1 -Dimethylamino-1 -phenyl-2-trimethylsilyl

Recently the first examples of divalent organotin compounds in which intramolecular coordination as such is sufficient for stabilization were reported. These compounds are bis(2-[(dimethylamino)methyl]phenyl tin(II), 6 (74) bis(2-[l-(dimethylamino)ethyl]phenyl tin(II), 7 (78) bis[8-(dimethylamino)-l-naphthyl]tin(II), 8 (75) bis([2-(dimethylamino) phenyl (trimethylsilyl)methyl tin(II), 9 (78) and bis[(2-pyridyl)bis(tri-methylsilyl)methyl]tin(II), 10 (79) and are schematically shown in Fig. 5. 

Cp pentamethylcyclopentadienyl Tmp 2,2,6,6-tetramethylpiperidine Dipp 2,6-di(iso-propyl)phenyl Trip 2,4,6-tri(iso-propyl)phenyl Mes 2,4,6-trimethylphenyl Mes 2,4,6-tri(tert-butyl)phenyl Ada adamantyl dmap 4-(dimethylamino)pyridine Tms trimethylsilyl (SiMe3)... 

Two additional cationic complexes were recently reported, 163 and 164, prepared by the reaction of trimethylsilyl triflate with bis[2-((dimethylamino)methyl)phenyl]silane (165)... 

Of course, under many conditions, the preformed enolate aldol reaction appears to be significantly exothermic. The additional driving force is presumably provided by the enthalpy of coordination of the ambident aldolate ion with a cation. The importance of cation solvation in providing a driving force for the aldol reaction has been elegantly demonstrated by Noyori and coworkers.In this important experiment, the tris(dimethylamino)sulfonium (TAS" ) enolate of l-phenyl-2-propanone was prepared as shown in equation (6). The naked enolate was obtained as a yellow crystalline material, free of trimethylsilyl fluoride, by concentration of the THF solution. 

Summary Using a new synthetic pathway, four intramolecularly donor-stabilized silenes, R(Me3Si)Si=C(SiMe3)2 (10 R = 8-dimethylamino-l-naphthyl 11 R = 2 -(dimethylaminomethyl)phenyl 14 R = 2,6-bis(dimethylaminomethyl)phenyl 15 R = 2,6-bis(diethylaminomethyl)phenyl)), were prepared by the reaction of (dichloromethyl)tris(trimethylsilyl)silane (Ic) with the respective dialkylamino substituted aryllithium compounds (molar ratio 1 2). X-ray structural analyses of the four silenes revealed strong donor-acceptor interactions between the dialkylamino groups and the electrophilic silene silicon atoms, leading to pyramidalization at the silicon centers. The configuration at the silene carbon atoms was found to be planar. The chemical behavior of the new silenes, particularly reactions with water and methanol, treatment with methyl iodide or methyl triflate and conversions with benzaldehyde, are discussed. 

ClgHgyNyPjSift, Methyl-[tris(dimethylamino)phosphonium]amino -tris-(trimethylsilyl-amino)-trimethylsilyl-iminophosphoranide, 456, 751 C20H13O4P, 1-Phenyl-1,1 -spirobi(3H-2,1-benzoxaphosphole)-3,3 -dione, 446, 627... 

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