Silylaminos

I) By treating bis(silylamino)difluorosilanes [1] with four equivalents of f-BuLi, thf, and [12] crown-4 lithium(lithiosilyldiamides) (1), salts with a cyclic (Li Si)" anion are obtained [2]. In the reaction with two equivalents of r-BuLi, dilithiated derivatives (type 2) are formed [1-3]. 

Morton, D.W. and Neilson, R.H., Reactions of (silylamino)phosphines with ketones and aldehydes, Organometallics, 1, 289, 1982. 

Many simple oxidation reactions of tertiary alkyl or aryl phosphines are less straightforward in phosphines with silylamino substituents 1 °... 

Other N-silyIphosphinimines which are also suitably constructed phosphazene precursors, can be prepared by a second oxidation reaction of silylamino-phosphines. When these phosphines react with carbon tetrachloride, two types of P-chlorophosphiminines may be formed by essentially two pathways (eq 7) ( ). 

An alternate pathway is possible for systems containing silylamino substituents at phosphorus. This most likely involves attack of the CCl3 anion at the electrophilic silicon resulting in elimination of Me3SiCCl3 as shown in pathway B. In the systems investigated thus far, the reaction pathway preference appears to be influenced by (1) solvent polarity, and (2) steric and electronic effects of the substituents at phosphorus ( ). 

Recently, density functional calculations (B3LYP) on the thermal rearrangement of tris(silyl)hydroxylamines to silylamino disiloxane for model compounds concluded that the insertion of a silyl group into the N—O bond is energetically favoured if it occurs from the nitrogen atom. ... 

If the central silicon carries two silylamino groups, only half an equivalent of the iminosilene undergoes migration of a methanide ion. The result is a cross dimer of the two ylides,25 as shown in Scheme 9.15... 

Cyclodisilazane anions and cyclodisilazanes in cw-conformation are found in the reaction of dilithiated bis(silylamino)fluorosilanes with chlorotrimethylsilane. The dilithium salt of the corresponding bis(silylamino)chlorosilane is obtained. LiCl elimination in the presence of THF leads to the formation of silaamidides (which are isolated as dimers),19,26 four-membered cyclodisilazane anions and (thf)3Li-Cl-Li(thf)36 or Li(thf)/ cations (Scheme 10).19,27 Hydrolysis of dimeric silaamidides is a facile synthesis leading to cyclodisilazanes in the cw-conformation. Examples are shown in Figs. 1 and 2 (Scheme 11).19,27... 

Moreover, it must be noted that silylation has still great synthetic potential because of its easy availability and good yields. Thus, using silyl esters259 is very advantageous for a peptide synthesis without racemisation. The treatment of Z-amino acids or Z-peptides (as p-nitrophenylesters (492)) with N-silylamino acid TMS-esters (493) leads to Z-peptide-TMS-esters (494) and after subsequent hydrolysis to Z-peptides (495) in excellent yields (Scheme 71). 

Compounds containing the Si-N-P linkage combine the structural and stereochemical diversity of phosphorus with the reactivity of the silicon-nitrogen bond. Indeed, much of the derivative chemistry and synthetic potential of these compounds, especially the (silylamino)phosphines such as (Me3Si)2NPMe2, is based on this difunctional character. We report here a general, "one-pot" synthesis of (silylamino)phos-phines and describe their use in the preparation of several types of phosphorus-containing materials. 

Synthesis of (Silylamino)phosphines. In a typical preparation, addition of one molar equivalent of PCI3 to a stirred solution of LiN(SiMe3)2 in ether at -78°C followed by one or two equivalents of an alkyl Grignard or lithium reagent at 0°C gives the corresponding mono- or dialkylphosphine. This proce-... 

Nucleophilic Reactions of (Silylamino)phosphines. The reactions of (silylamino)phosphines with simple aldehydes and ketones proceed via nucleophilic attack by phosphorus followed by a [1,4] silyl migration from nitrogen to oxygen to yield new N-silylphosphinimines ( 3). With a,B-unsaturated carbonyl compounds, 1,4-addi-... 

Silylamino)phosphines also react with various halides including ethyl bromoacetate, allyl bromide, and chloroformates. The initially-formed phosphonium salts eliminate silyl halides to afford functionalized phosphinimines Me3SiN=P (R)Me2 where R = -CH2C(0)0Et,... 

Two-coordinate (Silylamino)phosphines. Certain chloro(silylamino)phosphines bearing a trimethylsilyl-methyl group can be dehydrohalogenated to yield stable (methylene)phosphines. The very low field (6 309.9) shift confirms the two-coordinate nature of this compound while the low field (6 7.09) signal shows it to be the P=CH rather than the P=N isomer. Three modes of reactivity of this (methylene)phosphine have been observed addition to the P=C bond, oxidative... 

Silylamino)phosphines with P-H Bonds. Treatment of sterically crowded chloro(silylamino)phosphines with i -PrMgCl yields, unexpectedly, the P-H derivatives in a process which must involve hydride donation by the Grignard reagent. Typically, the P-H phosphines are formed along with varying amounts of the expected... 

The (benzoyl-trimethyl-silylamino(phenyl-trimethyl-silyl-phosphano) methylene) phenylphosphane was heated in acetonitrile to 80-90°C. A cyclic product was formed, which readily crystallized and turned out to be of a Z-structure according to the CIP rules ... 

These a-silylamino- and a-silylamido-2,5-cyclohexadien-l-one have been submitted to SET photochemistry (see Sections IV.C.7 and VI.B.7) to synthesize functional hydroisoquinolines.301... 

This SET-induced photocondensation has been used to internally cyclize enones bearing the a-silylamino functionality in the molecule. This leads to cyclic, bicyclic and spirobicyclic compounds.82,338... 

Photocyclization of enones substituted by an a-silylamino group. Irradiation (>320 nm) of these substrates with DCA as sensitizer results in N-heterocycles. 

Eine anionische Variante" dieser Isosterengruppe findet sich in den deprotonierten Silylamino-silylimino-diorgano-phosphoranen der allge-meinen Formel (14) ... 

Silylamino-silylimino-phosphorane der allgemeinen Formel R3SiNH— —PR2=NSiR3 83> 141> 142> mit Aluminiumalkylen zur Reaktion gebracht werden 83> ... 

Methyl-1 -(N-phenyl-N-trimethyl-silylamino)-propene (214) H Me Me PhN(SiMe3)2... 

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