The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Nov. 10, 1992
Filed:
Jan. 05, 1989
Nicolaas L Broekhof, Naarden, NL;
Jogchum J Hofma, Amersfoort, NL;
Naarden International, N.V., Naarden, NL;
Abstract
The invention provides a process for the preparation of 5,6-dihydro-2H-pyran derivatives, wherein an aldehyde of formula I: ##STR1## wherein R.sub.1 represents an alkyl, cycloalkyl, aralkyl, alkaryl or aryl group having at most 15 carbon atoms and a diene of formula II: ##STR2## wherein R.sub.2 and R.sub.3 represents a hydrogen atom or an alkyl group having 1-6 carbon atoms are reacted in a Diels-Alder-type reaction under the influence of an inorganic Lewis acid catalyst, producing a compound of formula III wherein R.sub.1 -R.sub.3 have the meaning given above. ##STR3## Preferably R.sub.1 represents a 1-6 carbon atom alkyl group, a phenyl group or an o-, m- or p-tolyl group. Isoprene or 2-methyl-1,3-pentadiene is preferably used as the diene. The preferred catalyst is AlCl.sub.3 or SnCl.sub.4 and an organic nitro compound may be used as the co-catalyst.