Imidazolones lithium compounds

The methyl hydrogens in 1,3,5- and 1,4,5-trimethyl tetrazoliums, as well as the proton on C-5 in 2,3-disubstituted tetrazoliums are acidic, and can be abstracted with butyl lithium.289,290 Tetrazolium methylides, e.g., the dicyano derivative (143), and the phenacyl compound (171, R = Ph, R = Me) are known.291 The latter undergoes an unexpected thermal cyclization reaction to yield imidazolones (173) (Scheme 27).292... 

---