Organic Letters
Letter
Biomol. Chem. 2006, 4, 2337−2347. (c) Pattabiraman, V. R.; Bode, J. W.
Rethinking amide bond synthesis. Nature 2011, 480, 471−479.
(d) Roughley, S. D.; Jordan, A. M. The medicinal chemist’s toolbox:
an analysis of reactions used in the pursuit of drug candidates. J. Med.
Chem. 2011, 54, 3451−3479. (e) de Figueiredo, R. M.; Suppo, J.-S.;
Campagne, J.-M. Nonclassical routes for amide bond formation. Chem.
Rev. 2016, 116, 12029−12122.
(2) (a) Allen, C. L.; Williams, J. M. Metal-catalysed approaches to
amide bond formation. Chem. Soc. Rev. 2011, 40, 3405−3415.
(b) Lundberg, H.; Tinnis, F.; Selander, N.; Adolfsson, H. Catalytic
amide formation from non-activated carboxylic acids and amines.
Chem. Soc. Rev. 2014, 43, 2714−2742. (c) Takise, R.; Muto, K.;
Yamaguchi, J. Cross-coupling of aromatic esters and amides. Chem. Soc.
Rev. 2017, 46, 5864−5888.
amidation) under the same reaction conditions. Chem. Commun. 2017,
53, 10584−10587.
(15) Li, G.; Szostak, M. Highly selective transition-metal-free
transamidation of amides and amidation of esters at room temperature.
Nat. Commun. 2018, 9, 4165.
(16) Ben Halima, T.; Vandavasi, J. K.; Shkoor, M.; Newman, S. G. A
cross-coupling approach to amide bond formation from esters. ACS
Catal. 2017, 7, 2176−2180.
(17) Ben Halima, T.; Masson-Makdissi, J.; Newman, S. G. Nickel-
catalyzed amide bond formation from methyl esters. Angew. Chem., Int.
Ed. 2018, 57, 12925−12929.
(18) Kadam, H. K.; Tilve, S. G. Advancement in methodologies for
reduction of nitroarenes. RSC Adv. 2015, 5, 83391−83407.
(19) (a) Cheung, C. W.; Ploeger, M. L.; Hu, X. Direct amidation of
esters with nitroarenes. Nat. Commun. 2017, 8, 14878. (b) Cheung, C.
W.; Ploeger, M. L.; Hu, X. Nickel-catalyzed reductive transamidation of
secondary amides with nitroarenes. ACS Catal. 2017, 7, 7092−7096.
(20) (a) Cheung, C. W.; Ploeger, M. L.; Hu, X. Amide synthesis via
nickel-catalysed reductive aminocarbonylation of aryl halides with
nitroarenes. Chem. Sci. 2018, 9, 655−659. (b) Cheung, C. W.; Ma, J.-A.;
Hu, X. Manganese-mediated reductive transamidation of tertiary
amides with nitroarenes. J. Am. Chem. Soc. 2018, 140, 6789−6792.
(c) Cheung, C. W.; Shen, N.; Wang, S.-P.; Ullah, A.; Hu, X.; Ma, J.-A.
Manganese-mediated reductive amidation of esters with nitroarenes.
(3) Shi, S.; Nolan, S. P.; Szostak, M. Well-Defined Palladium(II)−
NHC Precatalysts for Cross-Coupling Reactions of Amides and Esters
by Selective N−C/O−C Cleavage. Acc. Chem. Res. 2018, 51, 2589−
2599.
(4) (a) Basha, A.; Lipton, M.; Weinreb, S. M. A mild, general method
for conversion of esters to amides. Tetrahedron Lett. 1977, 18, 4171−
4172. (b) Wang, W.-B.; Roskamp, E. J. Tin(II) amides: new reagents for
the conversion of esters to amides. J. Org. Chem. 1992, 57, 6101−6103.
(c) Kurosawa, W.; Kan, T.; Fukuyama, T. Stereocontrolled total
synthesis of (−)-ephedradine A (orantine). J. Am. Chem. Soc. 2003, 125,
8112−8113. (d) Ohshima, T.; Hayashi, Y.; Agura, K.; Fujii, Y.;
Yoshiyama, A.; Mashima, K. Sodium methoxide: a simple but highly
efficient catalyst for the direct amidation of esters. Chem. Commun.
2012, 48, 5434−5436.
(5) Gnanaprakasam, B.; Milstein, D. Synthesis of amides from esters
and amines with liberation of H2 under neutral conditions. J. Am. Chem.
Soc. 2011, 133, 1682−1685.
(6) Kumar, A.; Espinosa-Jalapa, N. A.; Leitus, G.; Diskin-Posner, Y.;
Avram, L.; Milstein, D. Direct synthesis of amides by dehydrogenative
coupling of amines with either alcohols or esters: manganese pincer
complex as catalyst. Angew. Chem., Int. Ed. 2017, 56, 14992−14996.
(7) Han, C.; Lee, J. P.; Lobkovsky, E.; Porco, J. A., Jr. Catalytic ester-
amide exchange using group (IV) metal alkoxide-activator complexes. J.
Am. Chem. Soc. 2005, 127, 10039−10044.
(8) Hie, L.; Fine Nathel, N. F.; Hong, X.; Yang, Y.-F.; Houk, K. N.;
Garg, N. K. Nickel-catalyzed activation of acyl C−O Bonds of methyl
esters. Angew. Chem., Int. Ed. 2016, 55, 2810−2814.
(9) Baker, E. L.; Yamano, M. M.; Zhou, Y. J.; Anthony, S. M.; Garg, N.
