Acylation, formylation and alkylation

Heating 2-phenyl-4-benzoyl-l,3,4-thiadiazolium chloride (150) at 200°C causes the benzoyl group to move to the 2-position as in (151) (68AHC(9)165), probably via deprotonation. 

4-Aminotriazole is carboxylated at the 5-position by heating with aqueous sodium bicarbonate in a Kolbe-type reaction (71JCS(C)150l). 2-Thiazolinones undergo the Gattermann and Reimer-Tiemann reactions at the 4-position, and 3- and 4-pyrazolinone anions on alkylation give 4-alkyl as well as O-and A-alkyl derivatives. 

Treatment of pyrazole with 1-bromoadamantane affords either 4-(l-adamantyl)pyrazole (94TL183, 94H(37)1623) or 3(5)-(l-adamantyl)pyrazole (94CL2079) depending on the conditions (heating in a sealed tube or heating in a microwave oven). (Other cases of C-alkylation of azoles are in Section 3.4.1.3.10). 

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