3082-66-4Relevant academic research and scientific papers
Alkylation of a Chiral Hydrazone by Means of Asymmetric Addition of Grignard Reagents to the Carbon-Nitrogen Double Bond
Takahashi, Hiroshi,Suzuki, Yuji
, p. 4295 - 4299 (2007/10/02)
A chiral hydrazone, (E)-(S)-N'-benzylidene-N,3-dimethyl-2-hydrazinobutanol (6), was synthesized from (S)-valinol.Compound was reacted with Grignard reagents to give optically pure (2S,1'S)-N,3-dimethyl-N'-1'-phenylalkyl-2-hydrazinobutanols (7a and 7b).However, N'-2-aryl-1'-phenylethyl-N,3-dimethyl-2-hydrazinobutanols (7c and 7d) were each obtained as a mixture of two diastereomers.Nitrogen-nitrogen bonds of 7a and 7b were cleaved by hydrogenolysis to give (S)-1-phenylalkyamines (8a and 8b), and their absolute configurations and optical purities were confirmed.These reactions were assumed to proceed via the chelated six-membered ring intermediates.Keywords -- absolute configuration; asymmetric reaction; chelated intermediate; chiral hydrazine; chiral hydrazone; conformation control; l-ephedrine; Grignard reaction; stereoselectivity; (S)-valinol
