Categories: C-N Bond Formation > Synthesis of substituted N-heterocycles >
N-acylation
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In ionic liquids [Bmim][PF6] or [Bmim][BF4], a highly regioselective
N-substitution of pyrrole with alkyl halides, sulfonyl chlorides, and benzoyl
chloride gave substituted pyrroles in excellent yields. Michael addition of
pyrrole with electrophilic olefins was completed in a highly regioselective
manner to afford N-alkylpyrroles.
Z.-G. Lea, Z.-C. Chen, Y. Hu, Q.-G. Zheng Synthesis,
2004,
1951-1954.
In an electrochemical method for the selective N1-acylation of indazoles, indazoles
are reduced to indazole anions and H2. A subsequent reaction with acid anhydrides results in selective acylation of the
N1-position. This procedure can also be applied to the acylation of
benzimidazoles and indoles.
D. M. M. M. Dissanayake, A. J. Vannucci, Org. Lett., 2019, 21,
457-460.
An improved one-pot procedure for the preparation of N-acylbenzotriazoles
involves mild reaction conditions and allows the preparation of several
derivatives not accessible by the previously reported methods.
A. R. Katritzky, N. Kirichenko, B. V. Rogovoy, Synthesis,
2003, 2777-2780.
Readily available N-acylbenzotriazoles efficiently acylate aqueous
ammonia and primary and secondary amines to give primary, secondary, and
tertiary amides in very good yields.
A. R. Katritzky, H.-Y. He, K. Suzuki, J. Org. Chem., 2000,
65, 8210-8213.
A convenient reaction of carboxylic acids with 1H-benzotriazole provides N-acylbenzotriazoles
in good yields in the presence of only 0.35 equivalent of trichloroisocyanuric
acid and 1.2 equivalents of PPh3.
M. Singh, A. S. Singh, N. Mishra, A. K. Agrahari, V. K. Tiwari, Synthesis, 2019, 51,
2183-2190.
The combination of 2,2′-dipyridyl disulfide and PPh3 enables the
conversion of carboxylic acids into the corresponding N-acylbenzotriazoles
in the presence of 1H-benzotriazole. This base-free reaction offers mild
conditions, short reaction time, and wide substrate scope.
A. S. Singh, A. K. Agrahari, N. Mishra, M. Singh, V. K. Tiwari, Synthesis, 2019, 51,
470-476.