Maquenne synthesis

The old Maquenne synthesis of imidazoles [64] is seldom used nowadays. It was originally used to make imidazole-4,5-dicarboxylic acids from tartaric acid dinitrate and either an aliphatic aldehyde or formaldehyde precursor in the presence of ammonium ions at pH 3.5-6.5. The procedure is not an entirely pleasant experience, and has been happily superseded by other approaches, but it may be useful on occasion to make compounds such as vinyl-, hydroxy-and methoxy-substituted 2-arylimidazole-4,5-dicarboxylic acids [65]. Use of dialkyltartrate dinitrates gives the corresponding imidazole-4,5-dicarboxylates in 45-65% yields [31]. 

Allitol was characterized by its melting point, 149-150°, elementary analysis, and by the formation of a dibenzylidene derivative, which, after recrystallization from alcohol, melted at 249-250° on the Maquenne block. Later, Steiger and Reichstein7 repeated this synthesis of allitol and demonstrated the identity of the product with that obtained by the reduction of D-allose. 

Reactions of this type include the major early methods used by Debus,22 Radziszewski,23 Weidenhagen,24 and Maquenne.25 All these suffer from deficiencies such as difficulty of synthesis of starting materials, low yields, and, more often than not, from the formation of mixtures of products which require tedious separation. Among recent modifications26 27 of the Maquenne method is the preparation of dialkyl 4,5-imidazole dicarboxylates in yields of 45-65 % by treatment of a dialkyltartrate dinitrate with either an aliphatic aldehyde or a formaldehyde precursor, in the presence of ammonium ions at pH 3.5-6.5. 

---

See also in sourсe #XX -- [ ]

---