Imines silanes

A third photochemical access to silylenes, beside the isomerization of silenes and the photolysis of tri- or cyclopolysilanes, is the irradiation of geminal diazidosilanes, which under nitrogen loss often gives the corresponding divalent silicon species. However, silan-imines are frequent by-products164 or in some cases even the only products (Section IV). 

Allylic silanes also add to imines, in the presence of TiCU, to give amines. ... 

Compared to the cyclic ketones, the coupling of aliphatic aldehydes to prepare 3-substituted indoles was less successful, except for phenyl acetaldehyde, which afforded 3-phenyl indole 83 in 76% yield (Scheme 4.22). The lack of imine formation or the instability of the aliphatic aldehyde towards the reaction conditions may be responsible for the inefficiency of these reactions. Therefore, a suitable aldehyde equivalent was considered. With the facile removal of a 2-trialkylsilyl group from an indole, an acyl silane was tested as a means of preparing 3-substituted indoles. Indeed, coupling of acetyl trimethylsilane with the iodoaniline 24 gave a 2 1 mixture of 2-TMS-indole 84 and indole (85) in a combined 64% yield. Evidently, the reaction conditions did lead to some desilylation. Regardless, the silyl group of 84 was quantitatively removed upon treatment with HC1 to afford indole (85). 

Iridium complexes are known to be generally less active in hydrosilylation reactions when compared to rhodium derivatives, although iridium-based catalysts with bonded chiral carbene ligands have been used successfully in the synthesis of chiral alcohols and amines via hydrosilylation/protodesilylation of ketones [46-52] and imines [53-55], The iridium-catalyzed reaction of acetophenone derivatives with organosubstituted silanes often gives two products (Equation 14.3) ... 

The benzoin reaction typically consists of the homocoupling of two aldehydes, which results in the formation of inherently dimeric compounds, therefore limiting the synthetic utility. The aoss-benzoin reaction has the potential to produce four products, two homocoupled adducts and two cross-benzoin products. Several strategies have been employed to develop a selective cross-benzoin reaction, including the use of donor-acceptor aldehydes, acyl silanes, acyl imines, as well as intramolecular reactions. 

Taking advantage of the acyl silane and imine methodologies, Scheidt and co-workers illustrated the use of acyl silanes 61 and iV-diarylphosphinoylimines 62 to form a-amino ketones 63 (Eq. 4) [55], Utilizing thiazolium pre-catalyst 64, a variety of acyl silanes, both alkyl and aryl, can be coupled efficiently. The reaction conditions are tolerant of various aryl substitutions, providing high yields. 

The development of new methods for the synthesis of homoallylic amine derivatives is an important area of synthetic efforts. Homoallylic amines are extremely important compounds as biologically active molecules [1], The Lewis acid-mediated reactions of imines with allyl silanes are among the most efficient for... 

This silane reacts with electrophiles (e.g., aldehydes, imines. 

Die Dehydrierung von aliphatischen sekundaren Aminen mit Benzolselenigsaure bzw. -anhydrid in Gegenwart von Natrium-cyanid oder von Cyan-trimethyl-silan verlauft uber eine Imin-Zwischenstufe, die durch Addition eines Cyanid-Ions stabilisiert wird2. Dies stellt einen neuen Weg zu a-Alkyl-amino-carbonsaure-nitrilen als Edukte entsprechender a-Alkylamino-carbonsaure-Derivate dar. Aus Dipentyl-amin erhalt man z. B. 2-Pentyl-am ino-hexansaure-am id 3 ... 

Auch aus den Komponenten der Imin-Bildung (z.B. aus 2-Methyl-propanal und tert.-Butylamin) lassen sich durch Reaktion mit Cyan-trimethyl-silan 2-Amino-alkansaure-nitrile (z.B. 2-tert.-Butylamino-3-methyl-butansaure-nitril) herstellen1. 

Bei einer weiteren Variante der reduktiven Beckmann-Umlagerung mit Substitution wird ein Keton-(alkoxycarbonyloxyimin) mit Jod-trimethyl-silan umgesetzt, das so entstandene Carbonsaure-imid-jodid mit einer Grignard-Verbindung in ein Keton-imin umgewandelt und letzteres zum Amin reduziert1. 

High enantioselectivity (ca. 95-99% ee) is observed in this system, better than that revealed in previous reports of the hydrosilylation of imines. The mechanism is as yet unclear however, the authors propose that an active catalyst may be formed by cleavage of the Ti-F bond and generation of a Ti(III) hydride species. Insertion of an imine into the Ti-H bond, followed by a (r-bond metathesis with the silane in a four-centered transition state, may lead to the observed products. Another report on the activity of titanocene complexes as catalysts for the hydrosilylation of aid- and keti-mines also indicates formation of a Ti-H species as catalyst.188 Hydrosilylation proceeds to yield silylamines, with dependence on substitution at nitrogen and on the nature of the ligand bound to the metallocene precursor. 

Non-activated imines have been pentafluorophenylated with (FsCebSiF protonation activates the inline, and chloride ions activate the silane.78... 

Step b Two acid-catalyzed cyclizations ally silane addition to an iminium ion followed by intramolecular imine alkylation and loss of MeOH. 

Nitriles having at least one hydrogen on the functional carbon, react with trimethylchlorosilane under electrochemical conditions to provide a mixture of silazanes and enamines of acylsilanes. These enamines have been suggested to be formed from the isomeric ketene imine form of the nitrile. They were obtained as a mixture of Z (major) and E isomers. Treatment of the silazane-enamine mixture with trimethylchloro-silane/methanol and sodium borohydride followed by neutralization of the salt gives the corresponding RSMA.191... 

Activation by silicon of a P-C-H bond to an intramolecular carbene insertion reaction is exemplified by the silicon-directed Bamford-Stevens reaction.68 For example, thermal decomposition of P-trimethylsilyl /V-aziridinyl imines 72 in toluene (Scheme 8) [with or without Rh2(OAc)4 catalyst] results in the formation of allylic silanes 73 as major or exclusive products by the preferential insertion of the carbene intermediate into the C-H bond P to the silicon substituent. 

This methodology was applied to the asymmetric synthesis of (—)-sedamine (Scheme 10.20). An imine produced in situ from o-anisidine and methyl-5-oxopen-tanoate was alkylated with an enol silane in the presence of silver acetate as catalyst,... 

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