Quinolin-8-yl Formate: A New Option for Small-Scale Carbonylation Reactions in Microwave Reactors

Abstract

A convenient procedure for conducting small-scale carbonylations of aryl or benzyl halides in a microwave reactor by using quinolin-8-yl formate is described. The resulting 8-acyloxyquinolines were shown to be more reactive than phenyl esters in acyl-transfer reactions, and their utility for the production of esters and amides was demonstrated.

Key words

carbonylation - microwave heating - palladium catalysis - carbon monoxide surrogates - benzylic halides - aryl halides

• References and Notes

• 1 New addresses: J. Richardson, Sai Life Sciences Limited, Basement A, Block 33, Alderley Park, Macclesfield, SK10 4TG, UK. C. Maddocks, Department of Chemistry, University of York, Heslington­, York, YO10 5DD, UK.
• 2 Schoenberg A, Bartoletti I, Heck RF. J. Org. Chem. 1974; 39: 3318
• 3 Schoenberg A, Heck RF. J. Org. Chem. 1974; 39: 3327
• 4 Brennführer A, Neumann H, Beller M. Angew. Chem. Int. Ed. 2009; 48: 4114
• 5 Peng J.-B, Geng H.-Q, Wu X.-F. Chem 2019; 5: 526
• 6a Carpentier J.-F, Castanet Y, Brocard J, Mortreux A, Petit F. Tetrahedron Lett. 1991; 32: 4705
• 6b Simonato J.-P, Walter T, Métivier P. J. Mol. Catal. A: Chem. 2001; 171: 91
• 6c Kaiser N.-FK, Hallberg A, Larhed M. J. Comb. Chem. 2002; 4: 109
• 6d Morimoto T, Fuji K, Tsutsumi K, Kakiuchi K. J. Am. Chem. Soc. 2002; 124: 3806
• 6e Morimoto T, Fujioka M, Fuji K, Tsutsumi K, Kakiuchi K. Chem. Lett. 2003; 32: 154
• 6f Hermange P, Lindhardt AT, Taaning RH, Bjerglund K, Lupp D, Skrydstrup T. J. Am. Chem. Soc. 2011; 133: 6061
• 6g Friis SD, Taaning RH, Lindhardt AT, Skrystrup T. J. Am. Chem. Soc. 2011; 133: 18114
• 6h Nakaya R, Yorimitsu H, Oshima K. Chem. Lett. 2011; 40: 904
• 6i Brancour C, Fukuyama T, Mukai Y, Skrydstrup T, Ryu I. Org. Lett. 2013; 15: 2794
• 6j Ueda T, Konishi H, Manabe K. Angew. Chem. Int. Ed. 2013; 52: 8611
• 6k Natte K, Dumrath A, Neumann H, Beller M. Angew. Chem. Int. Ed. 2014; 53: 10090
• 6l Qi X, Li C.-L, Jiang L.-B, Zhang W.-Q, Wu X.-F. Catal. Sci. Technol. 2016; 6: 3099
• 6m Jiang L.-B, Qi X, Wu X.-F. Tetrahedron Lett. 2016; 57: 3368
• 6n Wu F.-P, Peng J.-B, Meng L.-S, Qi X, Wu X.-F. ChemCatChem 2017; 9: 3121
• 6o Peng J.-B, Qi X, Wu X.-F. Synlett 2017; 28: 175
• 7 Fujihara T, Hosoki T, Katafuchi Y, Iwai T, Terao J, Tsuji Y. Chem. Commun. 2012; 48: 8012
• 8 Ueda T, Konishi H, Manabe K. Org. Lett. 2012; 14: 3100
• 9 Godfrey AG, Masquelin T, Hemmerle H. Drug Discovery Today 2013; 18: 795
• 10 Ueda T, Konishi H, Manabe K. Org. Lett. 2012; 14: 5370
• 11 N-Hydroxysuccinimidyl formate has also been reported to act as a solid CO surrogate that yields active esters, but it liberates CO at room temperature when treated with Et3N; see Supporting Information of: Barré A, Tînţaş M.-L, Alix F, Gembus V, Papamicaël C, Levacher V. J. Org. Chem. 2015; 80: 6537
• 12 Suggs JW, Pearson GD. N. Tetrahedron Lett. 1980; 21: 3853
• 13 Ho T.-L. Synth. Commun. 1977; 7: 393
• 14 Martinelli JR, Watson DA, Freckmann DM. M, Barder TE, Buchwald SL. J. Org. Chem. 2008; 73: 7102
• 15a For a report on the second-generation palladacycle family, see: Kinzel T, Zhang Y, Buchwald SL. J. Am. Chem. Soc. 2010; 132: 14073
• 15b For a report on the use of the fourth-generation Xantphos palladacycle in carbonylations, see: Friis SD, Skrydstrup T, Buchwald SL. Org. Lett. 2014; 16: 4296
• 16 Barnard CF. J. Org. Process Res. Dev. 2008; 12: 566
• 17 It is crucial that reactions are always conducted at or above the minimum working volume for the tube size chosen to avoid overheating and possible vessel failure due to incorrect temperature measurements in the microwave.
• 18 When using high loadings of Xantphos-Pd-G2, small amounts of 8-quinolyl benzoate derived from phenyl transfer from the ligand were sometime seen. For an earlier report of phenyl transfer from Xantphos in carbonylations, see reference 11.
• 19 Quinolin-8-yl 4-Methoxybenzoate (3a); Typical Procedure 4-Bromoanisole (378 mg, 2.02 mmol), quinolin-8-yl formate (2, 383 mg, 2.21 mmol, 1.1 equiv), and Xantphos-Pd-G2 (36 mg, 0.040 mmol, 2.0 mol%) were added to a 2–5 mL Biotage microwave tube (Part no. 351521) under N₂. Toluene (4.0 mL) and Et₃N (0.56 mL, 4.0 mmol, 2.0 equiv) were added sequentially, and the tube was capped and heated in a Biotage Initiator microwave at 120 °C for 60 min. When heating was complete and the microwave cavity had been opened, significant solid formation was observed in the tube. The contents of the tube were transferred to a separatory funnel with CH₂Cl₂ (30 mL), and the resulting mixture was washed with H₂O (20 mL). The organic layer was separated and injected directly onto a silica column (80 g). The product was eluted with a 0–10% gradient of MeCN in CH₂Cl₂ then dried at 35 °C under a vacuum to give an off-white solid; yield: 496 mg (88%). ¹H NMR (400 MHz, CDCl₃): δ = 8.88 (dd, J = 4.3, 1.6 Hz, 1 H), 8.29 (d, J = 9.0 Hz, 2 H), 8.18 (dd, J = 8.4, 1.6 Hz, 1 H), 7.74 (dd, J = 7.4, 2.2 Hz, 1 H), 7.52–7.59 (m, 2 H), 7.41 (dd, J = 8.4, 4.3 Hz, 1 H), 7.00 (d, J = 9.0 Hz, 2 H), 3.89 (s, 3 H). ¹³C NMR (101 MHz, CDCl₃): δ = 165.4, 164.1, 150.8, 148.0, 141.8, 136.2, 132.9, 129.8, 126.5, 126.1, 122.1, 121.9, 121.9, 114.1, 55.7.
• 20 A conversion of 8-acyloxyquinolines into ketones by using organoaluminum reagents has been reported; see: Tolstikov GA, Valitov FKh, Kuchin AV. Zh. Obshch. Khim. 1982; 52: 1328
• 21 For an early example of the conversion of a morpholinoamide into a ketone, see: Pettit GR, Baumann MF, Rangammal KN. J. Med. Chem. 1962; 5: 800