Stereoselective synthesis of (1R)- and (1R,2S)-1-aryl-2-alkylamino alcohols from (R)-cyanohydrins

Autor:	Franz Effenberger, Jürgen Jäger, Beate Gutterer
Rok vydání:	1997
Předmět:	Inorganic Chemistry chemistry.chemical_compound Primary (chemistry) Chemistry Aryl Organic Chemistry Organic chemistry Chelation Stereoselectivity Physical and Theoretical Chemistry Alkylation Racemization Catalysis
Zdroj:	Tetrahedron: Asymmetry. 8:459-467
ISSN:	0957-4166
DOI:	10.1016/s0957-4166(96)00527-7
Popis:	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-alkylimino compounds in comparison to the N-unsubstituted imines is explained by a weaker chelating effect.
Databáze:	OpenAIRE
Externí odkaz:	https://explore.openaire.eu/search/publication?articleId=doi_________::6dec3e0be2f40d62346e3710931e5ef4 https://doi.org/10.1016/s0957-4166(96)00527-7 Zobrazit plný text záznamu Full Text from ScienceDirect