Patent ID: 6559343
Filing Date: 2003-05-06
Classification: C07C,C07F

Abstract:
A process for the preparation of 2,2,4,4-tetrasubstituted 1,3,5-cyclohexanetriones of the formula I in whichR1, R2 are C1-C6-alkyl or C3-C6-cycloalkyl, where these two radicals are unsubstituted or partially or completely halogenated and/or substituted by the following radicals: C1-C4-alkoxy, C1-C4-alkylthio or di(C1-C4-alkyl)amino; C1-C6-alkoxy, C2-C6-alkenyl or C2-C6-alkynyl; aryl, aryloxy or heterocyclyl, which has up to three heteroatoms from the group consisting of O, S and N, where the aryl, the aryloxy and the heterocyclyl radical are unsubstituted or partially or completely halogenated and/or substituted by the following radicals: C1-C4-alkyl, C1-C4-haloalkyl, C1-C4-alkoxy, C1-C4-haloalkoxy or C1-C4-alkoxycarbonyl; or two radicals R1 and R2, which are bonded to the same carbon, together form a â€”(CH2)2-6â€” chain, which is optionally substituted by the following radicals: halogen, C1-C4-alkyl, C1-C4-haloalkyl, C1-C4-alkoxy, C1-C4-haloalkoxy or C1-C4-alkoxycarbonyl; which comprisesa) reacting a cyclobutane-1,3-dione of the formula II whereR1 and R2 have the abovementioned meanings, with an O or N nucleophile, optionally in the presence of a base, and a silylating reagent to give the silyl enol ether of the formula III whereR3 is C1-C8-alkoxy, amino, C1-C6-alkylamino or di(C1-C6-alkyl)amino; R4 is C1-C6-alkyl or phenyl; R1 and R2 have the abovementioned meanings; b) converting the compound III by acetylation, optionally in the presence of a Lewis acid, into the tricarbonyl compound of the formula IV, whereR1 to R3 have the abovementioned meanings; c) cyclizing the compound IV in the presence of a base to give the 2,2,4,4-tetrasubstituted cyclohexanetrione of the formula I.