(
1.06 g, 4 mmol) was added and the mixture was stirred at rt for 50 h,
poured into water and extracted with Et O (36). The organic layers were
dried (MgSO ) and the solvent was distilled at normal pressure.
Chromatography (SiO , Et O : pentane 1 : 20) yielded 800 mg (87%) of
as a colourless oil (ee . 98%, HPLC, [a]2 = +4u (c= 0.82 CDCl
8 H. Ovaa, C. Stapper, G. A. V. D. Marel, H. S. Overkleeft, J. H. V.
Boom and S. Blechert, Tetrahedron, 2002, 58, 7503–7518.
9 (a) U. Voigtmann and S. Blechert, Synthesis, 2000, 6, 893–898; (b)
J. Neidh o¨ fer and S. Blechert, Synthesis, 2004, 18, 3047–3054.
10 (a) N. Holub, J. Neidh o¨ fer and S. Blechert, Org. Lett., 2005, 7,
1227–1229; (b) S. Basra and S. Blechert, Strategies and Tactics in
Organic Synthesis, ed. M. Harmata, Elsevier, Amsterdam, 2004, vol. 4,
pp. 315–346.
11 C. M. Huwe, J. Velder and S. Blechert, Angew. Chem., 1996, 108,
2542–2544, Angew. Chem., Int. Ed., 1996, 35, 2376–2378.
12 Y.-i. Fukuda, M. Shindo and K. Shishido, Heterocycles, 2004, 62,
787–792.
2
4
2
2
0
D
1
4
3
)). H-
): d = 7.28 (d, J = 8.3 Hz, 2H), 6.88 (d, J = 8.3 Hz,
H), 5.95 (ddd, J = 17.2, 10.2, 6.5 Hz, 1H), 5.66–5.69 (m, 2H), 5.22 (dd, J =
7.2, 1.5 Hz, 1H), 5.14 (dd, J = 10.2, 1.5 Hz, 1H), 4.78 (d, J = 6.5 Hz, 1H),
NMR (500 MHz, CDCl
2
1
3
13
4
(
1
5
.28 (dt, J = 7.2, 3.7 Hz, 1H), 3.80 (s, 3H), 2.35–2.60 (m, 4H). C-NMR
125.8 MHz): d = 159.0 (C), 139.6 (CH), 133.6 (C), 128.4 (CH), 128.3 (CH),
28.2 (CH), 128.1 (CH), 115.6 (CH ), 113.8 (CH), 80.5 (CH), 76.5 (CH),
5.3 (CH ), 39.5 (CH ), 39.3 (CH
2
3
2
2
), 27.8 (CH). IR (ATR): 3062 (m),
2
930 (m), 2835 (m), 1161 (m), 1511 (vs), 1247 (vs), 1036 (m), 925 (m),
13 (a) Y.-i. Fukuda, H. Sasaki, M. Shindo and K. Shishido, Tetrahedron
Lett., 2002, 43, 2047–2049; (b) Y. Murakami, M. Shindo and
K. Shishido, Synlett, 2005, 664–666.
14 V. B o¨ hrsch, J. Neidh o¨ fer and S. Blechert, Angew. Chem., 2006, 118,
1324–1327, Angew. Chem., Int. Ed., 2006, 45, 1302–1305.
15 C. Shu and J. F. Hartwig, Angew. Chem., 2004, 116, 4898–4901, Angew.
Chem., Int. Ed., 2004, 43, 4794–4797.
16 F. Houliken, F. Bouchard, J. M. Frechet and C. G. Wilson, Can. J.
Chem., 1985, 63, 153–162.
17 Selected reviews: (a) T. Graening and H. -G. Schmalz, Angew. Chem.,
2003, 115, 2684–2688, Angew. Chem., Int. Ed., 2003, 42, 2580–2584; (b)
A. Pfalz, Chimia, 2004, 58, 49–50.
18 (a) B. M. Trost and M. U. Frederiksen, Angew. Chem., 2005, 117,
312–314, Angew. Chem., Int. Ed., 2005, 44, 308–310; (b) L. Acemoglu
and J. M. J. Williams, Palladium-Catalyzed Asymmetric Allylation and
Related Reactions, John Wiley & Sons, Hoboken, 2002 and references
cited within.
