1243250-51-2Relevant academic research and scientific papers
Easy kinetic resolution of some β-amino alcohols by Candida antarctica lipase B catalyzed hydrolysis in organic media
Alalla, Affef,Merabet-Khelassi, Mounia,Riant, Olivier,Aribi-Zouioueche, Louisa
, p. 1253 - 1259 (2016)
Herein, we present an easy and eco-friendly pathway to obtain some enantiomerically enriched β-amino alcohols using essentially as β-blockers. The enzymatic hydrolysis is conducted in hydrophobic organic media, assisted by sodium carbonate and CAL-B. We describe a new and effective procedure in terms of the chemo- and enantioselectivity, which allows for the formation of both enantiomers: the 2-acetamido-1-arylacetates and 2-acetamido-1-arylethanols were obtained with high ee values (up to >99%), while the selectivities reached E >200. The obtained results show a high CAL-B affinity toward the deacylation of the 2-acetamido-1-arylacetates compared to the acylation one. The structure of the 2-acetamido-1-arylacetates had a significant influence on both reactivity and selectivity of the CAL-B catalyzed deacylation. A multigram scale O-deacylation of racemic 2-acetamido-1-phenylacetate has been carried out, giving access both enantiomers with high enantiomeric purity and good isolated chemical yields.
1,2-oxazines as building blocks for stereoselective synthesis: Preparation of oxygen-substituted 1,2-oxazines, either by alcohol addition or by epoxidation, and subsequent hydrogenation leading to 1,2-amino alcohols and pyrrolidines
Zimmer, Reinhold,Buchholz, Monika,Collas, Markus,Angermann, Joerg,Homann, Kai,Reissig, Hans-Ulrich
experimental part, p. 4111 - 4121 (2010/10/02)
Stereodefined oxygen-substituted 1, 2-oxazines were prepared by three different routes. The cycloaddition of enol ethers such as 1 with a-nitrosoalkenes generated in situ gave the heterocycles 3 and 4. Acid-catalysed additions of alcohols to the 6H-1, 2-oxazines 5 led to mixtures of the adducts 6 and the substitution products 7 with moderate chemoselectivity. Epoxidation of the 6H-1, 2-oxazines 5 proceeded more efficiently and furnished the corresponding epoxides 25 and 32 in reasonable to excellent yields. It was demonstrated that the resulting oxygen-substituted 1, 2-oxazines were suitable precursors for the preparation of cyclic or acyclic primary and secondary amines in racemic or enantiopure form. Hydrogenation of the 3-phenyl-substituted 1, 2-oxazines 3 and 25a and of (6S)- and (6R)-32 preferentially furnished the 1, 2amino alcohols 15, rac-29 and (2S)- and (2R)-29. On the other hand, reduction of the 3-ethoxycarbonyl-substituted 1, 2-oxazines 4, 6d and 20 led to the formation of the N-protected proline esters 21-24 in moderate yields. It was also found that the 5-methyl-6H-1, 2-oxazine 10 was a good precursor for the propargylic ether 11, which allowed a Pauson-Khand reaction leading to the tricyclic compounds 13 and 14. Hydrogen peroxide converted 10 into a hydroperoxide intermediate, which was further transformed into the l, 2-oxazin-6-one 28b. Overall, the results demonstrate the remarkable potential of suitably substituted 1, 2-oxazine derivatives for the stereoselective synthesis of amines.
