclooctylpseudonorephedrine derivative 7b yielded the highest enantiomeric ratios (87.5:12.5 to 91.0:9.0) when applied in the catalytic asymmetric addition of diethylzinc to aldehydes.
Intramolecular Chiral Relay at Stereogenic Nitrogen. Synthesis and Application of A New Chiral Auxiliary Derived from (1R,2S)-Norephedrine and Acetone
Hitchcock, Shawn R.,Casper, David M.,Vaughn, Jeremy F.,Finefield, Jennifer M.,Ferrence, Gregory M.,Esken, Joel M.
, p. 714 - 718 (2007/10/03)
(1R,2S)-Norephedrine has been employed in the synthesis of a novel 3,4,5,6-tetrahydro-2H-1,3,4-oxadiazin-2-one via reductive alkylation with acetone, N-nitrosation, reduction, and cyclization. The oxadiazinone was treated with either propionyl chloride or
Mapping the stereochemical course of carbonyl phosphonylation via chiral phosphorodiamidites
Cain, Mark J.,Baird, Christopher A.,Kee, Terence P.
, p. 8671 - 8674 (2007/10/02)
The asymmetric phosphonylation of aldehydes via chiral phosphorodiamidites has been examined as a function of the steric profile of the chiral auxiliary employed. Comparison of N-Me and N-(i)Pr-(1R,2S)-ephedrine auxiliaries reveals that the latter results in a consistently stronger preference for (S(p),S(C)) product stereochemistry than the former.
