Protection of the amino group

Wolman, Y.

doi:10.1002/9780470771082.ch11

Cited by 6 publications

(3 citation statements)

References 153 publications

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“…To avoid this problem using traditional techniques, the rather expensive amine has been used in large excess, and further purification to remove the starting amine is necessary . Use of N-protecting groups has been a typical way to avert these shortcomings, although they add lengthy synthetic steps in desired transformations …”

Section: Introductionmentioning

confidence: 99%

Cesium Effect: High Chemoselectivity in Direct N-Alkylation of Amines

2002

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A novel method for the mono-N-alkylation of primary amines, diamines, and polyamines was developed using cesium bases in order to prepare secondary amines efficiently. A cesium base not only promoted alkylation of primary amines but also suppressed overalkylations of the produced secondary amines. Various amines, alkyl bromides, and alkyl sulfonates were examined, and the results demonstrated this methodology was highly chemoselective to favor mono-N-alkylation over dialkylation. In particular, use of either sterically demanding substrates or amino acid derivatives afforded the secondary amines exclusively, offering wide applications in peptidomimetic syntheses.

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Section: Introductionmentioning

confidence: 99%

Cesium Effect: High Chemoselectivity in Direct N-Alkylation of Amines

2002

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“…employed, a number of observations have been made recently which seem to indicate that this group is more sensitive to acyl cleavage than had been anticipated (6). Thus, ( A ) : N-carbethoxyphthalimide (1) (Nefkens' reagent (7)) transfers its phthaloyl group at room temperature and p H 7.5 to 6-aminopenicillanic acid (6-APA) to form 2 (8).…”

mentioning

confidence: 99%

Five-membered rings. II. Inter and intramolecular reactions of simple amines with N-substituted phthalimides. Methylamine as a reagent for removal of a phthaloyl group from nitrogen

Wolfe¹,

Hasan²

1970

Can. J. Chem.

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A reexamination of the literature on inter and intramolecular reactions of amines with N-substituted phthalimides has led to the demonstration that methylamine is a convenient reagent for removal of a phthaloyl protecting group from nitrogen at room temperature. Application of this procedure (first described in 1896) to the Gabriel synthesis of primary amines and to peptide synthesis is recommended. The simplicity of the reaction is a consequence of the consecutive occurrence of two unexpectedly rapid processes: (1) methylaminolysis of one of the imide bonds; (2) intramolecular catalysis, by an N-methylamido group, of the hydrolysis or aminolysis of an adjacent phthalamido linkage.Some unsuccessful attempts to prepare 2-aminoethylphthalimide are also described.

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“…Suitable single crystals, decomposing at 466 K, were obtained from acetone. Conversion of (I) to cis-transoid-cisperhydro-3,3,6,6-tetramethylcyclobuta[ 1,2-c: 3,4-c' ]dipyrrole-1,4-dione, (A), was achieved by stirring (I) in CH2C12 in the presence of trifluoroacetic acid (Wolman, 1968) at room temperature. H atoms were included using a riding model (SHELXL97; Sheldrick, 1997), but their displacement parameters were refined freely; rigid methyl groups were allowed to rotate, thus contributing one additional parameter each.…”

Section: Methodsmentioning

confidence: 99%