摘要:
                                Reaction of the titanium imido complexes [Ti(NR)((N2Npy)-N-Xyl)(L)] ((N2Npy)-N-Xyl = MeC(2-C5H4N){CH2N(3,5-C6H3Me2)}(2)) with aryl acetylenes afforded the {2+2} cycloaddition products [Ti((N2Npy)-N-Xyl) {kappa(2)-N(Bu-t)CH=CAr}] (Ar = Ph: 1a, Tol: 1b (Tol = 4-C6H4Me)). Complex la was found to insert sulfur and selenium atoms into the Ti-C bond of the strained azatitanacyclobutene unit to give the five-membered metallacyclic systems [Ti((N2Npy)-N-Xyl){kappa(2)-N(Bu-t)CH=C(Ph)E}] (E = S: 2, Se: 3). Likewise, isonitriles were found to insert into the Ti-C bonds to give [Ti((N2Npy)-N-Xyl){kappa(2)-N(Bu-t)CH=C(Ar)C=NR}] (Ar = Ph, R = xylyl: 4, Cy: 5, Bu-t: 6a; Ar = C6H5Me, R = Bu-t: 6b), one example of which (4) has been characterized by X-ray crystallography. The latter species is thought to be a key intermediate in the titanium-mediated three-component coupling of primary amines with acetylenes and isonitriles ("iminoamination"). Reaction of [Ti(N2(Xyl)N(py)){kappa(2)-N(Bu-t)CH=C(Ph)C=NR}] with (BuNH2)-Bu-t gave (BuN)-Bu-t=CHC(Ph)CHNHR, which have been previously identified as the major reaction products in the catalytic aminoamination of alkynes.