Ferrocenyl Dialkylphosphines for Cross-Couplings
from ether at -30 °C. 1H NMR (300 MHz, C6D6) δ 1.13 (d, J )
11.1 Hz, 18H), 3.22 (s, 15H), 4.51 (br s, 2H), 4.73 (br s, 2H),
6.62 (d, J ) 8.7 Hz, 10H), 7.47 (d, J ) 8.7 Hz, 10H); 13C NMR
(75 MHz, C6D6) δ 31.4 (d, J ) 13.5 Hz), 33.4 (d, J ) 24.6 Hz),
54.5, 76.3, 78.4 (d, J ) 11.1 Hz), 84.8 (d, J ) 39.9 Hz), 87.6,
113.1, 128.6, 134.3, 158.6; 31P{1H} NMR (300 MHz, C6D6) δ
26.5, Anal. Calcd for C53H57O5PFe: C, 73.95; H, 6.67. Found:
C, 73.76; H, 6.40.
and sodium tert-butoxide (144 mg, 1.50 mmol). Anhydrous
toluene (2 mL) was added into the mixture, and the vial was
then sealed with a cap containing PTFE septum. The reaction
mixture was stirred at room temperature for 1 h. After the
starting aryl halide was consumed, as determined by GC, the
reaction solution was directly adsorbed onto silica gel, and the
product was isolated by eluting with hexane/ethyl acetate to
give 244 mg (99%) of triphenylamine as a white solid. Reaction
of chlorobenzene (62 mg, 0.55 mmol) with diphenylamine (85
mg, 0.50 mmol) proceeded at 80 °C over 21 h to give triphen-
ylamine (121 mg, 98%). 1H NMR (400 MHz, CDCl3): δ 7.26 (t,
6H, 7.2 Hz), 7.11 (d, 6H, 7.6 Hz), 7.02 (app.t, 3H, 7.2 and 7.6
Hz). 13C{1H} NMR (100 MHz, CDCl3): δ 147.83, 129.17,
124.14, 122.63. GC/MS (EI): m/z 245 (M+).
P (C5H4F eC5HP h 4)(t-Bu )2. A mixture of P(C5H4FeC5H5)(t-
Bu)2 (0.500 g, 1.500 mmol), Pd(OAc)2 (0.0175 g, 0.0781 mmol),
and NaOC6H4-4-OCH3 (2.230 g, 15.30 mmol) was dissolved in
PhCl (17.10 g, 152.0 mmol) and heated at 110 °C for 18 h.
The solution was filtered through Celite, and PhCl was
removed in vacuo. The solid materials were redissolved in
THF, concentrated, and layered with pentane at -35 °C. A
bulk sample that was analytically pure was not available, but
a sample of roughly 80% purity containing orange crystals of
the tetraphenylferrocenyl phosphine was obtained (0.451 g,
47.4%). 1H (C6D6): δ 1.09 (d, 11.1 Hz, 18H, CMe3), 4.01 (broad
s, 2H, C5H4), 4.33 (t, 1.7 Hz, 2H, C5H4), 5.01 (s, 1H, C5HPh4),
6.93-7.14 (m, 12H, m,p-C5HPh4), 7.30 (dd, 7.2 Hz, 0.9 Hz, 4H,
o-C5HPh4), 7.66 (dd, 7.7 Hz, 1.7 Hz, 4H, o′-C5HPh4). 13C{1H} δ
31.00 (d, 13.6 Hz, CMe3), 33.01 (d, 22.4 Hz, CMe3), 76.51 (s,
CHC4Ph4), 77.15 (s, C5H4), 78.31 (d, 9.7 Hz, C5H4), 81.86 (d,
33.6 Hz, ipso-C5H4), 87.50 (s, CHC4Ph4), 88.12 (s, CHC4Ph4),
126.70 (s, C5HPh4), 127.68 (s, C5HPh4), 127.90 (s, C5HPh4),
130.99 (s, C5HPh4), 131.05 (s, C5HPh4), 132.68 (s, C5HPh4),
136.66 (s, C5HPh4), 137.87 (s, C5HPh4). 31P{1H} NMR (C6D6):
δ 25.34 (s). HRMS: m/e Calcd, 634.2452; Found, 634.2444.
