Michael addition catalyzed by difluorotris(pentafluoroethyl)phosphorane

Tris(pentafluoroethyl)difluorophosphorane: A Versatile Fluoride Acceptor for Transition Metal Chemistry

“…[26b, 32] Due to its high Lewis acidity the phosphorane( C 2 F 5 ) 3 PF 2 has been used as ac atalyst, for example, in Diels-Alder reactions [33] and Michael additions. [34] It was shown that (C 2 F 5 ) 3 PF 2 enhances the Brønsted acidity of acetonitrile, which, in the presence of Et 3 N, enabledt he synthesis of [Et 3 NH][(C 2 F 5 ) 3 PF 2 (CH 2 CN)] with deprotonated acetonitrile CH 2 CN À coordinated to the phosphorus center. [35] As noted above, the FAP anion [(C 2 F 5 ) 3 PF 3 ] À can be obtained from (C 2 F 5 ) 3 PF 2 and as uitable fluorides ource.…”

Tris(pentafluoroethyl)difluorophosphorane and N‐Heterocyclic Carbenes: Adduct Formation and Frustrated Lewis Pair Reactivity

“…The CF 2 groups were detected at À 111.9, À 114.5 and À 116.2 ppm, respectively. From the 19 F{ 31 P} NMR spectrum it is evident that the doublet splitting of the multiplets at À 116.2 ppm with a coupling constant of 299 Hz does not arise from coupling with phosphorus. However, the same coupling constant was observed for the doublet of doublets of doublets at À 111.9 ppm, which implies FÀ F coupling.…”

“…[29] In contact with water or moisture it undergoes slow hydrolysis. It was applied as Lewis acidic catalyst in Diels-Alder reactions, [30] and Michael additions [31] or in transfer hydrogenations. [32] As a strong Lewis acid, PF 2 (C 2 F 5 ) 3 reacts with nucleophiles such as H À , [33] HO À , CH 3 C(=O)O À , [34] F À , [23,28] or Cl À .…”

“…CN, 298 K): δ = 8.20 (m, 1H, PÀ CÀ CH), 7.63 (br, 1H, NÀ CHÀ N), 1.73 (t, 9H, TS J F-H = 2.4 Hz, PÀ CÀ NÀ C(CH 3 ) 3 ), 1.56 (s, 9H, CHÀ NÀ C-(CH 3 ) 3 ;13 C{ 1 H} NMR (100.7 MHz, CD 3 CN, 298 K): δ = 147.4 (PÀ CÀ N), 134.9 (PÀ CÀ CH), 127.0 (NÀ CHÀ N), 67.6 (PÀ CÀ NÀ C(CH 3 ) 3 ), 60.3 (CHÀ NÀ C(CH 3 ) 3 ),31.6 (PÀ CÀ NÀ C(CH 3 ) 3 ),29.1 (CHÀ NÀ C(CH 3 ) 3 );19 F NMR (376.8 MHz, CD 3 CN, 298 K): δ = À 79.0 (m, 6F, CF 3 ), À 80.3 (m, 3F, CF 3 ), À 88.1 (d, d, m, 1F, 1 J P-F � 860 Hz, 2 J F-F = 104 Hz, PF) overlap with À 90.3 (d, d, m, 1F, J P-F � 880 Hz, J F-F = 104 Hz, PF), À 101.0 (d, d, m, 2F, 2 J F-F = Hz, 2 J P-F = 113 Hz, CF ), À 115.3 (d, m, 2F, 2 J P-F = 100 Hz, CF 2 ), À 119.0 (d, m, 2F, 2 J F-F = 292 Hz, CF 2 );31 P NMR (202.4 MHz, CD 3 CN, 298 K): δ = À 146.3 (d, d, t, t, 1 J P-F � 880 Hz, 1 J P-F � 860 Hz, 2 J P-F = 113 Hz, 2 J P-F = 100 Hz); IR ([cm À 1 ]): 3208 (w), 3196 (w), 2995 (w), 2946 (vw), 1674 (vw), 1564 (w), 1507 (vw), 1470 (vw), 1411 (vw), 1396 (vw), 1381 (w), 1295 (m), 1266 (w), 1227 (s), 1208 (s), 1177 (vs), 1139 (s), 1124 (s), 1114 (s), 1089 (s), 1063 (m), 1004 (w), 950 (m), 857 (w), 819 (m), 811 (m), 739 (m), 700 (w), 654 (w), 642 (w), 621 (m), 598 (m), 566 (vs), 535 (m), 495 (w), 453 (w), 432 (w); elemental analysis calcd (%) for C 17 H 20 F 17 N 2 P: C 33.68, H 3.33, N, 4.62; found: C 33.85, H 3.11, N 4.92. [tBuMeImÀ H][MeImÀ PF 2 (C 2 F 5 ) 3 ] (4 m) A solution of tBuMeIm (1 m) (681 mg, 4.93 mmol) in Et 2 O (15 mL) was cooled to 0°C and added to a solution of PF 2 (C 2 F 5 ) 3 (1.05 g, 2.46 mmol) in Et 2 O (5 mL) at 0°C via cannula.…”

“…F-F = 96 Hz, PF), À 111.9 (d, d, q, 2F, 2 J F-F = 295 Hz, 2 J P-F = 86 Hz, F-F = 8.3 Hz, CF 2 ), À 115.7 (d, m, 2F, 2 J P-F = 100 Hz, CF 2 ), À 118.6 (d, m, 2F, 2 J F-F = 295 Hz, CF 2 );31 P NMR (202.4 MHz, CD 3 CN, 298 K): δ = À 149.1 (m); IR ([cm À 1 ]): 3178 (w), 3159 (w), 2999 (w), 2239 (w), 1593 (w), 1562 (w), 1540 (m), 1469 (w), 1430 (w), 1409 (w), 1380 (m), 1295 (m), 1202 (vs), 1189 (vs), 1167 (vs), 1129 (vs), 1118 (vs), 1073 (s), 1056 (m), 946 (s), 844 (m), 831 (m), 797 (vs), 737 (m), 680 (s), 653 (m), 639 (w), 597 (m), 555 (vs), 522 (vs), 431 (m); ESI-MS (Orbitrap) m/z [M…”