Reactivity of frustrated Lewis pairs with BOC protected diazocarboxylates: FLP capture of diazene.

Reactions of (BuOCN) with FLPs are examined. B(CF) interacts with the carbonyl oxygen atoms inducing loss of CHCMe; however, in the presence of basic donors, the protons are intercepted affording the salts [Hbase] [((CF)BOCN)] (base = BuP 1, NCHPh2, HNCHMe3). In contrast, in the presence of (-Tol)P, a proton transfers to the diazo-N atom affording (-Tol)PN(COBu)NHB(CF)4. Further addition of B(CF) to 4 prompts loss of olefin CHCMe and CO affording (-Tol)PNHNHB(CF)5. The course of these reactions is examined by extensive DFT calculations. The nature of 5 is consistent with the FLP reduction of a diazene fragment.