1-Phosphino-2-sulfenylferrocene Ligands
separated, and the aqueous layer was extracted with Et2O (2
× 20 mL). The combined organic layers were dried (MgSO4)
and filtered, and the solvents were evaporated under reduced
pressure. The residue was purified by flash chromatography
or by precipitation (as indicated in each case). For the
synthesis and characterization data of ferrocenes 3b-j, see
Supporting Information.
2.94 (bs, 2H), 1.23 (s, 9H). 13C NMR (75 MHz): δ 108.9, 71.3,
70.1, 65.8, 63.3, 57.6, 46.5, 30.8. ApcI MS: m/z 290.0 (M++
H), 234.0, 232.9, 201.0. Anal. Calcd for C14H19FeNS: C, 58.14;
H, 6.62; N, 4.48; S, 11.09. Found: C, 58.44; H, 6.47; N, 4.57;
S, 11.11.
(RFc,RS)-1-(ter t-Bu tylsu lfin yl)-2-[(d ip h en ylp h osp h in o)-
m eth yl]fer r ocen e (7). To a solution of 2-hydroxymethyl
sulfinylferrocene 615 (600 mg, 1.87 mmol) in CH2Cl2 (18 mL)
were added Ac2O (400 µL, 2.8 mmol), Et3N (260 µL, 2.8 mmol),
and a catalytic amount of DMAP. The mixture was stirred at
room temperature overnight, and NH4Cl (5 mL) was added.
The organic layer was separated, and the aqueous layer was
extracted with CH2Cl2 (2 × 20 mL). The combined organic
layers were dried (Na2SO4) and filtered, and the solvent was
evaporated. The resulting mixture was purified by flash
chromatography (n-hexanes-EtOAc 2:1) to afford 2-(acety-
loxy)methyl-1-(tert-butylsulfinyl)ferrocene (540 mg, 79%, or-
ange gummy oil). 1H NMR (200 MHz): δ 5.30 (s, 2H, CH2),
4.45 (t, J ) 1.9 Hz, 1H), 4.36 (s, 5H), 4.32 (m, 2H), 2.00 (s,
3H), 1.15 (s, 9H). 13C NMR (50 MHz): δ 170.6, 83.1, 82.4, 72.2,
70.7, 69.9, 60.2, 55.8, 20.8. To a solution of this acetate (400
mg, 1.1 mmol) in AcOH (10 mL) was added HPPh2 (286 µL,
1.65 mmol). The mixture was stirred at 80 °C for 16 h, and
the solvent was evaporated. The resulting mixture was puri-
fied by flash chromatography (n-hexanes-EtOAc 4:1) to afford
(RF c,RS)-1-(ter t-Bu tylsu lfin yl)-2-(d ip h en ylp h osp h in o)-
fer r ocen e (3a ).18 Chlorophosphine: PPh2Cl. Purification by
flash chromatography (n-hexanes-EtOAc 1:1). Yield: 91%,
yellow solid. [R]20 ) -437 (c 0.4, CHCl3) {lit.18 [R]20 ) -303
D
D
(c 3.0, benzene)}; mp 162-163 °C (lit.18 mp 162-163 °C). H
NMR (300 MHz): δ 7.61-7.52 (m, 2H), 7.35-7.28 (m, 3H,),
7.27-7.14 (m, 5H), 4.60-4.56 (m, 1H), 4.53-4.48 (m, 1H),
4.22-4.18 (m, 1H), 4.10 (s, 5H), 0.98 (s, 9H); 13C NMR (75
MHz): 140.6, 140.4, 138.8, 138.6, 135.8, 135.5, 132.9, 132.7,
129.2, 128.1, 127.9, 127.8, 90.1, 89.8, 76.5, 76.2, 75.3, 75.2, 74.0,
72.5, 71.5, 55.9, 23.7. IE MS: m/z 474 (M+, 13), 418 (91), 352
(100), 228 (25), 170 (22).
1
Gen er a l P r oced u r e for Red u ction w ith HSiCl3/Et3N.
