A Tri-benzotriazole Derivative Usable for a Carboxy Carbanion Synthon

Tris(1H-benzotriazol-1-yl)methane (1) is a three benzotriazolyl group-substituted methane derivative and it can be used as a precursor of a carboxy carbanion synthon.^1） The active methine of 1 is easily deprotonated by the action of butyl lithium to form a lithiated intermediate 2. Consequent reactions with various electrophiles produce the adducts 3. The tri-benzotriazolyl moiety of the given products 3 are converted to the corresponding carboxylic acid moiety by an acid-catalyzed hydrolysis. Therefore, the lithiated intermediate 2 is considered to be a carboxy carbanion synthon. Other carboxy carbanion synthons such as cyanide ion or lithiated orthothioesters^2） have disadvantages like toxicity and a sulfur odor. Thus, 1 is a useful precursor of a carboxy carbanion synthon because it is easy to handle.