Stephen S. Washburne

Facile preparation of silyl azides with dipolar aprotic solvents

Abstract The reaction of sodium azide with chlorosilanes in hexamethylphosphoric triamide or dimethylformamide at room temperature affords a high yield preparation of silyl azides, e.g. Me3SiN3,Me2Si(N3)2, PhMeSi(N3)2 and Ph2Si(N3)2. For characterization, the azides may be converted to silyphosphiimies, R3Si-N=PPh3.

Cycloaddition reactions of metal azides. Ferrocenyltetrazole via a silyl azide

Abstract Reaction of cyanoferrocene with trimethylsilyl azide and aluminum chloride in refluxing o-dichlorobenzene gave ferrocenyltetrazole as the sole organometallic product. Other aryl nitriles react with silyl azides without added aluminum chloride to give tetrazole,3,5-diaryl-1,2,4-triazole, and 3,6-diaryl-1,2,4,5-tetrazine. Mechanisms for these transformations are proposed.

Chloraminosilanes II. Preparation and spectroscopic studies on alkyl-(dimethylamino)chlorosilanes

Abstract Several new compounds containing both chloro and dimethylamino groups linked to silicon have been prepared. The general method involved reacting a solution of the appropriate polychlorosilane in ether at ca . - 50° with a chilled ethereal solution of dimethylamine. Prepared in this fashion were CH 3 Si(NMe 2 )Cl 2 , CH 3 Si(NMe 2 ) 2 -Cl, PhSi(NMe 2 )Cl 2 , PhSi(NMe 2 ) 2 Cl, CH 3 (H)Si(NMe 2 )Cl, (CH 3 ) 2 Si(NMe 2 )Cl, CH 2 CH(CH 3 )Si(NMe 2 )Cl, and Ph 2 Si(NMe 2 )Cl. Comparison of the spectra of these compounds with those in the perhalo and peramine series showed that replacement of NMe 2 for Cl resulted in an upfield shift of the resonances of the other groups linked to silicon, a shift which parallels that observed upon substitution of CH 3 for Cl. The relationship of ν(SiH) in the IR and δ(SiH) in the NMR spectra was linear.

Reaction of trimethylsilyl azide with bridged bicyclic olefins

Abstract Bridged bicyclic olefins were found to undergo facile 1,3-cycloaddition reaction with trimethylsilyl azide. Norbornene produced cis,exo -1-trimethylsilyl-4,7-methano-3a,4,5,6,7,7a-hexahydrobenzotriazole, while norbornadiene formed a diadduct with cis,exo -stereochemistry, together with 2-trimethylsilyl-1,2,3-triazole produced by a retro-Diels—Alder reaction of an intermediate mono-adduct. Dicyclopentadiene reacted only at the norbornene position while α-pinene did not react with trimethylsilyl azide. In contrast to aryl- and sulfonyl-azide adducts of norbornene derivatives, which decompose upon heating the present adducts were recovered unchanged after prolonged treatment at 205°C.

Acetolysis of 4,4-disubstituted 4-silacyclohexyl tosylates: effect of remote silicon substitution on organic reactivity

Abstract 4,4-Dimethyl-(Ia), 4,4-diphenyl-(Ib), and phenyl-methyl-substituted 4-silacyclohexyl tosylates (IcId) were compared with isosteric 4,4-disubstituted cyclohexyl tosylates. The rates of acetolysis of the silatosylates were three to five times greater than those of the carbocyclic analogs. With the exception of Ia, which largely fragmented to di-4-pentenyltetramethyldisiloxane, the acetolysis products of compounds I were acetates and olefins in proportions similar to that observed for cyclohexyl tosylates. It is concluded that the kinetic and product-determining effect of a γ-silyl substituent on a tosylate is slight, although where a stabilized β-silylcarbonium ion can form by rearrangement, such as with Ia, fragmentation products will predominate.

Fragmentation of the silacyclohexane ring

Abstract The title reaction proceeds in dichloromethane with a pseudo-first-order rate constant of 1.19 x 10 − 3 sec − , 5000 times faster than the reaction of trityl fluoroborate with tetraethylsilane, yielding as products 4-pentenyldimethylfluorosilane, triphenylmethane, aand boron trifluoride. The enhanced reactivity of the title silane is attributable to σπ conjugation.