Gen er a l Meth od s. P r oced u r e B. A typical procedure is
given for the reaction of entry 6 in Table 7. A 4 mL vial was
charged with 4-tert-butylbromobenzene (108 mg, 0.51 mmol),
Pd(OAc)2 (3.1 mg, 1 mol %), Ph5FcP(t-Bu)2 (7.1 mg, 2 mol %),
and sodium tert-butoxide (60 mg, 0.60 mmol). Anhydrous
toluene was added, and the vial was sealed with a cap
containing PTFE septum and removed from the drybox. 80
mL of n-hexylamine was added to the vial through the septum
using a syringe. Reaction mixture was then heated to 100 °C
for 2 h to give the title compound (113 mg, 95%) as a colorless
1
oil. H NMR (300 MHz, CDCl3): δ 7.26 (d, 2H, 8.4 Hz), 6.62
(d, 2H, 8.4 Hz), 3.51 (bs, 1H), 3.14 (t, 2H, 7.2 Hz), 1.66 (m,
2H), 1.34-1.43 (m, 6H), 1.34 (s, 9H, t-Bu), 0.96 (t, 3H, 6.3 and
6.9 Hz). 13C{1H} NMR (100 MHz, CDCl3): δ 146.14, 139.75,
125.92, 112.35, 44.11, 33.76, 31.63, 31.53, 29.58, 26.86, 22.62,
14.05. GC/MS(EI): m/z 233 (M+). Anal. Calcd for C16H27N: C,
82.34; H, 11.82; N, 6.00. Found: C, 82.55; H, 11.82; N, 6.06.
P [C5H4F eC5(3,5-Me2C6H3)5](t-Bu )2. A mixture of P(C5H4-
FeC5H5)(t-Bu)2 (200 mg, 0.606 mmol), Pd(OAc)2 (14 mg, 0.061
mmol), and NaO-t-Bu (582 mg, 6.06 mmol) was dissolved in
11.2 g (60.6 mmol) of 5-bromo-m-xylene and heated at 110 °C
for 18 h. The solution was filtered through Celite and then
concentrated by heating at 80 °C under vacuum. The product
was isolated from the crude concentrated solution by silica gel
chromatography. A yellow byproduct fraction eluted first with
an eluent of 100:1 pentane Et2O. The red product was then
eluted with a 80:1 mixture of pentane/Et2O to give 154 mg
(30%) of P[C5H4FeC5(3,5-Me2C6H3)5](t-Bu)2 as a red solid that
Rea ction s of Ar yl Ha lid es w ith Bor on ic Acid s. Gen er a l
P r oced u r e A. A typical procedure is given for the reaction of
entry 1 in Table 10. A 4 mL vial was charged with 4-bro-
mobenzophenone (268 mg, 1.03 mmol), o-tolylboronic acid (152
mg, 1.12 mmol), KF (116 mg, 2.00 mmol), Pd(dba)2 (5.8 mg, 1
mol %), and Ph5FcP(t-Bu)2 (7.1 mg, 2 mol %). Anhydrous
toluene (2 mL) was added to the mixture, and the vial was
sealed with a cap containing PTFE septum and removed from
the drybox. The reaction solution was stirred at room tem-
perature for 18 h. After the starting aryl halide was consumed,
the reaction solution was directly absorbed onto silica gel, and
the coupling product was isolated by eluting with hexane/ethyl
acetate to give 275 mg (98%) of 4-(2-methylphenyl)benzophen-
one as a solid.
1
was judged to be roughly 95% pure by H NMR spectroscopy.
1H NMR δ 7.27 (s, 10 H), 6.70 (s, 5 H), 4.83 (q, 1.6 Hz, 2 H),
4.68 (t, 1.6 Hz, 2 H), 2.07 (s, 30 H), 1.12 (d, 10.8 Hz, 18 H);
31P{1H} NMR (C6D6): δ 26.11 (s).
