Silylimines

As an alternative method, poly(cyclodiborazane)s were prepared by the reaction of bis(silylimine)s with chlorodialkylboranes or with methyl dialkylborinates (scheme 18).32 This reaction proceeds via the condensation between V-silylimine and boron halide, eliminating trimethylsilyl halide followed by dimerization. However, the isolated polymer became insoluble after several hours of exposure under air, which resulted from the cross-linking reactions of unreacted trimethylsilyl groups to form trimerized hydrobenzamide derivatives. 

Silylimines fi-lactams.1 This lithium amide converts aldehydes, even enol-izable ones, into silylimines. Thus acetaldehyde can be converted into the imine (2), which cannot be isolated but which reacts with lithium ester enolates to form... 

Photochemical hydrogen abstraction reaction for the silylimine 161 give an o-quinodimethane intermediate 162 which could be trapped with dimethyl fumarate, dimethyl maleate, trans-methyl cinnamate, methyl acrylate, acrylonitrile (equation 94)... 

Special cases concerning the reactivity of intermediate 331 with electrophiles involve the use of A -silylimine or epoxides. In the first case, aminoalcohol 333 was prepared, which was easily cyclized (thionyl chloride followed by basic treatment) to the corresponding substituted tetrahydroisoquinoline 334 (Scheme 98) . ... 

N-NMR measurements prove that the electron density at the nitrogen atom is smaller in silylimines than in organylimines. Silyliminosilenes are usually obtained in dimeric form.19,21,22... 

A catalytic asymmetric in situ reduction of N-H imines has been achieved in a sequence in which trifluoroacetophenones, ArCOCF3, are first converted to silylimines [using LiN(SiMe3)2], and then on to give trifluoromethylated amine salts, Ar-C(CF3)-NH2.HC1, in good to excellent yield and ee.5s The intermediate N-H imines can be isolated via methanolysis of the N-Si bond, while the enantioselective reduction can be carried out using a chiral borane auxiliary. 

Polymer-supported azomethine ylids generated from a-silylimines through a 1,2-silatropic shift, are shown to be versatile reagents suitable for the synthesis of libraries of pyrrolidine derivatives after 1,3-dipolar cycloaddition with a series of dipolarophiles. Effectively substituents R1, R2 and dipolarophiles A=B and A=B can be chosen to get the desired adduct.146... 

Optically active p-lactams.2 The reaction of the enolate of /-butyl butanoate with the optically active silylimine 2, prepared from silylated 1, provides the optically active p-lactam 3. The optical purity and configuration of 3 was established by conversion to the antibiotic carbapenem ( + )-PS-5 (4). 

Optically active TV-sulfonylamino alcohols derived from D-camphor or norephedrine were found to be efficient chiral ligands for the enantioselective allylboration of iV-silylimines (Equation (170)) 646-648 B-Allyl(diisopinocampheyl)borane allylated iV-diisobutylaluminum imines with 87% ee (Equation (171)).649,650... 

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