3,4,-dihydro-2H-pyrans

US4845247A · kind A · utility

Assignee

• BASF SE

Inventors

• Wolfgang Spiegler · Worms, DE
• Norbert Goetz · Worms, DE
• Manfred Sauerwald · Meckenheim, DE
• Toni Dockner
• Rolf Fischer · Heidelberg, DE

Key dates

• Filing date: Jul 23, 1987
• Grant date: Jul 4, 1989
• Expiry date: Jul 23, 2007

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C07D309/28
• WIPO field: Organic fine chemistry
• WIPO sector: Chemistry

Abstract

3,4-dihydro-2H-pyrans I ##STR1## where R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are each H or C.sub.1 -C.sub.6 -alkyl and R.sup.3 is not C.sub.2 -C.sub.4 -alkyl when A is COOR.sup.5 and A is COOR.sup.5, .dbd.CHOR.sup.5, in which R.sup.5 is C.sub.1 -C.sub.4 -alkyl, or CH.sub.2 OR.sup.6, in which R.sup.6 is C.sub.1 -C.sub.4 -alkyl or is benzyl which is unsubstituted or substituted by C.sub.1 -C.sub.4 -alkyl, alkoxy or halogen, or is formyl, C.sub.2 -C.sub.4 -alkylcarbonyl or benzoyl which is unsubstituted or substituted by C.sub.1 -C.sub.4 -alkyl, alkoxy or halogen, are prepared by eliminating an alcohol from a 2-alkoxytetrahydropyran II ##STR2## where R.sup.7 is C.sub.1 -C.sub.18 -alkyl and A' is COOR.sup.5, CH(OR.sup.5).sub.2 or CH.sub.2 OR.sup.6, in which R.sup.5 and R.sup.6 have the meanings stated for I, the elimination being carried out by passing II, in the liquid or gaseous state, into a high boiling mineral oil at above the boiling point of the resulting dihydropyran I, removing I in gaseous form, replenishisng the high boiling mineral oil when it becomes enriched with byproducts, and removing the said mineral oil enriched with byproducts.