Edmunds Lukevics

ADDITION OF NITRILE OXIDES TO GERMYL-SUBSTITUTED ETHYLENES

The reactions of [2+3] cycloaddition of nitrile oxides to mono- and 1,2-disubstituted germylalkenes proceed regioselectively and resulted 5-Ge-substituted isoxazolines-2 from triethylvinyl- and triethylallylgermane and 4-Ge-isomers from β -triorganylgermylstyrene and ethyl triorganylgermylacrylates. In the latter case the reaction occurs stereospecifically: Z -germylalkenes give cis - , while E -germylalkenes yield trans -4,5-substituted isoxazolines. The structure of products obtained was determined by 1 H-NMR spectroscopy and for 11a confirmed by single-crystal X-ray analysis.

Synthesis of new vinylsilanes containing an asymmetric silicon via platinum catalyzed hydrosilylation of acetylene and monosubstituted alkynes

Abstract A series of new racemic vinylsilanes has been obtained by hydrosilylation reaction of acetylene and monosubstituted alkynes with (±)-α-NpPhMeSiH and (±)-N(CH 2 CH 2 O) 3 SiCH 2 PhMeSiH in the presence of platinum-containing catalysts.

Reaction of heteryl-silanes and -germanes with metal hydrides

Abstract A series of heteryl-silanes and -germanes 1 containing a different number of dihydrofuryl and dihydropyranyl groups at the metal atom has been obtained by means of the lithium synthesis. Subsequent substitution of heteryl group for hydride ion occurs during the reaction of the compounds formed with LiAlH4. The hydrides and boron hydrides of lithium and sodium are able to eliminate the dihydrofuryl group from the most reactive bis[2-(4,5-dihydrofuryl)]methyl-silane (7). The reaction of tris-heteryl-silanes and -germanes with LiAlH4 gives [2-(4,5-dihydrofuryl)]methylsilane (12), [2-(5,6-dihydro-4H-pyranyl)]methylsilane (14) and [2-(4,5-dihydrofuryl)]methylgermane (13) in good yields, which are otherwise difficult to obtain.

Indirect nuclear spin–spin coupling constants of nitrogen-15 to silicon-29 in silylamines

The 15N–29Si spin–spin coupling constants in silylamines have been measured from 29Si satellites in their natural abundance 15N n.m.r. spectra in an INEPT sequence for accumulation of signals and interpreted in terms of Fermi-contact interaction; the sensitivity of 1J(15N–29Si) to dπ–pπ bonding was noted.

Phase-transfer catalysis in reduction by lithium aluminium hydride

Ketones, alky and aryl halides, nitriles, and amides undergo reduction with lithium aluminium hydride in the solid LiAlH4–hydrocarbon two-phase system in the presence of typical phase-transfer catalysts (crown ethers and quaternary ammonium salts), the reaction being characterized by good yields; solubilization of lithium aluminium hydride in non-polar solvents is demonstrated.