Aryl isocyanate, carbodiimide, and isocyanide prepared from carbon dioxide. A metathetical group-transfer tale involving a titanium-imide nitterion

摘要

Carbon dioxide can be readily converted quantitatively and under mild conditions into the aryl isocyanate and symmetrical carbodiimide via a metathetical reaction involving a zwitterionic titanium imide (nacnac)Ti=NAr(CH3B(C6F5)(3)) (nacnac(-) = [ArNC((BU)-B-t)](2)CH, Ar = 2,6-(Pr2C6H3)-Pr-i). The metathetical process to generate isocyanates allows also for facile formation of sterically demanding aryl isocyanide, by a deoxygenation route. Labeling studies using enriched (CO2)-C-13 are also described.