37589-40-5Relevant articles and documents
Highly diastereoselective catalytic Meerwein-Ponndorf-Verley reductions
Yin, Jingjun,Huffman, Mark A.,Conrad, Karen M.,Armstrong III, Joseph D.
, p. 840 - 843 (2007/10/03)
Very practical synthesis of ephedrine analogues in high yields and enantiopurity was realized by a highly diastereoselective Meerwein-Ponndorf- Verley (MPV) reduction of protected α-amino aromatic ketones using catalytic aluminum isopropoxide. The high anti selectivity resulted from the chelation of the nitrogen anion to the aluminum. In contrast, high syn selectivity was obtained with α-alkoxy ketones and other compounds via Felkin-Ahn control.
Stereoselective synthesis of (1R)- and (1R,2S)-1-aryl-2-alkylamino alcohols from (R)-cyanohydrins
Effenberger, Franz,Gutterer, Beate,Jaeger, Juergen
, p. 459 - 467 (2007/10/03)
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.