19 (a) S.-K. Kang, D.-C. Park, J.-H. Jeon, H.-S. Rho and C.-M. Yu,
Tetrahedron Lett., 1994, 35, 2357–2360; (b) S.-L. You, X.-Z. Zhu, Yu-
Mei Luo, X.-L. Hou and L.-X. Dai, J. Am. Chem. Soc., 2001, 123,
+
+
827 (m). EI-MS: 230 (12, [M] ), 163 (30, [M 2 C
5 7
H ] ), 147 (100, [M 2
+
+
C
7
5
H
7
O] ). HR-MS calc.: [M] : 230.1308, found: 230.1307. EA calc.: C
8.23%, H 7.88%, found: C 77.80%, H 7.91%.
-(4-Methoxy-phenyl)-2-propenyl-3,6-dihydro-2H-pyran (2): 230 mg
1 mmol) of 4 were dissolved in benzene (c = 0.02 M), which had been
6
(
saturated with ethylene in a pressure vessel (0.33 L). 85 mg (0.1 mmol)
Grubbs II catalyst was added in two portions and the reaction mixture was
heated to 50 uC for 6 h. The conversion was monitored via GC-MS.
Subsequently, 15 mg (0.4 mmol) of NaBH
4
were added. The vessel was
flushed with nitrogen and heated for 30 h to 100 uC. The solvent was
distilled over a Vigreux-column and the residue was purified by flash
chromatography (SiO , Et O : pentane 1 : 100) to yield 130 mg (60%) of the
2
2
product contaminated with 5% impurity (trans-isomer of the non-
1
isomerised RRM product). H-NMR (500 MHz, CDCl
.29 (d, J = 8.3 Hz, 2H), 6.87 (d, J = 8.3 Hz, 2H), 5.89–5.94 (m, 1H), 5.69–
.74 (m, 2H), 5.59 (ddq, J = 15.5, 6.6, 1.5 Hz, 1H), 5.17 (bs, 1H), 4.21 (ddd,
J = 7.0, 6.5, 3.0 Hz, 1H), 3.79 (s, 3H), 2.20–2.30 (m, 1H), 2.01–2.08 (m,
3
, 25 uC): d =
7
5
13
1
(
1
3
H), 1.69 (dd, J = 6.6, 1.5 Hz, 3H). NOE (5.17 A 4.21: 1.9%). C-NMR
125.8 MHz): d = 160.7 (C), 133.7 (C), 131.9 (CH), 130.2 (CH), 128.7 (CH),
12.8 (CH), 124.5 (CH), 113.8 (CH), 77.3 (CH), 75.0 (CH), 55.3 (CH ),
1.0 (CH ), 17.8 (CH ). IR (ATR): 3435 (m), 3035 (vw), 2926 (w), 2854 (w),
703 (vw), 1598 (w), 1325 (m), 1158 (vs), 1095 (m), 815 (m). EI-MS: 230
7
471–7472; (c) W.-H. Zheng, N. Sun and X.-L. Hou, Org. Lett., 2005, 7,
151–5154 and references cited within.
0 (a) G. Lipowsky and G. Helmchen, Chem. Commun., 2004, 116–117; (b)
G. Lipowsky, N. Miller and G. Helmchen, Angew. Chem., 2004, 116,
695–4698, Angew. Chem., Int. Ed., 2004, 43, 4595–4597; (c) H. Miyabe
3
5
2
3
2
1
+
+
+
(
20, [M] ), 187 (30, [M 2 C
3
H
7
] ), 135 (100), 108 (15, [C
calc. [M] : 230.1307, found: 230.1306.
