Silyl hydrazine derivatives reaction with

The condition for the formation of isomers is a side-on coordination of the lithium in 47, the lithium derivative of 27. Depending on the bulkiness of the fluorosilane, this side-on coordination makes possible a substitution that is suitable for the system. In comparison, the reaction of lithiated 27 with iPr2SiF2 leads only to the formation of the tris(silyl)hydrazine 75,16 so that kinetic control of the reaction must be supposed ... 

The only known diazasilacyclopropane was synthesized in 1982.56 As shown in Scheme 1, the bulky di-ter -butyl(fluoro)silyl group of the hydrazine derivative A, which is formed on reaction of monolithiated N,N -bis(trimethylsilyl)hydrazine 46 with di-/eri-butyldifluorosilane, reacts with excess 46 with formation of the diazasilyleyclopropane 115. 

Summary Mono(silyl)hydrazines condense to bis(silyl)hydrazines at higher temperature. The degree of oligomerization of mono- and dilithiated silylhydrazines in the crystal depends on the bulkiness of the substituents. Reactions of lithiated silylhydrazines with fluorosilanes lead, for example, to the formation of tetrakis(silyl)-hydrazines, six-, four- and five-membered rings. Formaldehyde derivatives of mono-(silyl)hydrazones are obtained in a reaction of mono(silyl)hydrazines with aqueous formaldehyde solution. 0-Silylpyrazolones can be synthesized by treating mono(silyl)-hydrazines with acetoacetic ester. A dipyrazolonesilane is formed in the reaction of an O-silylpyrazolone with dichlorodimethylsilane. 

The first stable monomeric formaldehyde derivatives are formed by reaction of mono(silyl)hydrazines with aqueous formaldehyde solution. 

Other groups that react with chloromethyleneiminium salts include hydroxylamines, hydrazines, oximes, imines, azines, anhydrides, imides and ketene O-alkyl-O -silyl acetal derivatives however, reactions with these compounds have been relatively infrequent. 

Another route to this cyclohexyl derivative involves the preparation of 6.183 via an olefmation reaction with a substituted phenylalinal derivative followed by reduction of the phenyl ring. The alcohol moiety in 6.183 was converted to the N-phthal-oyl derivative (6.184) by a Mitsunobu inversion.m Conjugate addition with a higher order silyl cuprate gave 6.185. The silyl moiety was converted to an alcohol (6.186) by treatment with tetrafluoroboric acid and then KF/m-chloroperoxy-benzoic acid. Removal of the phthalimidoyl group with hydrazine led to an amino-ester, which cyclized to lactam 5.757.11 Hydrolysis gave 4-amino-5-cyclohexyl-3-hydroxypentanoic acid (6.188) in 60% yield. 

This problem can be surmounted by the use of BTBSH, which affords the (V-silyl hydrazones cleanly and in high yield (eq 3). Thus, iV-silylated aryl and alkyl hydrazones are prepared hy reaction of l,2-bis(t-butyldimethylsilyl)hydrazine with an aldehyde or ketone in the presence of a catalytic amount of Sc(OTf)3 in dichloromethane (eq 3). A number of Lewis acid catalysts were explored, with Sc(OTf)3 being the most effective, giving the hydrazones in yields of up to 95% as mixtures of the syn- and anti-isomers. In the absence of Lewis acid catalysis, the reaction does not proceed. Unlike the simple hydrazine-derived hydrazones, the resulting iV-silyl hydrazones are stable, isolable, and capable of being stored for extended periods of time. 

Finally, diazenes of the formula R3E—N=N—R may also be prepared by dehydrogenation of hydrazines (R3E—NH—NH—R ) with /-butyl-peroxide (31, 32) or chloranil (33) or by the reaction of stannyl derivatives of the above hydrazines with p-benzophenone (16) [Eqs. (7)—(9)] (cf. Table II). Silyl- and germyldiazenes may also be obtained in moderate yields by... 

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