3
2
LETTER
Enantiospecific sp –sp Stille Coupling of a Chiral Allylstannane
1961
Palladium complex B obviously rearranges in part by
suprafacial migration of the OCb group to form the chiral
vinylpalladium intermediate D, in which the aryl residue
is transferred by expelling the Pd(0).
(7) Typical Procedure.
Pd(PPh ) (50 mg, 0.04 mmol) and ethyl 4-iodobenzoate
3
4
(325 mg, 1.00 mmol) were dissolved under argon in 10 mL
of DMF at r.t. After 15 min (S)-1 (94% ee, 282 mg, 0.50
mmol) were added and the reaction mixture was heated to
60 °C. After the starting material had been completely
consumed (TLC, 12 h) aq sat. NaCl solution (10 mL) was
added. The organic layer was separated and the aqueous
In conclusion, the first enantiospecific Stille coupling was
developed, overcoming one still remaining limitation of
the Stille reaction: coupling of an enantioenriched allyl-
stannane with different aryl halides. In these reactions an
almost complete transfer of chirality from the stannane to
the allylic carbamate is observed.
phase was extracted with Et O (3 × 25 mL). The combined
2
organic extracts were dried over MgSO and the solvents
4
were evaporated in vacuo. The crude product was purified
by flash column chromatography on silica gel (40–63 mm,
Et O–pentane, 1:3).
2
1
Compound (R)-3f: H NMR (400 MHz, CDCl ): d = 1.26,
.32 (m, 12 H, CH -Cb), 1.37 (t, 3 H, H-2¢), 1.46 (d, 3 H,
3
Acknowledgment
1
3
H-4), 3.89 (dq, 1 H, H-3); 4.08 (br s, 2 H, CH-Cb), 4.36
q, 2 H, H-2¢), 5.87 (d, 1 H, H-2), 7.15–7.43, 7.96–7.99 (m,
This work was supported by the Deutsche Forschungsgemeinschaft
(
9
(
SFB 424) and the Fonds der Chemischen Industrie (stipend for
3
H, H-aryl) ppm. Coupling constants: J
= 12.0 Hz,
R.K.).
H-2,H-3
3
3
13
J3-CH3,H-3 = 9.2 Hz, J
= 9.2 Hz. C NMR (100 MHz,
H-1¢,H-2¢
CDCl ): d = 14.2 (C-2¢), 20.4, 21.4, 21.5 (3-CH , CH -Cb),
3
3
3
References and Notes
36.6 (C-3), 46.6 (CH-Cb), 60.6 (C-2¢), 121.5 (C-2), 124.6,
1
26.9, 127.9, 128.2, 128.3, 129.7, 135.8 (C-aryl), 146.0 (C-
), 150.7 (C-aryl), 152.4 (C=O-Cb), 166.5 (C=O–O) ppm.
(
1) Reviews: (a) Stille, J. K. Angew. Chem., Int. Ed. Engl. 1986,
5, 508; Angew. Chem. 1986, 98, 504. (b) Farina, V. In
1
2
IR (film): = 3056, 3030 (Ph–H); 2969, 2923, 2878 (C–H),
Comprehensive Organometallic Chemistry II, Vol. 12; Abel,
E. W.; Stone, F. G. A.; Wilkinson, G., Eds.; Pergamon:
Oxford, 1995, Chap. 4. (c) Mitchell, T. N. In Metal-
Catalyzed Cross-Coupling Reactions, 2nd ed.; Diederich, F.;
de Meijere, A., Eds.; Wiley-VCH: New York, 2004, Chap.
2
1
1
7
343; 1717, 1697 (C=O), 1656, 1631, 1608, 1575, 1554,
538, 1502, 1507, 1474, 1456, 1432, 1366, 1306, 1262,
209, 1183, 1154, 1136, 1119, 1103, 1041, 1026, 892, 854,
56, 704 (Ph–H), 639. MS (Micro-TOF): m/z = 446.2293
+
[M + Na] . R = 0.64 (Et O–PE = 1:1). Chiral HPLC:
f
2
2. (d) Fugami, K.; Kosugi, M. Cross-Coupling Reactions: A
t = 82.5 min; t = 103.4 min (CHIRA-GROM 2, i-PrOH–
R
R
Practical Guide, In Top. Curr. Chem.; Miyaura, M., Ed.;
Springer: New York, 2002, Chap. 4. (e) For mechanistic
aspects, see: Espinet, P.; Echavarren, A. M. Angew. Chem.
Int. Ed. 2004, 43, 4704; Angew. Chem. 2004, 116, 4808.
2) Tang, H.; Menzel, K.; Fu, G. Angew. Chem. Int. Ed. 2003,
n-hexane = 1:500).
20
[
a]D +60 (c 0.53, CHCl , 90% ee, 3R). Anal. Calcd for
3
C H NO (423.24): C, 73.73; H, 7.85; N, 3.31. Found: C,
2
6
33
4
7
3.62; H, 7.99; N, 3.17.