To a solution of sulfoxide (0.30 mmol) in toluene (4 mL) were
successively added Et3N (400 µL, 3.0 mmol) and HSiCl3 (400
µL, 4.5 mmol). The mixture was heated at reflux for 12 h, and
it was poured into a mixture of CH2Cl2 (10 mL) and 10%
aqueous solution of NaOH (10 mL). The organic layer was
separated, and the aqueous layer was extracted with CH2Cl2
(2 × 10 mL). The combined organic layers were dried (MgSO4)
and filtered, and the solvents were evaporated. The residue
was purified by flash chromatography. For the synthesis and
characterization data of ferrocenes 1b-j, see Supporting
Information.
the phosphine 7 (530 mg, 98%, orange gummy oil). [R]20
)
D
-239 (c 0.35, CHCl3). 1H NMR (200 MHz): δ 7.60-7.27 (m,
10H), 4.35 (s, 5H), 4.23 (s, 1H), 4.15 (t, J ) 2.4 Hz, 1H), 3.92
(s, 1H), 3.84 (dd, J ) 1.4, 15.4 Hz, 1H), 3.57 (d, J ) 15.6 Hz,
1H), 1.22 (s, 9H). 13C NMR (50 MHz): δ 139.1 (m), 133.2 (d,
J P-C ) 19.7 Hz), 132.2 (d, J P-C ) 18.3 Hz), 128.7-128.2 (m),
85.9 (d, J P-C ) 15.5 Hz), 81.1, 71.5 (d, J P-C ) 9.9 Hz), 71.0,
69.5, 68.8, 56.4, 26.8 (d, J P-C ) 14.1 Hz), 23.5.
(R)-2-(ter t-Bu t ylsu lfen yl)-1-(d ip h en ylp h osp h in o)fer -
r ocen e (1a ). Starting sulfoxide: 3a . Chromatography: n-hex-
Gen er a l P r oced u r e for P d -Ca ta lyzed Allylic Alk yla -
tion of 1,3-Dip h en yl-2-p r op en yl Aceta te w ith Dim eth yl
Ma lon a te. Syn th esis of (R,E)-Meth yl 2-Ca r bom eth oxy-
3,5-d ip h en ylp en t-4-en oa te [(R)-8].35 A mixture of ligand 1
(0.02 mmol) and [Pd(η3-C3H5)Cl]2 (2.3 mg, 0.006 mmol) [and
Bu4NCl (8.8 mg, 0.03 mmol) when it was used] in dry CHCl3
(1 mL) was stirred at room temperature for 1 h, and it was
treated with a solution of 1,3-diphenyl-2-propenyl acetate (80.0
mg, 0.32 mmol) in dry CHCl3 (1 mL). To the resulting mixture
were successively added N,O-bis(trimethylsilyl)acetamide (237
µL, 0.96 mmol) and dimethyl malonate (108 µL, 0.96 mmol).
The reaction was monitored by TLC until the starting material
was consumed (reaction times varied within a wide range: 10-
30 min for ligands 1a -d , 1f, and 1j; 50 min and 3 h for ligands
1g and 1e, respectively, and 50-96 h for ligands 1h -i). Then
it was diluted with diethyl ether and washed with saturated
aqueous NH4Cl solution. The organic layers were dried
(MgSO4) and filtered, and the solvents were evaporated under
reduced pressure. The residue was purified by flash chroma-
tography (n-hexane-EtOAc 7:1) to afford (R)-8 as a colorless
oil. The absolute configuration of the product was assigned
by comparing the sign of its specific rotation with literature
data.35 1H NMR (200 MHz): δ 7.34-7.20 (m, 10H), 6.49 (d, J
) 16.1 Hz, 1H), 6.33 (dd, J ) 8.1, 15.6 Hz, 1H), 4.27 (dd, J )
8.1, 10.7 Hz, 1H), 3.96 (d, J ) 10.7 Hz, 1H), 3.71 (s, 3H), 3.52
(s, 3H). HPLC: Daicel Chiralcel OD, i-PrOH/Hexane 2/98, flow
rate 0.20 mL/min, tR 44.8 min (R)-isomer and 47.2 min (S)-
isomer, 254 nm.
