Method for preparing optically active 5-methyl-2-(1-methyl-butyl)-5-propyl-1,3-dioxan

US6297390A · kind A · utility

Assignee

• Cognis Deutschland GmbH · DE

Inventors

• Thomas Markert · Monheim, DE
• Dirk Merkel · Solingen, DE
• Hans-Josef Altenbach · Wuppertal, DE

Key dates

• Filing date: Apr 3, 2000
• Grant date: Oct 2, 2001
• Expiry date: Apr 3, 2020

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C07D319/06
• WIPO field: Organic fine chemistry
• WIPO sector: Chemistry

Abstract

The present invention relates to a method for preparing optically active 5-methtyl-2-(1-methtyl-butyl)-5-propyl-1,3-dioxan, wherein said method comprises the following steps: converting lactic acid methylic ester into the corresponding N,N-disubstituted amid (aminolysis with piperidine and/or pyrrolidine); protecting its free OH function by a reaction with ethylvinylether in the presence of p-pyridiniumtosylate as a catalyst; submitting the N-pentamethylen- or N-tetramethylenlactamide thus obtained to a Grignard reaction in a conventional way so as to produce the corresponding .alpha., .beta.-unsaturated ketone; further separating in a conventional way (e.g. agitation with acetic acid) the protection group introduced during the second step; acetalating in a conventional way the ketone function (e.g. by reaction with 2-methyl-2-propyl-1,3-propanediol); mesylating the free OH function by reaction with methansulfonic acid chloride in pyridine; submitting the intermediate thus obtained to a reducing 1,2-transposition in the presence of trimethylammonium and diisobutylaluminum hydride while maintaining the sterochemistry; and converting by catalytic hydrogenation the dehydro compound th…