J Chem Crystallogr (2009) 39:337–347
339
toluene solution afforded diphenyl tritylphosphine-borane as
colorless needles. Isolated yield: 14% Mp: 146–150 °C, 1H
NMR (300 MHz, CDCl3) d 7.32 (t, 2H, ArH, 1J = 7.3 Hz),
7.24–7.19 (m, 5H, ArH), 7.15–7.14 (m, 12H, ArH), 7.10 (d,
and after evaporation of the solvent in vacuo, the residue
was washed several times with EtOAc and the precipitate
vacuum-filtered, giving 4 as a white powder. Isolated yield:
98%. Single crystals obtained from rt evaporation of a
1
1
1H, ArH, J = 2.6), 7.07–7.06 (m, 1H, ArH), 6.99 (t, 4H,
1
toluene/CH2Cl2/MeOH (5:1:1) Mp: 282–284 °C H NMR
(300 MHz, CDCl3) d 7.36–7.33 (m, 5H, ArH), 7.28–7.26
(m, 8H, ArH), 7.18–7.11 (m, 3H, ArH), 7.09–7.04 (m, 5H,
ArH, J = 8.8 Hz) 13C NMR (300 MHz, CDCl3) d 69.6,
125.3, 126.4, 126.5, 126.8, 127.0, 127.3, 127.5, 127.9, 128.4,
128.5, 129.9. 130.95, 131.0, 133.8, 133.9, 140.7, 142.9, 11
B
ArH). 13C NMR (75.45 MHz, CDCl3) d 63.92 (d, JPC
=
1
NMR (28.88 MHz, CDCl3) d –32.4 31P NMR (300 MHz,
1
94 Hz), 127.0, 127.6 (d, JPC = 13 Hz), 127.9, 131.4 (d,
9JPCCC = 6 Hz), 131.8, 133.5, 133.8 (d, JPCC = 9 Hz),
CDCl3) d 39.6, IR (nujol mull, cm-1) 3162, 2360, 1154.
2
141.3 31P NMR (121.47 MHz, CDCl3) d 45.5 (s), IR (KBr,
cm-1) 1164 (P=O), 956 (P–OH), HRMS (ES) calcd. for
C25H21O2P, (M–H) 383.1201, found 383.1212.
Synthesis of 3, Dimethyl Tritylphosphine-Borane
Procedure PCl3 (15.5 mL, 177.4 mmol) was added slowly
to the trityl H-phosphinic acid (5.5 g, 17.7 mmol) previ-
ously placed in a flask under N2 atmosphere, at rt. The
reaction mixture was stirred at rt for 1 h, then at reflux for
2 h. After cooling down to rt, the excess of PCl3 was
evaporated in vacuo, affording the tritylphosphonous
dichloride as a fluffy solid. The tritylphosphonous dichlo-
ride (1.7 g, 5 mmol) was dissolved in distilled THF
(16 mL) and the solution placed at -78 °C. CH3MgCl
(C = 3.0 M solution in THF, 6.7 mL, 20 mmol) was
added dropwise via syringe and the reaction mixture stirred
at rt for 12 h. Then, BH3.Me2S (C = 2.0 M in solution in
THF, 10 mL, 20 mmol) was added at rt and the mixture
stirred for 4 h. The reaction was quenched by addition of
deionized water at 0 °C. The aqueous layer was extracted
with EtOAc (39) and the combined organic extracts were
washed with brine (19), dried over MgSO4. After filtration
and evaporation, the residue was purified by column
chromatography on silica gel (100% toluene), affording 3
as a white powder. Isolated yield: 15%. Crystals suitable
for X-ray diffraction were obtained by rt evaporation of the
powder in toluene/CH2Cl2 (5:1). Mp: 147–149 °C, 1H
NMR (300 MHz, CDCl3) d 7.38–7.2 (m, 15H, ArH), 1.30
(s, 3H, CH3), 1.27 (s, 3H, CH3) 13C NMR (75.45 MHz,
CDCl3) d 14.20 (d, 1JPC = 36 Hz), 59.34 (d, 1JPC = 25 Hz),
127.5 (d, 4JPCCCC = 2 Hz), 128.3, 130.6 (d, 9JPCCC = 5 Hz),
142.3 31P NMR (121.47 MHz, CDCl3) d 27.7 (dm,
JPB = 33 Hz), 11B NMR (28.88 MHz, CDCl3) –32.2 (bs), IR
(KBr, cm-1) 2327 (B-H), 701 (P-B).
Synthesis of 5, Phenyl Tritylphosphinic Acid Benzyl
Ester
Procedure To a solution of trityl H-phenylphosphinic acid
(577 mg, 1.5 mmol) in CHCl3 (8 mL), at rt and under N2
atmosphere, was added benzyl bromide (0.36 mL,
3 mmol). Silver oxide (695 mg, 3 mmol) was added to the
reaction mixture in 5 portions (every 30 min) and stirred at
reflux. After cooling down to rt, the crude mixture was
filtered through celite and the filtrate was then concentrated
in vacuo. The residue was purified by column chromatog-
raphy on silica gel (EtOAc/Hexanes, 2:8 then 1:0),
affording 5 as a white powder. Isolated yield: 80%. Single
crystals for X-ray analysis were obtained from crystals
obtained from: toluene/CH2Cl2/MeOH (5:2:1) Mp: 144–
1
145 °C, H NMR (300 MHz, CDCl3) d 7.53–7.44 (m, 6H,
ArH), 7.41–7.31 (m, 2H, ArH), 7.29–7.14 (m, 15H, ArH),
7.10–7.04 (m, 2H, ArH), 5.10 (dd, JHP = 6 Hz, J = 12 Hz,
1H), 4.82 (dd, JHP = 6 Hz, J = 12 Hz, 1H). 13C NMR
1
(75.45 MHz, CDCl3) d 64.6 (d, JPC = 102 Hz), 66.8 (d,
1
2JPOC = 7 Hz), 127.3, 127.9, 128.1 (d, JPC = 85 Hz),
3
128.13, 128.2, 129.9, 131.5, (d, JPCCC = 6 Hz), 132.2 (d,
2
4JPCCCC = 3 Hz), 134.3 (d, JPCC = 9 Hz), 136.8 (d,
4
3JPOCC = 7 Hz), 141.8 (d, JPCCCC = 3 Hz). 31P NMR
(121.47 MHz, CDCl3) d 43.9 (s), IR (KBr, cm-1) 1214
(P=O), 1006 (P–OH), HRMS (EI) calcd. for C32H27O2P,
(M) 474.1749, found 474.1739.
Synthesis of 6, Trityl phosphonic Acid Diethyl Ester
Synthesis of 4, Phenyl Tritylphosphinic Acid
This compound was prepared according to the literature
[12] via the Arbuzov reaction of (EtO)3P with TrCl in
refluxing benzene (75%). Crystals suitable for X-ray dif-
fraction were obtained from CH2Cl2/toluene.
Procedure To a solution of phenyl H-phosphinic acid
(20.14 g, 0.142 mol) in distilled toluene (100 mL) was
added BSA (70 mL, 0.284 mmol) dropwise at rt, under N2
atmosphere. The reaction mixture was stirred at reflux for
1 h 45 min. Then, a solution of trityl chloride (39.58 mg,
0.142 mol) in toluene (100 mL) was added to the reaction
mixture and the resulting mixture stirred for an additional
13 h at rt. The reaction was quenched by addition of MeOH
Synthesis of 7, Diseleno Tritylphosphinic Acid
Procedure Under N2 atmosphere, elemental selenium
(257 mg; 3.25 mmol) was added to a solution of trityl
123