A metal-free transamidation of tertiary amides bearing an N-electron-withdrawing substituent provides primary amides in good yield in the presence of (NH4)2CO3 in DMSO at 25 °C. In addition, N-tosylated lactam derivatives afforded their corresponding N-tosylamido alkyl amide products.
J. Chen, Y. Xia, S. Lee, Org. Lett., 2020, 22, 3504-3508.
In the presence of a catalytic amount of L-proline, transamidations of carboxamides with amines were achieved under solvent-free conditions. The reaction tolerates a wide range of amines.
S. N. Rao, D. C. Mohan, S. Admurthy, Org. Lett., 2013, 15, 1496-1499.
[Ni(quin)2] catalyzes the N-formylation and N-acylation of amines using N,N-dimethylformamide and N,N-dimethylacetamide in the presence of imidazole in good yields. The protocol shows broad substrate scope for aliphatic, aromatic, and heterocyclic amines.
R. B. Sonawane, N. K. Rasal, S. V. Jagtap, Org. Lett., 2017, 19, 2078-2081.
A highly efficient transamidation of several primary, secondary, and tertiary amides with aliphatic and aromatic amines (primary and secondary) is performed in the presence of a 5 mol % concentration of different hydrated salts of Fe(III). The methodology was also applied to urea and phthalimide to demonstrate its versatility and wide substrate scope. A plausible mechanism explains the crucial role of water.
L. Becerra-Figueroa , A. Ojeda-Porras, D. Gamba-Sánchez, J. Org. Chem., 2014, 79, 4544-4552.
The use of potassium tert-butoxide enables transamidation of primary and tertiary amides with a range of aryl, heteroaryl, and aliphatic amines at room temperature under transition-metal-free conditions to provide secondary amides in high yields. Moreover, the reaction of cyclopropyl amine with tertiary amides delivers enamides.
T. Ghosh, S. Jana, J. Dash, Org. Lett., 2019, 21, 6690-6694.
A general, mild, and highly chemoselective method for transamidation of unactivated tertiary amides by a direct acyl N-C bond cleavage with non-nucleophilic amines is performed in the absence of transition metals and operates under unusually mild reaction conditions. A direct amidation of abundant alkyl esters affords amide bonds with exquisite selectivity by acyl C-O bond cleavage.
G. Li, C.-L. Ji, X. Hong, M. Szostak, J. Am. Chem. Soc., 2019, 141, 11161-11172.
A simple catalyst- and metal-free protocol enables a chemoselective transamidation of activated secondary amides in ethanol as solvent under mild conditions. A wide range of amines, amino acids, amino alcohols are tolerated in this methodology. The transamidation reaction was successfully extended to water as the medium as well.
R. Ramkumar, S. Chandrasekaran, Synthesis, 2019, 51, 921-932.
Nonplanar, electronically destabilized amides are powerful intermediates in organic synthesis. A highly selective method for transamidation of common secondary amides under mild, metal-free conditions relies on transient N-selective functionalization to weaken amidic resonance. This procedure accomplishes challenging transamidation of secondary amides under mild conditions.
Y. Liu, S. Shi, M. Achtenhagen, R. Liu, M. Szostak, Org. Lett., 2017, 19, 1614-1617.
A facile, highly chemoselective transamidation of N-Boc activated secondary amides proceeds under exceedingly mild conditions in the absence of any additives. Because this reaction is performed in the absence of metals, oxidants, or reductants, the reaction tolerates a large number of useful functionalities.
Md. M. Rahman, G. Li, M. Szostak, J. Org. Chem., 2019, 84, 12091-12100.
Formation of unstable but reactive acyl nitroso intermediates from Nα-protected hydroxamic acids in the presence of iodine and DMSO enables an efficient and straightforward coupling with an amino component to yield dipeptide esters.
M. Krishnamurthy, T. M. Vishwanatha, N. R. Panguluri, V. Panduranga, V. V. Sureshbabu, Synlett, 2015, 26, 2565-2569.
The reaction of N,N-dialkylformamide dimethyl acetal with primary amides produces N'-acyl-N,N-dialkylformamidines as intermediates. In the presence of certain Lewis acid additives efficient acyl transfer occurs, providing new and useful methods for amide exchange such as transamidation.
T. A. Dineen, M. A. Zajac, A. G. Myers, J. Am. Chem. Soc., 2006, 128, 16406-16409.