P (C5H5F eC5Me5)P (t-Bu )2. Cp*H (97 mg, 071 mmol) was
dissolved in 3 mL of THF. n-BuLi (0.285 mL of a 2.5 M
solution, 0.713 mmol) was added dropwise, and the solution
was stirred for 15 min to precipitate Cp*Li. Fe(acac)2 (181 mg,
0.713 mmol) was added, and the solution was stirred for 20
min. In a separate vial, C5H5P(t-Bu)2 (200 mg, 0.951 mmol),
which was prepared from NaCp and ClP(t-Bu)2, was treated
with 0.285 mL of a 2.5 M solution of BuLi (0.71 mmol) of
n-BuLi at room temperature in 3 mL of THF. The resulting
Li[C5H4P(t-Bu)2] was added to the solution of Cp* iron complex,
and the resulting mixture was stirred for 16 h. After this time,
the solution was filtered through Celite and the solvent
evaporated. Silica gel chromatography was conducted under
nitrogen first washing the column with pentane and then
eluting product with a 4:1 mixture of pentane and toluene.
The product fractions were combined, the solvent was removed,
and the product was recrystallized from pentane to provide
51 mg (18%) of product. 1H NMR δ 1.25 (d, 10.8 Hz, 18 H),
1.81 (s, 15 H), 3.686 (t, 1.4 Hz, 2 H), 3.85 (broad s, 2H); 13C
NMR δ 11.499 (s), 31.20 (d, 13.8 Hz), 32.90 (d, 24 Hz), 73.74
Gen er a l P r oced u r e B: A typical procedure is given for
the reaction of entry 1 in Table 13. A 4 mL vial was charged
with 4-tert-butylbromobenzene (213 mg, 1.00 mmol), Pd(dba)2
(5.8 mg, 1 mol %), Ph5FcP(t-Bu)2 (14.2 mg, 2 mol %), K3PO4
(430 mg, 2.02 mmol, powdered), and n-butylboronic acid (124
mg, 1.21 mmol). Anhydrous toluene (2 mL) and a stirring bar
were added, and the vial was then sealed with a cap containing
a PTFE septum and removed from the drybox. The reaction
mixture was stirred at 100 °C for 2.5 h. After the starting aryl
halide was consumed as determined by GC, the reaction
solution was cooled to room temperature. The reaction solution
was then adsorbed onto silica gel directly, and the product was
isolated by eluting with ethyl acetate/hexanes to give 175 mg
(92%) of 4-tert-butyl-1-n-butylbenzene as colorless oil. Kugel-
rohr distillation was used for further purification.
Gen er al P r ocedu r e for th e For m ation of Diar yl Eth er s.
A 4 mL vial was charged with 2-bromotoluene (86 mg, 0.50
mmol, Pd(dba)2, 14 mg (0.025 mmol), Ph5FcP(t-Bu)2 (26 mg,
0.38 mmol), and sodium p-methoxyphenoxide (88 mg, 0.60
mmol). Anhydrous toluene (2.5 mL) was added, and the vial
was sealed with a cap containing a PTFE septum and removed
from the drybox. The reaction mixture was heated at 40 °C
for 24 or 70 h at room temperature. The reaction solution was
then adsorbed onto silica gel, and the product was isolated by
eluting with ethyl acetate/hexanes (0 to 10% gradient) to give
(d, 2.2 Hz), 74.17 (d, 10.0 Hz), 79.01 (d, 31.1 Hz), 80.08 (s); 31
P
NMR 23.06 (s). Anal. Calcd for C23H37FeP C, 69.00; H 9.32.
Found: C, 68.82, H, 9.37.
Am in a tion of Ar yl Ha lid es. Gen er a l Meth od s. P r oce-
d u r e A. A typical procedure is given for the reaction of entries
1 and 2 in Table 1. A 4 mL vial was charged with bromoben-
zene (171 mg, 1.10 mmol), diphenylamine (169 mg, 1.00 mmol),
Pd(dba)2 (5.9 mg, 1 mol %), Ph5FcP(t-Bu)2 (7.1 mg, 2 mol %),
1
106 mg (99%) of diaryl ether. H NMR (CDCl3) δ 2.33 (s, 3H),
3.83 (s, 3H), 6.83-6.96 (m, 5H), 7.05 (t, 7.4 Hz, 1H), 7.16 (t,
J . Org. Chem, Vol. 67, No. 16, 2002 5565