- Latent Nucleophilic Carbenes
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Using DFT and ab initio calculations, we demonstrate that noncyclic formamidines can undergo thermal rearrangement into their isomeric aminocarbenes under rather mild conditions. We synthesized the silylformamidine, for which the lowest activation energy in this process was predicted. Experimental studies proved it to serve as a very reactive nucleophilic carbene. The reactions with acetylenes, benzenes, and trifluoromethane proceeded via insertion into sp, sp2, and spCH bonds. The carbene also reacted with the functional groups, such as CHO, COR, and CN at double or triple bonds, displaying high mobility of the trimethylsilyl group. The obtained silylformamidine can be considered as a latent nucleophilic carbene. It can be prepared in bulk quantities, stored, and used when the need arises. Calculation results predict similar behavior for some other silylated formamidines and related compounds.
- Hurieva, Anastasiya,Koidan, Georgyi,Kostyuk, Aleksandr,Kyrylchuk, Andrii A.,Marchenko, Anatoliy,Rozhenko, Alexander B.,Rusanov, Eduard B.,Shvydenko, Kostiantyn
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- Orthoamides, XXXII. - Reactions of tert-Butoxy-N,N,N',N'-tetramethylmethanediamine with NH- and CH-acidic Compounds
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tert-Butoxy-N,N,N',N'-tetramethylmethanediamine (1) reacts with N-formylglycine ethyl ester (2) and with N-formyl-β-alanine ethyl ester (9) to form the aminomethylene compounds 3 and 10, respectively.Glycine ester is aminomethylenated by 1 at the acidic NH2 group to give the amidine 6.Dimethylaminoformaldehyde dimethyl acetal (5) is also suitable for this reaction.On reaction with 1 the compounds 3 as well as 6 yield the amidine 4.N-Monosubstituted formamides are transformed by 1 into formamidines 13.Reaction of isocyanoacetate 17 and 1 affords the enamine 18, whereas reaction of benzyl isonitrile with 1 gives the amidine 19. 2-Alkyl-Δ2-oxazolines 21, carboximidates 23, 25, and amidines 27 are aminomethylenated by 1 to yield the products 22, 24, 26, and 28, respectively.The vinylogous guanidinium salt 34 is obtained by reaction of 1 with N,N,N',N'-tetramethylacetamidinium tetrafluoroborate (31a).Phosphonates 36 react with 1 to afford the enamines 37.The reaction of 1 on ethyl trimethylsilylacetate (39) gives rise to formation of ethyl 3-dimethylaminoacrylate (11).
- Kantlehner, Willi,Wagner, Fritz,Bredereck, Hellmut
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p. 344 - 357
(2007/10/02)
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