Formylation, synthesis of benzaldehydes
A ligandless palladium-catalyzed reductive carbonylation of aryl iodides for the synthesis of aromatic aldehydes proceeded effectively even under ambient temperature and pressure.
W. Han, B. Liu, J. Chen, Q. Zhou, Synlett, 2017, 28, 835-840.
A palladium-catalyzed formylation of aryl halides with isocyanide in the presence of Et3SiH provides important aldehydes in good yield. This reaction offers mild conditions, convenient operation, low toxicity, and wide functional group tolerance.
X. Jiang, J.-M. Wang, Y. Zhang, Z. Chen, Y.-M. Zhu, S.-J. Ji, Org. Lett., 2014, 16, 3492-3495.
A palladium-catalyzed reductive carbonylation enables a facile and practical synthesis of aromatic aldehydes from aryl iodides and HCOOH. HCOOH serves not only as convenient and environmental-friendly C1 source but also as the reviving agent in the reductive elimination process of a Pd-catalyst.
G. Sun, X. Lv, M. Lei, L. Hu, Org. Lett., 2017, 19, 4235-4238.
O-Aryl N-isopropylcarbamates, conveniently prepared from phenols and isopropyl isocyanate, are subjected to an efficient ortho-lithiation protocol to afford the corresponding salicylaldehydes in a one-pot operation in high yields.
M. Kauch, D. Hoppe, Synthesis, 2006, 1575-1577.
Reaction of nitroarenes with tris(benzotriazol-1-yl)methyl anion followed by treatment with zinc bromide and hydrochloric acid yielded the corresponding p-nitroarylaldehydes in good to excellent yields.
A. R. Katritzky, L. Xie, Tetrahedron Lett., 1996, 37, 347-350.
An efficient iron-catalyzed C3-selective formylation of free or N-substituted provides 3-formylindoles in good yields in fairly short reaction times in the presence of formaldehyde and aqueous ammonia, with air as the oxidant. Moreover, this catalytic formylation of indoles can be applied to gram-scale syntheses.
Q.-D. Wang, B. Zhou, J.-M. Yang, D. Fang, J. Ren, B.-B. Zeng, Synlett, 2017, 28, 2670-2674.
Eosin Y catalyzes a visible-light-mediated C-3 formylation of indole in the presence of tetramethylethylenediamine as a carbon source and air as an oxidant under mild conditions. This protocol tolerates a broad range of functional groups and provides 3-formylated indoles with good yields.
Y. Zhao, H. Li, S. Yin, Y. Wu, G. Ni, Synlett, 2022, 33, 659-663.