Synthese von Aminen aus Iminen in der Koordinationssphäre von Silicium – eine überraschende Photoumlagerung von hexakoordinierten Organosilanen

Photo‐Driven Si‐C Bond Cleavage in Hexacoordinate Silicon Complexes

“…The very narrow 29 Si NMR shift range underlines the formation of silicon compounds bearing very similar Si-bound moieties, i.e., compounds comprising the (ONN'O')Si-Ph pattern. On the formation of a minor diasteromeric product in case of 2 and 3 as well as the β-hydride transfer product in case of 3 (δ 29 Si = -114.8 ppm) we have reported earlier [13]. These features can also be found for compound 4, whereas the rearrangement product of 5 reveals only one 29 Si NMR signal, as expected.…”

“…In accord with the exclusive 1,3-shift of the Si-bound alkyl group of 2 and 3 upon UV irradiation under formation of 2a and 3a, respectively [13], in compound 4, which comprises a sterically more ____________ * Dr. J. Wagler demanding alkyl substituent (i.e., a cyclohexyl group) the 1,3-alkyl shift is still favored.…”

“…For 2a-8a (not applicable for 5a) the diastereomer with swapped positions R' vs. Ph was observed 29 Si NMR spectroscopically as a minor component (< 10 %) of the reaction mixture. For 3a and 4a the product of β-hydride transfer (R' = H) was also observed NMR spectroscopically as a minor component (< 10%) [13]. Table 1.…”

“…13 C NMR shifts (δ in ppm relative to SiMe4) of the (Ph,Aryl,N,R)-substituted carbon atoms detected in the product mixture after irradiation of the hexacoordinate diorganosilicon compounds 2-9, 11 and 16.…”

“…Our recent research on hypercoordinate diorganosilanes [12] revealed remarkably activated Si−C bonds, which, upon irradiation, are cleaved to yield a novel ligand moiety coordinated to the silicon atom (Scheme 1) [13]. Hexacoordination of the silicon atom was shown to be one of the keys to this reactivity pattern since pentacoordinate silicon compounds comprising related ligand backbones proved inert under similar reaction conditions [14].…”