TETRAOXADIPHOSPHADIBOROCANE-2,6-DIONES
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60–70 ꢀC with stirring for 40–50 h. When thin-layer chromatographic (TLC) analysis
indicated completion of the reaction, the reaction mixture was filtered. The filtrate
was concentrated under reduced pressure, washed with water, and extracted
with diethyl ether (3 ꢁ 20 mL). The combined organic layer was concentrated in vac-
uum, and the residue was washed with hexane repeatedly to remove any residual
impurities and recrystallized from diethyl ether to yield pure 2,6-diaryl=alkyl-4,8-
diphenyl-1,3,5,7,2k5,6k5,4,8-tetraoxadiphosphadiborocane-2,6-diones (3a–f).
2,6-Dimethyl-4,8-diphenyl-1,3,5,7,2k5,6k5,4,8-tetraoxadiphosphadi-
borocane-2,6-dione (3a). Molecular formula (MF): C14H16B2O6P2; yield: 49%;
mp: 159–161 ꢀC. Anal. calcd. (%): C, 46.22; H, 4.43. Found: C, 46.15; H, 4.35, IR
(KBr) (nmax cmꢂ1): 1217 (P O), 1094 (P-O); 31P NMR (121 MHz, CDCl3): d 4.13;
=
11B-NMR (64 MHz, CDCl3): d 22.82; H-NMR (400 MHz, CDCl3): d 7.62–7.16
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(10H, m, Ar-H), 2.29–2.20 (6H, br, P-CH); 13C NMR (75 MHz, CDCl3): d 135.63,
132.68, 127.98, 23.08; LCMS: m=z (%): 362 (29), [M ꢂ Hþ], 360 (47), 314 (32), 270
(44), 226 (100), 156 (17), 112 (88).
2,6-Diethyl-4,8-diphenyl-1,3,5,7,2k5,6k5,4,8-tetraoxadiphospha-
diborocane-2,6-dione (3b). MF: C16H20B2O6P2; yield: 63%; mp: 228–230 ꢀC.
Anal. calcd. (%): C, 49.04; H, 5.14. Found: C, 48.99; H, 5.12, IR (KBr) (nmax cmꢂ1):
1222 (P O), 1027 (P-O); 31P NMR (121 MHz, CDCl3): d 6.87; 11B NMR (64 MHz,
=
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CDCl3): d 22.78; H NMR (400 MHz, CDCl3): d 7.75–7.17 (10H, m, Ar-H), 2.97
(4H, br, P-CH), 1.07 (6H, br, P-CH-CH); 13C NMR (75 MHz, CDCl3): d 135.52,
128.02, 127.95, 40.02, 22.16; LCMS: m=z (%): 391 (23) [Mþ], 390 [M ꢂ Hþ] (47), 344
(53), 298 (50), 265 (59), 229 (100), 183 (61), 160 (51).
4,8-Diphenyl-2,6-dipropyl-1,3,5,7,2k5,6k5,4,8-tetraoxadiphosphadi-
borocane-2,6-dione (3c). MF: C18H24B2O6P2; yield: 71%; mp: 241–243 ꢀC. Anal.
calcd. (%): C, 51.48; H, 5.76. Found: C, 51.43; H, 5.81, IR (KBr) (nmax cmꢂ1): 1218
(P O), 1098 (P-O); 31P NMR (121 MHz, DMSO-d6): d 9.52; 11B NMR (64 MHz,
=
DMSO-d6): d 22.89; 1H NMR (400 MHz, DMSO-d6): d 7.65, 7.36 (10H, brs,
Ar-H), 3.16 (4H, br, P-CH), 1.35 (4H, br, P-C-CH), 0.93 (6H, br, P-C-C-CH); 13C
NMR (75 MHz, DMSO-d6): 129.88 (C-2, C-6), 129.18 (C-3, C-5), 128.18 (C-4),
49.30 (C-10), 20.55 (C-20), 14.18 (C-30); LCMS: m=z (%): 419 (47) [Mþ], 396 (25),
354 (15), 295 (57), 242 (100), 219 (15).
2,4,6,8-Tetraphenyl-1,3,5,7,2k5,6k5,4,8-tetraoxadiphosphadiboro-cane-
2,6-dione (3d). MF: C24H20B2O6P2; yield: 59%; mp: 190–192 ꢀC. Anal. calcd. (%):
C, 59.07; H, 4.13. Found: C, 59.12; H, 4.21, IR (KBr) (nmax cmꢂ1): 1216 (P O), 1092
=
(P-O); 31P NMR (121 MHz, DMSO-d6): d 4.91; 11B NMR (64 MHz, DMSO-d6): d
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24.95; H NMR (400 MHz, DMSO-d6): d 7.65–6.84 (20H, br, Ar-H); 13C NMR
(75 MHz, CDCl3): d 137.73, 134.88, 130.48, 130.26, 124.82, 122.75; LCMS: m=z
(%): 487 (89) [Mþ], 473 (76), 441 (64), 419 (68), 396 (62), 373 (100).
2,6-Di(2-chlorophenyl)-4,8-diphenyl-1,3,5,7,2k5,6k5,4,8-tetraoxadiphos-
phadi-borocane-2,6-dione (3e). MF: C24H18B2Cl2O6P2; yield: 64%; mp:
218–220 ꢀC. Anal. calcd. (%): C, 51.76; H, 3.26. Found: C, 51.72; H, 3.31, IR
(KBr) (nmax cmꢂ1): 1216 (P O), 1097 (P-O); 31P NMR (121 MHz, CDCl3): d 6.63;
=
11B NMR (64 MHz, CDCl3): d 23.01; H NMR (400 MHz, CDCl3): d 8.04–7.30
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