Preparation of alkyl O,O-dialkyl-.gamma.-phosphonotiglates

US4937308A · kind A · utility

Assignee

• BASF SE

Inventors

• Guenter H. Knaus · Ludwigshafen, DE
• Hansgeorg Ernst · Speyer, DE
• Marco Thyes
• Joachim Paust · Schifferstadt, DE

Key dates

• Filing date: Jun 10, 1988
• Grant date: Jun 26, 1990
• Expiry date: Jun 10, 2008

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C07F9/4015
• WIPO field: Organic fine chemistry
• WIPO sector: Chemistry

Abstract

Alkyl .gamma.-halotiglates of the general formula I ##STR1## where X is Cl or Br and R.sup.2 is alkyl of 1 to 3 carbon atoms, having a high E isomer content, are prepared by a process in which PA0 (a) the corresponding 2-methyl-but-3-enoate of the general formula II ##STR2## is reacted with chlorine or bromine in the absence of a solvent and (b) the resulting 2-methyl-3,4-dihalobutyrate of the general formula III ##STR3## is dehydrohalogenated by reaction with a solution of an alkali metal hydroxide in an alcohol R.sup.2 OH, where R.sup.2 has the stated meaning, or in a mixture of water and an alcohol R.sup.2 OH, and the products are further processed to give O,O-dialkyl-.gamma.-phosphonotiglates of the general formula IV ##STR4## where R.sup.1 is alkyl of 1 to 4 carbon atoms and R.sup.2 is alkyl of 1 to 3 carbon atoms, preferably ethyl, by reaction with a trialkyl phosphite and thermal isomerization. The process gives C.sub.5 building blocks which are extremely interesting for polyene chemistry, the said building blocks being obtained in good yields and essentially in the form of the required E isomers.