CHIMIE DES METALLOLES DU GROUPE IV. SYNTHESE DE METHYLSILOLES PAR THERMOLYSE D'ESTERS DE SILACYCLOPENTENE-4 OLS-3 ET COMPLEXES η4-FER TRICARBONYLES

Article abstract of DOI:10.1016/0022-328X(85)80300-4

Thermolysis of esters of silacyclopent-4-ene-3-ols Me2<*>CH=CR-CR'(X)<*>H2 (R,R'=H or Me; X=OC(O)NHPh, OC(S)SMe) leads to 1,1-dimethylsilole (1), 1,1,3-trimethylsilole (2) or 1,1,3,4-tetramethylsilole (3).The thermally unstable S-methylxanthates decompose involving both competitive β-C-H and β-C-Si eliminations.With N-phenylcarbamates a regioselective C-H elimination on an endocyclic carbon, leads to the expected siloles 1-3, is mainly observed.A one pot synthesis of 3, the first methylsilole stable as a monomer, from the corresponding alcohol (X=OH, R=R'=Me) and phenyl isocyanate is described. 1,1,3,4-Tetramethylgermole (4) is similarly obtained.The relative stability of the methylsiloles, their ability to form Diels-Alder dimers and to isomerize into a transoid diene, is discussed.In this respect, the strong influence of C-methyl groups on the stabilization of the tetramethylsilole, as in the case of the 1,1,3,4-tetramethylphospholium ion, is made possible.The principal characteristisc of NMR and mass spectra of methylsiloles 1-3 and those of their stable tricarbonyliron complexes are studied.