- Alkoxide activation of aminoboranes towards selective amination
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Piece of the (inter)action: The interaction of alkoxides with the sp 2 Bpin (pin=pinacol) moiety in aminoboranes forms the in situ Lewis acid-base adduct [RO-→B(OR)2-N(R′)2] which enables the amino moiety to react as a strong nucleophile with several electrophiles, thus providing amino alcohols, β-enamino esters, and β-hydroxy amides in a direct and remarkably selective way (see scheme). Copyright
- Sole, Cristina,Fernandez, Elena
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supporting information
p. 11351 - 11355
(2013/11/06)
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- Reactions of phenyldimethylsilyllithium with β-N,N- dimethylaminoenones: A convenient synthesis of β-dimethyl(phenyl) silylacrylic acid and its derivatives
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Phenyldimethylsilyllithium reacted with 5,5-dimethyl-3-(N,N,-dimethylamino) cyclohex-2-enone (7), 3-(E)-N,N-dimethylaminopropenal (11), and 4-N,N-dimethylaminobut-3-en-2-one (13) to give the corresponding β-silyl-α,β-unsaturated carbonyl compounds 8, 12, and 14, in which the dimethylamino group has been displaced by the phenyldimethylsilyl group. Phenyldimethylsilyllithium reacted with ethyl β-N,N- dimethylaminopropenoate (15) by conjugate addition, but, in contrast to the ketones 7 and 13 and the aldehyde 11, the intermediate enolate 16 was C-protonated in the aqueous work-up to give ethyl 3-N,N-dimethylamino-3- dimethyl(phenyl)silylpropanoate (17). When the enolate 16 was instead given a mysteriously brief treatment with methyl iodide before work-up, the product was ethyl 3-(E)-dimethy(phenyl)silylpropenoate (18). Phenyllithium and methyllithium also added conjugatively to ethyl β-N,N-dimethylaminoacrylate (15) but, in contrast to the silyl case, the intermediate enolate 22 reacted unexceptionally with methyl iodide to give the products 25 and 26 of stereoselective C-methylation. This synthesis of the ester 18 was used to synthesize the Oppolzer sultam derivative 30.
- Fleming, Ian,Marangon, Elena,Roni, Chiara,Russell, Matthew G.,Chamudis, Sandra Taliansky
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p. 325 - 332
(2007/10/03)
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- New synthesis of β-aminoacid derivatives via hydroamination in Dimcarb
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A new selective hydro-dimethylamination method for unsaturated carboxylic acid derivatives with the pronucleophilic dimethylamine-precursor Dimcarb is described, which allows effective synthesis of hydro-β-dimethylamino-acid derivatives and unsaturated amides. Simple HMO quantum chemical calculation together with 1H NMR examination permits the prediction of suitable substrates, coupling position for dimethylamine as well as for mechanistical insights and optimal reaction course.
- Hess,Dunkel,Muller
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p. 591 - 597
(2007/10/02)
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