(
(
1
Compound (+)-4f: H NMR (300 MHz, CDCl ): d = 1.20 (t,
3
42, 5079; Angew. Chem. 2003, 115, 5233.
1
2 H, CH -Cb), 1.32 (d, 3 H, H-4), 1.39 (t, 3 H, H-2¢), 3.90
3
3) (a) Labadie, J. W.; Stille, J. K. J. Am. Chem. Soc. 1983, 105,
(
br s, 2 H, CH-Cb), 4.39 (q, 2 H, H-2¢), 5.33 (dq, 1 H, H-3),
6129. (b) Ye, J.; Bhatt, R. K.; Falck, J. R. Tetrahedron Lett.
6.11 (d, 1 H, H-2), 7.19–7.34, 8.05–8.08 (m, 9 H, H-aryl)
1993, 34, 8007. (c) Ye, J.; Bhatt, R. K.; Falck, J. R. J. Am.
3
3
ppm. Coupling constants: J
= 12.0 Hz, J
= 8.8
H-2,H-3
H-3,H-4
Chem. Soc. 1994, 116, 1. (d) Kells, K. W.; Chong, J. M. J.
Am. Chem. Soc. 2004, 126, 15666. For other
enantiospecific coupling reactions, see: (e) Hatanaka, Y.;
Hiyama, T. J. Am. Chem. Soc. 1990, 112, 7793. (f) Arp, F.
O.; Fu, G. C. J. Am. Chem. Soc. 2005, 127, 10482.
3
13
Hz, J
(
2
1
= 9.2 Hz. C NMR (75 MHz, CDCl ): d = 14.7
H-1¢,H-2¢
3
C-2¢), 15.6 (C-4), 21.7 (CH -Cb), 46.2 (CH-Cb), 61.3 (C-
3
¢), 69.7 (C-3), 127.8, 128.1, 128.6, 130.0, 130.7, 139.8,
41.6, 142.3, 143.3, 144.4 (C-aryl), 144.4 (C-1), 155.3
(
C=O-Cb), 166.9 (C=O) ppm. IR (film): 3082, 3056 (Ph–H),
(
1
g) Bhatt, R. K.; Ye, J.; Falck, J. R. J. Am. Chem. Soc. 1995,
17, 5973.
2
1
7
969, 2926, 2901, 2873 (C–H), 1717, 1686 (C=O), 1604,
439, 1400, 1365, 1273, 1213, 1178, 1134, 1095, 1017, 913,
65, 708 (Ph–H) 695 cm . HRMS (ESI): m/z calcd for
(
(
4) Seppi, M.; Kalkofen, R.; Reupohl, J.; Fröhlich, R.; Hoppe,
–1
D. Angew. Chem. Int. Ed. 2004, 43, 1423; Angew. Chem.
+
C H NO : 446.2302 [M + Na] ; found: 446.2285.
2
6
33
4
2
004, 116, 1447.
R = 0.65 (Et O–PE = 1:1). Chiral HPLC: t = 10.4 min;
f
2
R
2
0
20
5) (a) (R)-5a [a]D –11.2 (c 0.81, CCl ); Lit: (–)-(R)-5a [a]
4
D
t = 12.8 min (CHIRA-GROM 2, i-PrOH–n-hexane =
R
–14.8 (c 1.20, CCl ). (b) Tatemitsu, H.; Ogura, F.;
20
4
1:100). [a]D +85 (c 0.51, CHCl , 90% ee). Anal. Calcd for
3
Nakagawa, Y.; Nakagawa, M.; Naemura, K.; Nakazaki, M.
Bull. Chem. Soc. Jpn. 1975, 48, 2473.
C H NO (423.24): C, 73.73; H, 7.85; N, 3.31. Found: C,
2
6
33
4
73.75; H, 7.92; N, 3.14.
(6) (a) Nakamura, H.; Bao, M.; Yamamoto, Y. Angew. Chem.
(
8) Palladium-catalyzed deracemization of allylic compounds:
Int. Ed. 2001, 40, 3208; Angew. Chem. 2001, 113, 3308.
(
(
a) Gais, H. J.; Böhme, A. J. Org. Chem. 2002, 67, 1153.
b) Lussem, B. J.; Gais, H. J. J. Am. Chem. Soc. 2003, 125,
(
b) Kadota, I.; Takamura, H.; Sato, K.; Ohno, A.; Matsuda,
K.; Yamamoto, Y. J. Am. Chem. Soc. 2003, 125, 46.
c) Fernandes, R. A.; Stimac, A.; Yamamoto, Y. J. Am.
Chem. Soc. 2003, 125, 14133.
6066. (c) Trost, B. M.; Organ, M. G. J. Am. Chem. Soc.
(
1994, 116, 1032. (d) Trost, B. M.; Tsui, H.-C.; Toste, F. D.
J. Am. Chem. Soc. 2000, 122, 3534.
Synlett 2006, No. 12, 1959–1961 © Thieme Stuttgart · New York