S. Kobayashi et al.
25.4 Hz), 129.08 (d, J=10.0 Hz), 129.77 (d, J=46.6 Hz), 131.33 (d, J=
10.0 Hz), 131.68 (d, J=2.4 Hz), 175.49 ppm (d, J=3.8 Hz); 31P NMR
(122 MHz, CDCl3): d=38.77 ppm (d, J=40.1 Hz); IR (KBr): n˜ = 2952,
2398, 2355, 1699, 1418, 1300, 1063 cmÀ1; MS (ESI): m/z: 245.1 ([M+Na+]);
Preparation of 1-phenyl-2-trimethylstannylphospholane borane complex
(7): To a stirred solution of TMEDA (11.89 g, 102 mmol) in Et2O, sBuLi
(115.7 mL of 0.88m hexane–cyclohexane solution, 102 mmol) was added
at À788C, and then after 1 h, 3 (12.14 g in 130 mL of Et2O) was added.
After 1.5 h, trimethylstannyl chloride (23.10 g in Et2O (70 mL)) was
added, and the mixture was further stirred for 12 h and allowed to warm
to room temperature slowly. Then, 1n aq. HCl (200 mL) was added to
quench the reaction. The organic layer was separated, and the aqueous
layer was extracted with EtOAc three times. The combined extracts were
washed with water twice, dried over Na2SO4, concentrated, and purified
by column chromatography (SiO2, hexane/Et2O=10:1–6:1). The two dia-
stereomers were separated by fractional recrystallization (trans-7 from
hexane first, cis-7 from Et2O), followed by the column chromatography
of the mother liquor (SiO2, hexane/Et2O=50:1). Yields: 56% (trans-7),
39% (cis-7).
elemental analysis calcd for C11H16BO2P:
C 59.33, H 7.24.
C 59.50, H 7.26; found:
Methyl (1R,2S)-1-phenylphospholane-2-carboxylate borane complex:
Colorless prisms; m.p. 109–1118C; [a]2D8 =À166.68 (c=1.17 in CHCl3);
1H NMR (300 MHz, CDCl3): d=0.70 (q, J=107.1 Hz, 3H), 1.95–2.04 (m,
1H), 2.12–2.38 (m, 5H), 3.23–3.34 (m, 1H), 3.76 (s, 3H), 7.45–7.56 (m,
3H), 7.73–7.79 ppm (m, 2H); 13C NMR (75 MHz, CDCl3): d=26.37 (d,
J=1.3 Hz), 26.55 (d, J=36.6 Hz), 29.97 (d, J=5.0 Hz), 46.14 (d, J=
26.0 Hz), 52.27, 129.06 (d, J=9.9 Hz), 130.11 (d, J=46.6 Hz), 131.32 (d,
J=9.4 Hz), 131.61 (d, J=2.5 Hz), 170.36 ppm (d, J=3.1 Hz); 31P NMR
(122 MHz, CDCl3): d=39.23 ppm (d, J=60.8 Hz); IR (KBr): d=3064,
2959, 2875, 2373, 1741, 1438, 1206 cmÀ1; MS (ESI): m/z: 259.1 ([M+Na+]);
elemental analysis calcd (%) for C12H18BO2P: C 61.06, H 7.69; found:
C 61.07, H 7.77.
trans-1-Phenyl-2-trimethylstannylphospholane borane complex (trans-7):
colorless prisms; m.p. 90.5–90.68C; 1H NMR (300 MHz, CDCl3): d=
0.11–1.30 (m, 13H), 1.72–2.45 (m, 6H), 7.40–7.50 (m, 3H), 7.69–7.77 ppm
(m, 2H); 13C NMR (75 MHz, CDCl3): d=À8.37, 22.40 (d, J=18.0 Hz),
27.48 (d, J=34.1 Hz), 28.79 (d, J=2.5 Hz), 31.92 (d, J=1.9 Hz), 128.70
(d, J=9.9 Hz), 130.81 (d, J=2.5 Hz), 131.41 (d, J=9.4 Hz), 133.08 ppm
(d, J=42.8 Hz); 31P NMR (122 MHz, CDCl3): d=32.83 (q, J=65.6 Hz);
IR (KBr): n˜ =2952, 2373, 1436, 1059 cmÀ1; MS (ESI): m/z: 363 ([M+Na+]);
elemental analysis calcd (%) for C13H24BPSn: C 45.81, H 7.10; found:
C 45.59, H 7.15.