2)-Centrolobine (1): To 22 mg (0.1 mmol) 2 and 24 mg (0.2 mmol) 3 in
.2 mL toluene, 6.2 mg (0.01 mmol) Hoveyda–Blechert catalyst were added
and the mixture was stirred at rt overnight. Subsequently, 6 mg Pd/C (5%,
0 wt% H O) were added and an H atmosphere was introduced. The
7 8
H O] ). HR-MS:
+
4
31
and Y. Takemoto, Synlett, 2005, 11, 1641–1655; (d) D. Polet and
A. Alexakis, Org. Lett., 2005, 7, 1621–1624; (e) C. Shu, A. Leitner and
J. F. Hartwig, Angew. Chem., 2004, 116, 4901–4904, Angew. Chem., Int.
Ed., 2004, 43, 4797–4800.
(
0
5
2
2
2
1 (a) C. A. Kiener, C. Shu, C. Incarvito and J. F. Hartwig, J. Am. Chem.
Soc., 2003, 125, 14272–14273; (b) F. Lopez, T. Ohmura and
J. F. Hartwig, J. Am. Chem. Soc., 2003, 125, 3426–3427.
mixture was stirred for 4 d at rt and filtered over a pad of cotton wool. The
solvent was evaporated and the product was purified by flash chromato-
graphy (SiO
obtained. The spectroscopic data were consistent with the literature. H-
NMR (500 MHz, CDCl ): d = 7.31 (d, J = 8.5 Hz, 2H), 7.05 (d, J = 8.8 Hz,
H), 6.87 (d, J = 8.5 Hz, 2H), 6.74 (d, J = 8.8 Hz, 2H), 4.59 (bs, 1H), 4.29
dd, J = 11.1, 2.0 Hz, 1H), 3.80 (s, 3H), 3.44 (dddd, J =12.6, 6.4, 4.7, 1.8 Hz,
H), 2.78–2.60 (m, 2H), 1.96–1.82 (m, 4H), 1.79–1.70 (m, 1H), 1.69–1.50
2
, EtOAc : hexane 1 : 15–1 : 10). 14 mg (50%) of 1 were
3 1
22 P. Schwab, M. B. France, J. W. Ziller and R. H. Grubbs, Angew.
Chem., 1995, 107, 2179–2181, Angew. Chem., Int. Ed., 1995, 34,
3
2039–2041.
2
(
23 J. S. Kingsbury, J. P. A. Harrity, P. J. Bonitatebus and A. H. Hoveyda,
J. Am. Chem. Soc., 1999, 121, 791–799.
24 M. Scholl, S. Ding, C. W. Lee and R. H. Grubbs, Org. Lett., 1999, 1,
1
(
m, 2H), 1.41–1.27 (m, 1H). [a]2 = 60.0 (c = 0.25, CH
0
D
2
Cl
2
).
953–956.
2
5 For reviews see: (a) Applied Homogeneous Catalysis with Organometallic
1
2
(a) I. L. D. Albuquerque, C. Galeffi, C. G. Casinovi and G. B. Marini-
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(
c) A. Sen and T.-W. Li, Inorg. Chem., 1984, 23, 3258–3261; (d)
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26 D. V. McGrath and R. H. Grubbs, Organometallics, 1994, 13, 224–235.
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2
1
002, 124, 13390–13391; (c) B. Schmidt, Eur. J. Org. Chem., 2004,
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8 Selected reviews: (a) R. H. Grubbs, Tetrahedron, 2004, 60, 7117–7140;
b) S. J. Connon and S. Blechert, Angew. Chem., 2003, 115, 1944–1968,
Angew. Chem., Int. Ed., 2003, 42, 1900–1923.
2
3
4
5
(
29 (a) G. D. Cuny, J. Cao, A. Sidhu and J. R. Hauske, Tetrahedron, 1999,
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6
7
R. Stragies and S. Blechert, Synlett, 1998, 169–170.
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31 N. Bettach, Y. LeBigot, Z. Mouloungui, M. Delmas and A. Gaset,
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1
970 | Chem. Commun., 2006, 1968–1970
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