New Method for the Synthesis of 2‐Aza‐1,3‐Butadienes
作者:Attila Sisak
DOI:10.1080/00397910600946033
日期:2006.12
Abstract 2‐Aza‐1,3‐butadienes have been synthesized from carbonyl compounds and 1,1,1,3,3,3‐hexamethyl‐disilazane in the presence of cobalt‐containing catalysts. The best yields (up to 95%) were achieved in the case of aldehydes branched in the α-position and 2-methylcyclohexanone. In the case of two α,β‐unsaturated ketones, pyridine derivatives were found as the main products.
The hexamethyldisilazane magnesium salt, a new base readily electrogenerated in an undivided cell fitted with a sacrificial magnesium anode, using a normally equilibrating medium (DME/15% vol HMPA mixture), exhibited a surprising regioselectivity leading to the less highly substituted silyl enol ethers from unsymmetrical ketones. This regioselectivity was not temperature dependent, but was strongly dependent on the nature and proportions of the solvent/cosolvent mixture. Moreover, the reaction was different in pure NMP, and exclusively afforded, from 2-pentanone, the new silylated aldol (56% yield) which resulted from the condensation of the less highly substituted enolate with the ketone.
Emde, Herbert; Goetz, Andreas; Hofmann, Karin, Liebigs Annalen der Chemie, 1981, # 9, p. 1643 - 1657
作者:Emde, Herbert、Goetz, Andreas、Hofmann, Karin、Simchen, Gerhard