THEORETICAL-STUDY OF A TERMOLECULAR MECHANISM FOR THE REACTION OF (TRIMETHYLSILYL)THIAZOLE WITH CARBONYL-COMPOUNDS

The mechanism of the addition of 2-silylthiazole to formaldehyde has b een studied by ab initio calculations at the MP2/6-31+G//6-31G* level . The reaction is predicted to occur by the concerted formation of an N-[(silyloxy)methyl]thiazolium-2-ylide intermediate followed by nucleo philic addition of the intermediate to another formaldehyde molecule. Loss of the first formaldehyde gives the addition product. An alternat ive mechanism involving 1,2-migration of the ylide to form 2-[(silylox y)methyl]thiazole is prevented because of the high activation energy o f the 1,2-shift. A third mechanistic alternative involving the formati on of an N-silylthiazolium-2-ylide through 1,2-silyl migration is also discounted due to a high activation energy.