Patent ID: 6025496
Filing Date: 2000-02-15
Classification: C07D,C07F

Abstract:
A process for the preparation of a heterocyclic carbene of the formula ##STR5## wherein R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are individually selected from the group consisting of unsubstituted or substituted alkylidene of 2 to 5 carbon atoms, unsubstituted or substituted alkylidine and alkylidyne of 2 to 5 carbon atoms, unsubstituted or substituted aryl of of 6 to 14 carbon atoms and unsubstituted or substituted aralkyl of 7 to 19 carbon atoms and R.sup.3 and R.sup.4 can be hydrogen or together with the carbon atoms to which they are attached form a fused on a group of 5 to 9 carbon atoms, the substituents being at least one member of the group consisting of halogen, --NH.sub.2, --NO.sub.2, --CN, isonitrile, --OH, .dbd.O, --COOH, --CONH.sub.2, pyridyl and azolyl, X is carbon or nitrogen with the proviso that R.sub.3 is not present when X is nitrogen comprising reacting at -75.degree. to 0.degree. C. in the absence of air and moisture an azolium salt of the formula ##STR6## wherein R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are defined as above and A is selected from the group consisting of halide, pseudohalide, borate, phosphate, carboxylate and metal complex ion with a deprotonation agent in pure liquid ammonia or pure alkylamine of 1 to 4 carbon atoms liquid at the reaction temperature or a mixture of pure ammonia and said pure alkylamine and an organic polar aprotic solvent.