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

Reactions of (tBuO(2)CN)(2) with FLPs are examined. B(C6F5)(3) interacts with the carbonyl oxygen atoms inducing loss of CH2=CMe2; however, in the presence of basic donors, the protons are intercepted affording the salts [Hbase](2) [((C6F5)(3)BO2CN)(2)] (base = tBu(3)P 1, NC(5)H(2)Ph(3)2, HNC(5)H(6)Me(4)3). In contrast, in the presence of (o-Tol)(3)P, a proton transfers to the diazo-N atom affording (o-Tol)(3)PN(CO(2)tBu)NHB(C6F5)(3)4. Further addition of B(C6F5)(3) to 4 prompts loss of olefin CH2=CMe2 and CO2 affording (o-Tol)(3)PNHNHB(C6F5)(3)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.