Benzylimidazole-5-carbaldehyde

A stirred solution of l-benzyl-5-hydroxymethylimidazole (0.79 g, 4.2 mmol) and activated manganese dioxide (3.6 g, 41 mmol) in dioxan (25 ml) is refluxed 

Reductive procedures are seldom sufficiently specific to give high yields of pure aldehydes, and so it is customary to reduce an ester function with lithium aluminium hydride to hydroxymethyl and then reoxidize [11]. A range of 1-substituted 4,5-dicarbethoxyimidazoles have been reduced to the 4,5-bis(hydroxymethyl) derivatives in 50 88% yields oxidation to the bis-aldehydes is reported with 35-45% efficiency [8]. 

Other synthetic approaches include ring synthesis of 1,3-disubstituted iniidazolium-2-carbaldehydes (see Section 3.1.1) and the conversion of 

---

Most usual oxidizing agents act normally with imidazole aldehydes and ketones but l-benzylimidazole-2-carbaldehyde is reportedly somewhat resistant to selenium dioxide oxidation. Reduction of ketone functions under Clemmensen and Wolfi-Kischner conditions is usually successful. Zinc dust and acetic acid reduce acetyl groups to a mixture of secondary alcohol and ethyl borohydride gives the alcohol exclusively (B-76MI40701). 

---