anes-EtOAc 5:1. Yield: 79%, yellow solid. [R]20 ) -200 (c
D
1
0.5, CHCl3); ee > 99%; mp 148-149 °C. H NMR (300 MHz):
δ 7.68-7.58 (m, 2H), 7.39-7.28 (m, 5H), 7.28-7.20 (m, 3H),
4.71-4.67 (m, 1H), 4.50-4.46 (m, 1H), 4.15-4.12 (m, 1H), 3.98
(s, 5H), 1.00 (s, 9H). 13C NMR (75 MHz): δ 139.9, 138.3, 135.3,
135.0, 133.0, 132.7, 128.9, 127.9, 83.1, 81.0, 80.0, 73.4, 71.5,
70.6, 46.0, 31.0. IE MS: m/z 458 (M+, 95), 402 (100), 337 (52),
302 (11), 217 (27), 170 (31), 121 (10). Anal. Calcd for C26H27
-
FePS: C, 68.17; H, 5.94; S, 7.00. Found: C, 67.78; H, 6.10; S,
6.75. HPLC: Daicel Chiralcel OD, i-PrOH/Hexane 0.2/99.8,
flow rate 0.50 mL/min, tR 22.0 min (R)-isomer and 26.1 min
(S)-isomer, 254 nm.
(RF c,RS)-2-Am in o-1-(ter t-bu tylsu lfin yl)fer r ocen e (4).34
To a cold solution (-78 °C) of sulfoxide 2a (0.50 g, 1.72 mmol)
in THF (12 mL) was added a 1.7 M solution of t-BuLi in
pentane (1.22 mL, 2.07 mmol) under argon. The mixture was
stirred at room temperature for 1.5 h, and then a solution of
tosyl azide (0.44 g, 2.24 mmol) was added at -78 °C. The
resulting solution was allowed to reach room temperature for
4 h, and a solution of Bu4N+I- (0.25 g, 0.69 mmol) and NaBH4
(0.26 g, 6.88 mmol) in H2O (5 mL) was added. The reaction
mixture was stirred at room temperature for 12 h, and brine
was added. The organic layer was separated, and the aqueous
layer was extracted with Et2O (2 × 30 mL). The combined
organic layers were dried (MgSO4) and filtered, and the solvent
was evaporated. The resulting mixture was purified by flash
chromatography (CH2Cl2-EtOAc 3:1) to afford the aminosul-
foxide 4 (0.39 g, 75%, orange solid). [R]20 ) -343 (c 0.1,
D
Gen er a l P r oced u r e for P d -Ca ta lyzed Allylic Am in a -
tion of 1,3-Dip h en yl-2-p r op en yl Aceta te w ith Ben zy-
la m in e. Syn t h esis of (S,E)-N-Ben zyl-(1,3-d ip h en yl-2-
p r op en yl)a m in e [(S)-9].36 A mixture of ligand 1 (0.02 mmol)
and [Pd(η3-C3H5)Cl]2 (2.3 mg, 0.006 mmol) in THF (1 mL) was
CHCl3); ee > 98%; mp 163-164 °C. 1H NMR (200 MHz): δ
4.27 (s, 5H), 4.09 (t, J ) 1.8 Hz, 1H), 4.01 (m, 1H), 3.98 (t, J
) 2.5 Hz, 1H), 3.64 (bs, 2H), 1.20 (s, 9H). HPLC: Daicel
Chiralpak AS, i-PrOH/Hexane 5/95, flow rate 0.70 mL/min,
tR 9.9 min (S)-isomer and 12.2 min (R)-isomer, 254 nm.
(R)-2-Am in o-1-(ter t-bu tylsu lfen yl)fer r ocen e (5). Fol-
lowing the general procedure for the reduction with HSiCl3/
Et3N, compound 5 was obtained from 4 in 79% yield as an
orange solid after chromatographic purification (n-hexanes-
(34) Although compound 4 was previously described by us (see ref
12), an improved procedure has been achieved.
(35) Sprinz, J .; Helmchen, G. Tetrahedron Lett. 1993, 34, 1769-
1772.
(36) Hayashi, T.; Yamamoto, A.; Hagihara. T.; Ito, Y. Tetrahedron
Lett. 1986, 27, 191-194.
EtOAc 1:1). [R]20 ) -11 (c 0.15, CHCl3); mp 75-76 °C. 1H
D
NMR (300 MHz): δ 4.13 (m, 2H), 4.06 (s, 5H), 3.96 (s, 1H),
J . Org. Chem, Vol. 68, No. 9, 2003 3685