227025-42-5Relevant articles and documents
Hydrogen/deuterium exchange reactions and transfer hydrogenations catalyzed by [C5Me5Rh(olefin)2] complexes: Conversion of alkoxysilanes to silyl enolates
Lenges, Christian P.,White, Peter S.,Brookhart, Maurice
, p. 4385 - 4396 (1999)
A series of [C5Me5Rh(CH2=CHR)2] complexes (1a-e) have been prepared in which the olefin bears a bulky silyl substituent, R = (a) SiMe3, (b) SiMe2OEt, (c) Si(OiPr)3, (d) SiMe(OSiMe3)2, (e) SiPh2Oi-Pr. The solid-state structure of 1c has been determined by X-ray crystallography. When complex 1a is heated (50°C) in deuterated solvents (C6D6, C6D5CD3, C6D5Cl, or (CD3)2CO), deuterium is incorporated into the olefinic sites. Thermolysis at higher temperatures results in further H/D exchange and deuteration of both the SiMe3 and C5Me5 groups. Heating 1a in C6D6 with added substrates (aniline, MeOtBu, MeOSiMe3, Cp2Fe, cyclopentene, or EtOAc) results in deuteration of these substrates via shuttling of deuterium from C6D6 to the olefinic sites and then into certain sites of the substrates. Thermolysis of 1a in the presence of vinyltrimethylsilane at higher temperatures results in C-Si bond cleavage and generation of a silacyclopentadiene complex (6) whose structure was determined by X-ray analysis. Thermolysis of 1c in C6D6 results in facile H/D exchange and incorporation of deuterium not only into the vinylic positions but also into the methine and methyl groups of the isopropyl substituents. At 90°C in the presence of CH2=CHSi(OiPr)3 a catalytic transfer hydrogenation is observed which converts the vinylsilane to the silyl enolate, Et(iPrO)2SiOCMe=CH2. A series of catalytic transfer hydrogenations were carried out in which alkoxysilanes CH2=CHSiMe2OR (R = Et, n-Bu, CHMeEt, C2H4tBu, C2H4Ph, CHMePh, CHMeCH2Ph) were converted to the corresponding silyl enolates. Catalytic conversion of the vinylaminosilane CH2=CHSiMe2NHC2H4Ph to the silyl enamine EtSiMe2NHC2H2Ph is also reported.
