The sweet smell of isonitriles

Despite their versatility in a number of chemical transformations, isonitriles have generally been shunned as synthetic reagents. Few isonitriles are commercially available, and the most common way to prepare the functional group usually requires hazardous reagents like phosgene. But chemists who work with isonitriles will tell you there's a bigger obstacle in developing their chemistry: Isonitriles stink. Their stench has been described as "horrible" and "extremely distressing." They've been patented for use as nonlethal weapons. Now, thanks to a new family of fragrant isonitriles developed by researchers at the University of California, Riverside, chemists can use isonitriles without the olfactory assault (J. Am. Chem. Soc. 2006, 128, 11772). Michael C. Pirrung and Subir Ghorai treated oxazole or benzoxazole with n-butyllithium and various acyl chlorides to generate a series of (Z)-isocyanovinyl esters (shown) and 2-isocyanylphenyl esters, which smell of mild isonitrile at their worst and like taffy or cherry at their best. The sweet-smelling compounds are easy to make and react just like their malodorous cousins.