3- Methylthiazolium tetrafluoroborate

Chen et al prepared [2-i3C]-labeled 3-benzyl and 3-methylthiazolium tetrafluoroborate (may be liquids in nature) and studied the reactions of benzaldehyde with thiazolium salts in Me2SO. They found that the reactions of thiazolium salts with aromatic aldehydes p>-anisaldehyde and cinnamaldehyde, in MeOH/MeONa, led to the formation of significant amormts of the corresponding dimethyl acetals, rather than to the benzoin products (Chen et al 1994). 

The reaction between JV-methylthiazolium iodide or tetrafluoroborate with l,l-bis(diphenyl-phosphino)ferrocene-> -ethene-platinum (57) leads to the formation of a ring expanded adduct (58) by formal C—S insertion <94JA5180>. A mechanism for the ring-opening process based on an initial nucleophilic attack on C-2 of the thiazolium ring is shown in Scheme 9. 

Zhou et al. have used the 3-ethyl-5-(2-hydroxyethyl)-4-methylthiazolium bromide for the microwave-assisted intramolecular Stetter reaction using imidazolium-type room temperature ionic liquids (RTILs) as solvents. The intramolecular Stetter reaction of ( )-methyl 4-(2-formylphenoxy) but-2-enoate was selected as a model to optimize the reaction conditions, using butylmethylimidazolium tetrafluoroborate [bmim]+[BF4]- as the solvent. It is known that salts of various heterocycles, including imidazolium salts, can also be used as catalysts. Therefore, the ionic liquids used as solvent is also able to function as a catalyst, even if it is less active than the usual thiazolium salts, and the yields of the desired product in that case are very poor. Subsequently, it was observed that when the quantity of thiazolium salt increased from 5 to 15 mol%, the yield improved accordingly to 96%. Under microwave irradiation, a variety of aromatic substrates undergo the intramolecular Stetter... 

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