Reaction of trialkyl orthoformates with the aluminium derivatives of some α-unsaturated bromides. Preparation of β-unsaturated acetals

✍ Scribed by Picotin, Gérard ;Miginiac, Philippe

• Publisher: Wiley (John Wiley & Sons)
• Year: 1986
• Tongue: English
• Weight: 297 KB
• Volume: 119
• Category: Article
• ISSN: 0009-2940
• DOI: 10.1002/cber.19861190524

✦ Synopsis

Reaktion von Trialkylorthoformaten mit den Aluminium-Derivaten einiger a-ungesiittigter Bromide. Darstellung von jl-ungesiittigten Acetalen Die Aluminium-Derivate 2,4 und 7 a-ungesattigter Bromide, dargestellt in Ether, sind sehr reaktionsfiihig gegeniiber Trialkylorthoformaten. Mit Hilfe dieser Reaktion, durchgefiihrt bei -8O"C, konnen auf einfache Weise P-ungesattigte Acetale 3,5 bzw. 8 dargestellt werden.

It is well known that the reactivity of Grignard reagents towards trialkyl orthoformates is rather low'-'): for the formation of an acetal to be successful it is necessary either to reflux the reaction mixture in ether for several hours or to distill the ether from the reaction solution and to cautiously heat the residue until a highly exothermic reaction begins.

It has been shown that by using the mixed orthoformate CsHSO -CH(OC2H5), (1) an acetal could be easily prepared from a Grignard reagent at room temperature*-I".

RMgX + C B H ~O -C H ( O C ~H ~) ~

. -c R-CH(OCzHs)z