Determination of the absolute configuration of 2: The absolute configu-
ration of 2 was determined by X-ray crystal structure analysis of the (+)-
menthyl ester of the (1R,2R)-1-phenylphospholane-2-carboxylic acid
borane complex cis-6. (+)-Menthol (234.4 mg, 1.5 mmol), DMAP
(7.8 mg, 0.05 mmol) in CH2Cl2 (5 mL), and DCC (247.4 mg, 1.2 mmol)
were added to a solution of (1R,2S)-1-phenylphospholane-2-carboxylic
acid borane complex 2 (222.0 mg, 1 mmol). The mixture was stirred for
6 h at room temperature, quenched with 1n aq. HCl (3 mL), extracted
with CH2Cl2, concentrated, and purified by PTLC (SiO2, hexane/
AcOEt=10:1) to afford trans-6 (51%) and cis-6 (43%).
cis-1-Phenyl-2-trimethylstannylphospholane borane complex (cis-7): col-
orless prisms; m.p. 103.6–104.28C; 1H NMR (300 MHz, CDCl3): d=
À0.17 (s, 9H), 0.38–1.37 (m, 4H), 1.63–1.85 (m, 2H), 2.03–2.41 (m, 4H),
7.37–7.49 (m, 3H), 7.65–7.72 ppm (m, 2H); 13C NMR (75 MHz, CDCl3):
d=À9.77, 23.51 (d, J=23.6 Hz), 26.50 (d, J=34.7 Hz), 28.53 (d, J=
1.9 Hz), 32.58, 128.59 (d, J=9.3 Hz), 131.21 (d, J=2.5 Hz), 132.32 (d, J=
9.3 Hz), 132.34 ppm (d, J=47.2 Hz); 31P NMR (122 MHz, CDCl3): d=
34.75 ppm (q, J=36.2 Hz); IR (KBr): n˜ =3049, 2970, 2945, 2858, 2370,
2332, 1437, 1061 cmÀ1; MS (ESI): m/z: 363 ([M+Na+]); elemental analy-
sis calcd (%) for C13H24BPSn: C 45.81, H 7.10; found: C 45.71, H 7.02.
(+)-Menthyl (1R,2S)-1-phenylphospholane-2-carboxylate borane com-
plex (trans-6): More polar than cis-6, colorless needles; m.p. 94.5–95.58C;
[a]2D0 =+69.98 (c=1.00 in EtOH); 1H NMR (300 MHz, CDCl3): d=0.30–
2.36 (m, 27H), 3.16–3.26 (m, 1H), 4.69–4.78 (m, 1H), 7.45–7.56 (m, 3H),
7.73–7.80 ppm (m, 2H); 13C NMR (75 MHz, CDCl3): d=16.37, 20.73 ,
22.01, 23.46, 26.07 (d, J=23.61 Hz), 26.33 (d, J=36.6 Hz), 30.10 (d, J=
5.6 Hz), 31.47, 34.19, 40.85, 46.24 (d, J=26.7 Hz), 47.04, 75.81, 128.97 (d,
J=11.3 Hz), 130.58 (d, J=49.3 Hz), 131.31 (d, J=9.4 Hz), 131.42 (d, J=
2.4 Hz), 169.24 ppm (d, J=3.1 Hz); 31P NMR (122 MHz, CDCl3): d=
37.17 ppm (d, J=52.3 Hz); IR (KBr): n˜ =2957, 2872, 2397, 2360, 1724,
1443 cmÀ1; MS (ESI): m/z 383.2 ([M+Na+]); elemental analysis calcd
(%) for C21H34BO2P: C 70.01, H 9.51; found: C 69.82, H 9.29.
Typical experimental procedure for the lithiodestannylation–carboxyla-
tion in Et2O: nBuLi (1.49m hexane solution, 1.5 mmol) was added to a
stirred solution of an amine (1.5 mmol) in Et2O (4 mL) at À1008C over
5 min. After 5 min, 1-phenyl-2-trimethylstannylphospholane borane com-
plex 7 (0.5 mmol in 5 mL of Et2O solution) was added over 5 min, and
then after 5 min CO2 (gas) was bubbled through the mixture for 30 min.
H2O–MeOH (1:1, 5 mL) followed by 1n aq. HCl (5 mL) were added.
The mixture was extracted with CH2Cl2 three times, and purified by
PTLC (SiO2, hexane/Et2O=20:1, then hexane/AcOEt=1:1). The yields
and the diastereomer ratios of 2-mixture are listed in Table 2.
