ES268395A1 - Process for the production of new derivatives of hydrogenated pyridones - Google Patents

Abstract

The invention comprises compounds of the formula <FORM:0920140/IV(a)/1> (wherein R1 and R2 are hydrocarbon radicals or together represent an alkylene radical of 4 to 7 carbon atoms, R3 is an alkyl radical of at most 5 carbon atoms, an aryl or an aralkyl radical and R4 is an alkyl radical of at most 4 carbon atoms or an aryl radical) and their preparation by condensing, in presence of a mineral acid, an isoxazole of the formula <FORM:0920140/IV(a)/2> with a compound which yields a carbonium ion \sJC(R1.R2)CH2COR3. Such compounds may be, for example, unsaturated ketones C(R1.R2)=CHCOR3, hydroxy ketones HO.C (R1R2)CH2COR3 or haloketones Hal.C(R1.R2) CH2COR3 or ketals thereof or \sJC(R1R2) CH2CCR5 (R5 being hydrogen or an alkyl radical containing one less carbon atoms than the number of carbon atoms in R3 when this is alkyl, suitable compounds being the alcohols HO.C(R1.R2)CH2CCR5) prepared from ketones R1.R2CO and suitably substituted propargyl magnesium halides. Reaction with the unsaturated ketones may proceed through the intermediate <FORM:0920140/IV(a)/3> which compound, or an acetal, enol ether or enol ester thereof may then be cyclized to the required compound by treatment with an acid or basic condensing agent or it may proceed through the intermediate <FORM:0920140/IV(a)/4> or through the 3,4-dihydro-derivatives of the required products, which may then be obtained by dehydration or dehydrogenation. Reaction with the unsaturated alcohols proceeds direct if a mercury salt is also present, or, if this is absent, intermediates of the formula <FORM:0920140/IV(a)/5> are obtained, and then converted into the required products by treatment with sulphuric acid containing a mercury salt. Detailed examples are provided.