E. Boyd et al. / Tetrahedron Letters 47 (2006) 8337–8341
8341
M. F.; Molloy, K. C.; Lister, S.; Gallagher, T. Tetrahedron
Lett. 1988, 29, 1993–1996; (c) Bower, J. F.; Guillaneux,
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tion (5 mL) and was then allowed to warm to room tem-
perature. The solution was diluted with Et2O (5 mL),
then the aqueous phase separated and extracted with
Et2O (5 mL), the organic extracts combined, washed
with brine (5 mL) and dried (MgSO4). The solvent was
removed in vacuo and the resultant orange oil was puri-
fied (flash silica, 5% EtOAc in petrol 40/60 eluent),
affording 8 as a clear oil (0.133 g, 64%), [a]D = +25.7
(c 0.028, EtOH). 1H NMR, d (ppm): (300 MHz, CDCl3)
7.45–7.35 (15H, m, Ar); 4.77 (2H, apparent t,
J = 11.5 Hz, CH2Ar); 4.69 (2H, apparent t, J =
11.5 Hz, CH2Ar); 4.60 (2H, s, CH2Ar); 4.20 (1H, d,
J = 5.0 Hz, H-3); 4.16 (1H, m, H-5); 4.04 (1H, dd,
J = 7.0, 5.0 Hz, H-4); 3.82 (2H, m, C-6 CH2); 0.35
(9H, s, 3 SiMe3); 13C NMR, d (ppm): (75 MHz, CDCl3)
157.8; 138.3, 138.0; 128.5; 128.4; 128.2; 128.0; 127.9;
127.8; 127.6; 127.5; 120.0; 78.6; 76.8; 74.2; 73.5; 73.0;
72.1; 66.3; À1.6; IR, mmax (cmÀ1): (TF) 3063(w);
3031(w); 2953(w); 2899(w); 2866(w); 1730(w); 1496(w);
1454(m); 1364(w); 1250(m); 1156(m); 1087(s); 1074(s);
1027(m); 846(s); 736(m); 697(s); MS: (CI, NH3,
C30H35O4Si35Cl, MW = 522) 540 ([M+NH4]+, 56%);
522 (M+, 9%); 450 ([MÀSiMe3]+, 19%); 415
([MÀOBn]+, 83%); MM: (CI, C30H35NO4Si35Cl,
[M+NH4]+) requires 540.2327; found 540.2327.
11. For the use of a chlorine substituent as a temporay
activating group in the functionalization of indoles see:
Comins, D. L.; Killpack, M. O. Tetrahedron Lett. 1989,
30, 4337–4340.
12. Schlosser, M.; Schaub, B.; Spahic, B.; Sleiter, G. Helv.
Chim. Acta. 1973, 2166–2171.
´
13. Lebouc, A.; Delaunay, J.; Riobe, O. Synthesis 1979, 610–
613.
14. Eastham, S. A.; Herbert, J.; Painter, J. E.; Patel, P.;
Quayle, P. Synlett 1998, 61–63; Hallett, M. R.; Painter, J.
E.; Quayle, P.; Ricketts, D.; Patel, P. Tetrahedron Lett.
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15. The reaction between silyl enol ethers and SO2Cl2 has been
documented, see: (a) Olah, G. A.; Ohannesian, L.;
Arvanaghi, M.; Prakash, G. K. S. J. Org. Chem. 1984,
49, 2032–2034; for the chlorination of pyrones see: (b)
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16. For the preparation and characterization of 2a and 3a: (a)
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2b and 3b: (b) Igarashi, K.; Honma, T.; Imagawa, T. J.
Org. Chem. 1970, 35, 610–616, Stereochemical assign-
ments for 2c, 3c and 4 are made by analogy and with the
aid of spectroscopic data available for the analogous
benzyl ethers described in Ref. 16a.
Acknowledgements
17. The isolation of chloride 5a, as a by-product, has been
documented previously: Boullanger, P.; Marmet, D.;
Descotes, G. Tetrahedron 1979, 35, 163–167.
We thank the EPSRC, Avecia and Syngenta for support
of this programme of research.
18. (a) For previous peparations of 5b see: Adamson, J.;
Foster, A. B. Carb. Res. 1969, 10, 517–523; (b) Francisco,
´
C. G.; Gonzalez, C. C.; Kennedy, A. R.; Paz, N. R.;
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