K. A two-step approach to achieve secondary amide transamidation
enabled by nickel catalysis. Nat. Commun. 2016, 7, 11554.
(10) Dander, J. E.; Baker, E. L.; Garg, N. K. Nickel-catalyzed
transamidation of aliphatic amide derivatives. Chem. Sci. 2017, 8,
6433−6438.
(11) Selected reviews of catalytic activation of C−O bonds: (a) Rosen,
B. M.; Quasdorf, K. W.; Wilson, D. A.; Zhang, N.; Resmerita, A.-M.;
Garg, N. K.; Percec, V. Nickel-catalyzed cross-couplings involving
carbon−oxygen bonds. Chem. Rev. 2011, 111, 1346−1416. (b) Tobisu,
M.; Chatani, N. Cross-Couplings Using Aryl Ethers via C−O Bond
Activation Enabled by Nickel Catalysts. Acc. Chem. Res. 2015, 48,
1717−1726. (c) Yu, D.-G.; Li, B.-J.; Shi, Z.-J. Exploration of New C−O
Electrophiles in Cross-Coupling Reactions. Acc. Chem. Res. 2010, 43,
1486−1495. (d) Cornella, J.; Zarate, C.; Martin, R. Metal-catalyzed
activation of ethers via C−O bond cleavage: a new strategy for
molecular diversity. Chem. Soc. Rev. 2014, 43, 8081−8097.
(e) Yamaguchi, J.; Muto, K.; Itami, K. Recent Progress in Nickel-
Catalyzed Biaryl Coupling. Eur. J. Org. Chem. 2013, 2013, 19−30.
(12) Liu, Y.; Shi, S.; Achtenhagen, M.; Liu, R.; Szostak, M. Metal-free
transamidation of secondary amides via selective N−C cleavage under
mild conditions. Org. Lett. 2017, 19, 1614−1617.
(21) (a) Zeng, X.; Cong, X. Chromium-catalyzed transformations
with Grignard reagents−new opportunities for cross-coupling reac-
tions. Org. Chem. Front. 2015, 2, 69−72. (b) Furstner, A. Carbon−
̈
carbon bond formations involving organochromium(III) reagents.
Chem. Rev. 1999, 99, 991−1046.
(22) Selected recent examples of Cr catalysis: (a) Yan, J.; Yoshikai, N.
Phenanthrene synthesis via chromium-catalyzed Annulation of 2-biaryl
Grignard reagents and alkynes. Org. Lett. 2017, 19, 6630−6633.
(b) Yan, J.; Yoshikai, N. Chromium-catalyzed migratory arylmagnesia-
tion of unactivated alkynes. Org. Chem. Front. 2017, 4, 1972−1975.
(c) Murakami, K.; Ohmiya, H.; Yorimitsu, H.; Oshima, K. Chromium-
catalyzed arylmagnesiation of alkynes. Org. Lett. 2007, 9, 1569−1571.
(d) Steib, A. K.; Kuzmina, O. M.; Fernandez, S.; Flubacher, D.;
Knochel, P. Efficient chromium(II)-catalyzed cross-coupling reactions
between Csp2 centers. J. Am. Chem. Soc. 2013, 135, 15346−15349.
(e) Cong, X.; Tang, H.; Zeng, X. Regio- and chemoselective Kumada−
Tamao−Corriu reaction of aryl alkyl ethers catalyzed by chromium
under mild conditions. J. Am. Chem. Soc. 2015, 137, 14367−14372.
(f) Cong, X.; Fan, F.; Ma, P.; Luo, M.; Chen, H.; Zeng, X. Low-valent,
high-spin chromium-catalyzed cleavage of aromatic carbon−nitrogen
bonds at room temperature: a combined experimental and theoretical
study. J. Am. Chem. Soc. 2017, 139, 15182−15190. (g) Chen, C.; Liu, P.;
Luo, M.; Zeng, X. Kumada arylation of secondary amides enabled by
chromium catalysis for unsymmetric ketone synthesis under mild
conditions. ACS Catal. 2018, 8, 5864−5868. (h) Tang, J.; Liu, P.; Zeng,
X. N-Heterocyclic carbene−chromium-catalyzed alkylative cross-
coupling of benzamide derivatives with aliphatic bromides. Chem.
Commun. 2018, 54, 9325−9328.
(23) Docherty, J. H.; Peng, J.; Dominey, A. P.; Thomas, S. P.
Activation and discovery of earth-abundant metal catalysts using
sodium tert-butoxide. Nat. Chem. 2017, 9, 595−600.
(24) Mock, M. T.; Chen, S.; O’Hagan, M.; Rousseau, R.; Dougherty,
W. G.; Kassel, W. S.; Bullock, R. M. Dinitrogen reduction by a
chromium(0) complex supported by a 16-membered phosphorus
macrocycle. J. Am. Chem. Soc. 2013, 135, 11493−11496.
(25) Skobelev, I. Y.; Panchenko, V. N.; Lyakin, O. Y.; Bryliakov, K. P.;
Zakharov, V. A.; Talsi, E. P. Organometallics 2010, 29, 2943−2950.
(13) Meng, G.; Lei, P.; Szostak, M. A general method for two-step
transamidation of secondary amides using commercially available, air-
and moisture-stable palladium/NHC (N-heterocyclic carbene) com-
plexes. Org. Lett. 2017, 19, 2158−2161.
(14) Shi, S.; Szostak, M. Pd−PEPPSI: a general Pd−NHC precatalyst
for Buchwald−Hartwig cross-coupling of esters and amides (trans-
E
Org. Lett. XXXX, XXX, XXX−XXX