CHEMISTRY OF HYDROGEN ISOCYANIDE .11. A NOVEL REACTION OF THE CYANO-LIGAND OPENING AN ORGANOMETALLIC ROUTE TO 4-AMINO IMIDAZOLES - 4 COMPONENT CONDENSATION (4CC) WITH ISOCYANIDE, ALDEHYDE AND AMINE

Cyano complexes (NEt4[M(CN)(CO)5], M = Cr, Mo, W), isocyanides (CNR1, R1 = Me, Bu(t), Cy, Tol(p)), aldehydes (R2CHO, R2 = e.g. Ph, Tol(p), C 6H4NMe2-p, C6H4Cl-p) and amine hydrochlorides (R3NH3+Cl-, R3 = H, Pr(i ), Ph, Bz) undergo one-pot, four-component condensation type reactions (4CCs) to give the 4-aminoimidazolin-2-ylidene complexes [M(CO)5{CN(H )C(NHR1)C(R2)NR3}] (1-24). These include species which have further be en functionalized in the 5-position by employing heteroaromatic (2-fur anyl, 2-pyrrolyl, 2-thienyl, 2-pyridyl, 2-indenyl) and S-functional (2 -thiomethoxyethyl) aldehydes, as well as dinuclear bisheterocycle-brid ged ones obtained from dialdehydes (propanedial-1,3) or diamines (e.g. 1,2-diaminoethane, 1,4-diaminobenzene), respectively. Hydrazine in th e place of amine gives rise to the carbenoid 1-(N-imino)-4-aminoimidaz oles 25-28, products of the incorporation into the heterocycle of in s itu formed hydrazones as fourth components. The claimed nature of the complexes 1-28 is confirmed by an X-ray structure analysis of 28 which reveals a largely planar five-membered heterocycle with little deloca lization between the Mo-C1(N1)N2-carbene and C7-C8 pi-systems. Mechani stically, the organometallic 4CCs proceed according to their organic a nalogues which lead to hydantoin-4-imides; with H[Co(CN)2(dmgH)2] as a cid component, however, a salt-like product was obtained, the X-ray st ructure analysis of which revealed the presence of an amidinium type c ation made up from the carbonyl, isocyanide and two amine components, and of an unchanged complex cyanocobalt counteranion. Detachment of th e heterocyles from the complex has been achieved either oxidatively wi th KMnO4/Fe(NO3)3 to give the 4-amino-5-hydroxo-imidazolin-2-one 33, o r through substitution with pyridine to give the corresponding C2-H im idazole 34.