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METALLOLES-14 CHEMISTRY
Authors:J Dubac  A Laporterie  G Manuel  H Iloughmane
Institution:Laboratoire des Organométalliques, Equipe de Recherche Associée au C.N.R.S. , Université Paul-Sabatier , U.A. N° 477, 118 route de Narbonne, 31062, Toulouse Cédex, France
Abstract:Abstract

In order to obtain β-functionalized 1-sila (or germa)-cyclopent-2-enes  /></span>(M = Si, Ge; R<sup>1</sup>, R<sup>2</sup> = Me or Ph; R<sup>3</sup>, R<sup>4</sup> = H or Me) (I) various oxidation methods of metallacyclopent-3-enes have been examinated. The resulting metallacyclopent-4-ene-3-ols (I, X = OH) were converted into phenylcarbamates (I = OC(O)NHPh) or S-methylxanthates (I = OC(S)SMe) and their utility as intermediates in the synthesis of metalloles (siloles and germoles) was investigated.</p> Depending on the experimental conditions, catalytic dehydration of metallacyclopentenols or thermolysis of carbamates or xanthates give various dienes via four different reaction processes: i) β-elimination C-M; ii) β-elimination C-H; iii) isomerization of C-methylated metalloles; iv) catalytic demetallation.</p> The thermolysis of arylcarbamates is the best method for conversion of I to metalloles, specially for the synthesis of remarkably dimerization-stable 1,1-R<sup>1</sup>R<sup>2</sup>-3,4-dimethylmetalloles (≥ 80% yield). A one pot synthesis of these stable metalloles from the corresponding alcohol and phenyl isocyanate is proposed.</p> Unstable monomeric metalloles are stabilized by transition metal complexes or trapped by a (4 + 2) cycloaddition.</td>
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Keywords:α-Metallated N  N-dimethylsulfonamides  4-t-butylcyclohexanone  N  N-dimethylamides of β-hydroxysulfonic acids  aldol reaction  stereochemistry  axial (equatorial) attack
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