(+)-Menthyl (1R,2R)-1-phenylphospholane-2-carboxylate borane com-
plex (cis-6): Less polar than trans-6, colorless needles; m.p. 128.2–
128.38C; [a]2D0 =+32.38 (c=1.00 in EtOH); 1H NMR (300 MHz, CDCl3):
d=0.20–2.39 (m, 27H), 3.24–3.33 (m, 1H), 4.23–4.31 (m, 1H), 7.43–7.51
(m, 3H), 7.72–7.79 ppm (m, 2H); 13C NMR (75 MHz, CDCl3): d=15.46,
20.87, 21.89, 22.70, 25.23 (d, J=7.5 Hz), 27.78 (d, J=36.0 Hz), 31.20,
31.77 (d, J=1.9 Hz), 33.95, 40.42, 46.23, 46.54 (d, J=27.3 Hz), 127.18 (d,
J=43.5 Hz), 128.68 (d, J=10.0 Hz), 131.97 (d, J=2.5 Hz), 133.23 (d, J=
10.0 Hz), 169.13 ppm (d, J=3.7 Hz); 31P NMR (122 MHz, CDCl3): d=
35.24 ppm (d, J=55.9 Hz); IR (KBr): n˜ =2957, 2863, 2397, 1716,
1439 cmÀ1; MS (ESI): m/z: 383.2 ([M+Na+]); elemental analysis calcd
(%) for C21H34BO2P: C 70.01, H 9.51; found: C 69.88, H 9.30.
Preparation of the single crystals of DPE-coordinated trans-1-phenyl-2-
phospholanyllithium (9): sBuLi (0.87m hexane–cyclohexane solution,
1.53 mmol) was added at À788C to a stirred solution of 1,2-dipiperidino-
ethane (DPE, 0.33 g, 1.70 mmol) in Et2O (2 mL). After 30 min,
3
(1.13 mmol in Et2O (2 mL)) was added, and the reaction mixture became
turbid yellow over 1.5 h. After warming to about 408C, the turbid so-
lution became clear, and the mixture was filtered through a glass filter
(G4). After about 12 h at À488C, light yellow crystals appeared. The
light yellow crystals were washed with Et2O and then hexane (twice),
and were stored in a mineral oil. 9: 1H NMR (600 MHz, [D10]Et2O,
0.147m): d=0.32 (d, J=4.4 Hz, 1H), 0.80 (q, J=250 Hz, 3H), 1.37 (s,
4H), 1.58 (t, J=5.5 Hz, 8H), 1.66–1.72 (m, 2H), 1.82–1.85 (m, 1H), 1.95–
2.00 (m, 1H), 2.17–2.25 (m, 1H), 2.37–2.47 (m, 13H), 7.10–7.17 (m, 3H),
7.57–7.60 ppm (m, 2H); 13C NMR (125 MHz, [D10]Et2O, 0.147m): d=
13.8, 25.07, 26.10, 27.37 (d, J=2.1 Hz), 30.55 (d, J=43.39 Hz), 34.73 (d,
J=5.1 Hz), 56.16, 57.00, 128.02 (d, J=7.3 Hz), 128.45 (d, J=2.1 Hz),
131.29 ppm (d, J=8.3 Hz), another signal of a carbon was covered by the
otherꢁs signal; 31P NMR (122 MHz, [D10]Et2O0): d=28.67 ppm (q, J=
(1R,2S)-1-Phenylphospholane-2-carboxylic acid (1): Pyrrolidine (8 mL)
was added to a solution of (1R,2S)-1-phenylphospholane-2-carboxylic
acid borane complex 2 (0.90 g, 4.0 mmol) in benzene (8 mL). The so-
lution was stirred for 6 h at 408C, and concentrated, and the residue was
dissolved in CH2Cl2 (2 mL). 1n aq. HCl (15 mL) was added to decom-
pose the pyrrolidine–borane complex, and then the product was extract-
ed with CH2Cl2 and purified by column chromatography (SiO2, hexane/
AcOEt=1:1) to afford 1 (84%). White solid; m.p. 69.8–69.98C; [a]D28
=
À120.58 (c=0.60 in EtOH); 1H NMR (300 MHz, CDCl3): d=1.72–2.26
(m, 6H), 3.10–3.16 (m, 1H), 7.25–7.52 ppm (m, 5H); 13C NMR (75 MHz,
CDCl3): d=26.80 (d, J=14.26 Hz), 28.69 (d J=3.77 Hz), 31.16, 48.97 (d,
J=21.1 Hz), 128.09, 128.55 (d, J=5.6 Hz), 130.32 (d, J=16.2 Hz), 140.07
(d, J=24.8 Hz), 182.42 ppm (q, J=16.8 Hz); 31P NMR (122 MHz,
6
91.1 Hz); Li NMR (88 MHz, [D10]Et2O, 0.0938m): d=0.81 (rt), 1.16 ppm
(2J(6Li,31P)=2.3 Hz, À1008C); 7Li NMR (233 MHz, [D10]Et2O, 0.147m):
6
CDCl3): d=9.72 ppm; IR (KBr): n˜ =3184, 2945, 1718, 1433, 1142 cmÀ1
;
d=0.91 (s, rt), 1.22 ppm (s, À1008C). Li-labeled 9 was prepared by using
HRMS (ESI): m/z calcd for C11H13O2P ([M+H+]) 209.0731, found
sBu6Li (0.66m hexane solution) instead of sBuLi according to the same
209.0735.
procedure.
366
ꢀ 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2005, 11, 361 – 368