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Conclusions. In conclusion, we have developed a green version of organo- phosphorus-catalysed amide bond formation between unacti- vated aromatic carboxylic acids and amines. The commercially available pre-catalyst 3-methyl-1-phenyl-2-phospholene oxide 4 is reduced in situ by inexpensive and environmentally benign poly(methylhydrosiloxane) and bis( p-nitrophenyl) phosphate. With our newly developed method a wide variety of secondary and tertiary amides could be synthesised in very good to excel- lent yields. It is envisioned that organophosphorus catalysis will be a subject of extensive investigations in the upcoming years. Moreover, we believe that poly(methylhydrosiloxane) will find practical applications in several other common reactions in organic chemistry. Experimental A Radleys tube equipped with a magnetic stirbar was charged with carboxylic acid (0.5 mmol, 1.0 equiv.), phosphine oxide 4 (0.075 mmol or 0.125 mmol; 0.15 or 0.25 equiv.), and Published on 17 July 2017. Downloaded by Radboud University Nijmegen on 3/8/2019 8:23:31 AM. bis( p-nitrophenyl) phosphate (0.025 mmol, 0.05 equiv.). Subsequently toluene (2.5 mL, 0.2 M) was added, and to the formed suspension were added benzylamine (0.65 mmol, 1.3 equiv.), CCl4 (1.0 mmol, 2.0 equiv.), and poly(methyl- hydrosiloxane) (Mw 2450 Da, 0.12 mmol, 9 Si–H equiv.). The reaction was stirred at 110 °C for 20 hours. After cooling to room temperature, toluene was removed under reduced pressure and the crude product was resuspended in ethyl acetate (20 mL). The organic phase was washed with sat. aqueous NaHCO3 (2 × 20 mL), brine (1 × 20 mL), dried over Na2SO4, filtered, and evaporated. The crude product was puri- fied by silica column chromatography (ethyl acetate and n-heptane) to afford the desired amide. Conflict of interest There are no conflicts of interest to declare. Acknowledgements We thank Dr Xxxx Xxxxx for technical assistance with in situ VT 1H NMR and 31P NMR experiments. Notes and references 1 (a) X. X. xxx Xxxxxxxx, X. X. xxx Xxxxx and F. P. J. T. Rutjes, ChemSusChem, 2013, 6, 1615–1624; (b) X. Xxxxxxxxx and X. Xxxxx, Tetrahedron Lett., 2016, 57, 4443–4451. 2 (a) X. X. Xxxxxxx, X. X. XxXxxxxxx and X. XxXxxxxx-Xxxxx, Org. Lett., 2008, 10, 2589–2591; (b) X. Xxxx, X. Xxxxxxx, X. Xxxxxxx and X. Xxxxxx, Chem. Commun., 2014, 50, 7340–7343; (c) X. Xx, X. Xxxx, X. Xxxxx, X. Xxxxx and X. X. Xxxxxx, Tetrahedron, 2013, 69, 8769– 8776; (d) X. X. Xxxxxx, X. Xx, X. Xxxxxxxx, X. X. Xxxxx, X. Xxxxx and A. M. Xxxxxxx, X. Xxx. Chem., 2011, 76, 6749– 6767. 3 (a) X. Xxxx, X. X. Xxx, N. Y. Xxxxx, X. X. Xxx, X. X. Xx, X. X. Xxx and X. X. Xxxx, ACS Catal., 2016, 6, 4010– 4016; (b) X. X. Xxxxx, X. X. Xxxxxx, X. X. Xxxxxxx, X. X. Xxxxx, X. Xxxxxxx, X. X. Xxxxxxx and X. X. X’Xxxxx, Angew. Chem., Int. Ed., 2014, 53, 12907–12911;