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L. S. BOULOS ET AL.
reduced pressure. The residue was chromatographed on silica gel column to give two prod-
ucts: 2,2ꢁ-4,4ꢁ-di-tert-butyl-6,6ꢁ-[1,2-bis(diphenylphosphoryl)ethane-1,2-diyl-]bis(6-hyd-
roxycyclohexa-2,4-dien-1-one) (10) and ethane 1,2-diylbis(diphenylphosphane)dioxide
(8a).
When 1,2-bis(diphenylphosphino)ethane (1a) was boiled in dry THF or dry toluene
for more than 10 h, the same reagent 1a was isolated unchanged (mp and mixed mp).
2,2ꢀ-4,4ꢀ-Di-tert-butyl-6,6ꢀ-[1,2-bis(diphenylphosphoryl)ethane-1,2-
diyl-]bis(6-hydroxy-cyclohexa-2,4-dien-1-one) (10)
Eluent: petroleum ether/acetone◦(90/10, v/v). Product 10 was separated as colorless
crystals, yield 0.53 g (65%), mp 192 C. IR (KBr): ν = 1182 (P O), 1435 (P-Ph), 1677
(C O), 3262 (OH) cm−1. 1H NMR (500 MHz, CDCl3): δ = 1.25 (s, 18H, tert-butyl), 1.27 (s,
18H, tert-butyl), 2.41 (ddd, JHH = 6.8 Hz, 2JPH = 25.3 Hz, 3JPH = 11.0 Hz, 2H, Ph2P(O)CH-
CH-P(O)Ph2), 2.80 (s, 2H, OH, exchangeable with D2O), 6.59 (s, 2H, cyclohexadienone),
6.64 (s, 2H, cyclohexadienone), 7.46-7.71 (m, 20H, arom-H). 13C NMR (125 MHz, CDCl3):
δ = 21.8 (d, JPC = 130.0 Hz, C-P O), 30.0 (s, tert-butyl), 32.0 (s, tert-butyl), 34.3 (s, tert-
butyl), 35.0 (s, tert-butyl), 82.6 (d, 2JPC = 40.1 Hz, cyclic C-OH), 113.6 (arom-CH), 129.3
(arom-C), 131.0 (arom-C), 132.4 (arom-C), 135.0 (arom-C), 140.4 (arom-C), 141.8 (arom-
C), 144.8 (arom-C), 189.5 (C O). 31P NMR (CDCl3): δ = 36.1. MS (FAB+): m/z (%) = 871
(M+, 10), 670 (M+-(O PPh2), 25), 428 (Ph2P(O)CH-CH-P(O)Ph2, 55). Anal. Calcd. for
C54H64O6P2 (871.03): C, 74.46; H, 7.41; P, 7.11. Found: C, 74.41; H, 7.42; P, 7.12%.
Ethane 1,2-Diylbis(diphenylphosphane)dioxide (8a)
Eluent: petroleum ether/acetone (50/50, v/v). Product 8a was separated as colorless
crystals, yield 0.09 g (15%), mp 276 ◦C. IR (KBr): ν = 1183 (P O), 1437 (P-Ph) cm−1
.
1H NMR (500 MHz, CDCl3): δ = 2.41 (s, JPH = 6.8 Hz, 4H, Ph2P(O)CH2-CH2-P(O)Ph2),
7.36-7.63 (m, 20H, arom-H). 13C NMR (125 MHz, CDCl3): δ = 21.4 (C-P O), 128.7
(arom-C), 130.4 (arom-C), 131.8 (arom-C), 132.5 (arom-C). 31P NMR (CDCl3): δ = 33.2.
MS (EI): m/z (%) = 430 (M+, 60). Anal. Calcd. for C26H24O2P2 (430.42): C, 72.55; H,
5.62; P, 14.39. Found: C, 72.50; H, 5.63; P, 14.38.
Reaction of 1,2-Bis(diphenylphosphino)ethane (1a) with
3,4,5,6-Tetrabromo-o-benzo-quinone (3a)
3,4,5,6-Tetrabromo-o-benzoquinone (3a, 0.84 g, 2 mmol) and 1,2-bis(diphenylphos-
phino)-ethane (1a, 0.39 g, 1 mmol) were stirred in 30 mL dry THF. The reaction was
almost completed at r.t.; the course of the reaction was monitored by TLC. The volatile
materials were evaporated under reduced pressure. The residue was chromatographed on
silica gel column to give the 6,6ꢁ-[1,2-bis(diphenylphosphoryl)ethane-1,2-diyl]bis(2,3,4,5-
tetrabromo-6-hydroxycyclohexa-2,4-dien-1-one) (12) and compound 8a.
6,6ꢀ-[1,2-Bis(diphenylphosphoryl)ethane-1,2-diyl]bis(2,3,4,5-
tetrabromo-6-hydroxycyclo-hexa-2,4-dien-1-one) (12)
Eluent: petroleum ether/ethyl acetate (75/25, v/v). Product 12 was separated as col-
orless crystals, yield 0.79 g (65%), mp 130 ◦C. IR (KBr): ν = 1185 (P O), 1435 (P-Ph),
1677 (C O), 3252 (OH) cm−1. 1H NMR (500 MHz, CDCl3): δ = 2.35 (ddd, JHH = 5.6 Hz,