Diazomethane umpolung atop anthracene: an electrophilic methylene transfer reagent

Formal addition of diazomethane's terminal nitrogen atom to the 9,10-positions of anthracene yields H(2)CN(2)A (1, A = C(14)H(10) or anthracene). The synthesis of this hydrazone is reported from Carpino's hydrazine H(2)N(2)A through treatment with paraformaldehyde. Compound 1 has been found to be an easy-to-handle solid that does not exhibit dangerous heat or shock sensitivity. Effective umpolung of the diazomethane unit imbues 1 with electrophilicity at the methylene carbon center. Its reactivity with nucleophiles such as H(2)CPPh(3) and N-heterocyclic carbenes is exploited for C[double bond, length as m-dash]C bond formation with elimination of dinitrogen and anthracene. Similarly, 1 is demonstrated to deliver methylene to a nucleophilic singlet d(2) transition metal center, W(ODipp)(4) (2), to generate the robust methylidene complex [2[double bond, length as m-dash]CH(2)]. This behavior is contrasted with that of the Wittig reagent H(2)CPPh(3), a more traditional and Brønsted basic methylene source that upon exposure to 2 contrastingly forms the methylidyne salt [MePPh(3)][2[triple bond, length as m-dash]CH].