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I. Paterson, C. A. Luckhurst / Tetrahedron Letters 44 (2003) 3749–3754
10. 11 was generated from the corresponding methyl oxazole
by deprotonation with lithium diethylamide (−78°C,
THF) then quenching with TMSCl: Evans, D. A.; Cee, V.
J.; Smith, T. E.; Santiago, K. J. Org. Lett. 1999, 1, 87.
11. De Mico, A.; Margarita, R.; Parlanti, L.; Vescovi, A.;
Piancatelli, G. J. Org. Chem. 1997, 62, 6974.
1455 (m), 1430 (w), 1376 (m), 1362 (m), 1347 (w), 1316
(w), 1256 (m); H NMR (500 MHz, CDCl3) lH 7.49 (1H,
1
s, H30), 7.47 (1H, s, H17), 7.35–7.26 (5H, m, PhH6 ), 6.67
(1H, ddd, J=15.7, 8.1, 6.6 Hz, H20), 6.32 (1H, d, J=16.0
Hz, H19), 6.18 (1H, s, H28), 4.77 (1H, br s, H51a), 4.74
(1H, br s, H51b), 4.61 (1H, dd, J=11.7, 2.4 Hz, H15), 4.54
(2H, ABq, J=12.1 Hz, la=4.58, lb=4.50, PhCH6 2O),
12. Dossetter, A. G.; Jamison, T. F.; Jacobsen, E. N. Angew.
4.02 (1H, app sextet, J=4.7 Hz, H9), 3.96 (1H, m, H5),
3.92 (1H, m, H11), 3.54–3.51 (2H, m, H4a and H22),
3.45–3.40 (3H, m, H4b, H24 and H26), 2.75 (1H, dd,
J=14.5, 11.9 Hz, H14a), 2.60–2.57 (3H, m, H14b, H21a and
Chem., Int. Ed. Engl. 1999, 38, 2398.
13. Mikami, K.; Matsumoto, S.; Ishida, A.; Takamuku, S.;
Suenobu, T.; Fukuzumi, S. J. Am. Chem. Soc. 1995, 117,
11134.
H
12a), 2.44 (3H, s, Me32), 2.42–2.38 (2H, m, H12b and
14. The absolute configuration was determined by Mosher
ester derivatisation of the equatorial alcohol 19. This also
enabled quantification of the enantiomeric excess, which
was corroborated by chiral HPLC (Daicel AD column)
analysis of 17 and comparison with ent-17 made using
the enantiomeric Jacobsen catalyst.
15. Evans, D. A.; Kozlowski, M. C.; Murry, J. A.; Burgey,
C. S.; Campos, K. R.; Connell, B. T.; Staples, R. J. J.
Am. Chem. Soc. 1999, 121, 669.
H8a), 2.32–2.28 (2H, m, H6a and H21b), 2.23 (1H, ddd,
J=14.5, 9.2, 5.4 Hz, H10a), 2.12 (1H, dd, J=13.2, 7.5 Hz,
H6b), 2.02 (1H, dd, J=13.6, 5.4 Hz, H8b), 1.91 (3H, s,
Me48), 1.78 (1H, m, H23), 1.73 (1H, m, H25), 1.63 (1H,
obsc m, H10b), 0.98 (3H, d, J=6.8 Hz, Me50), 0.91 (9H, s,
SiC(CH3)3), 0.75 (3H, d, J=6.5 Hz, Me49), 0.06 (3H, s,
SiCH3), 0.05 (3H, s, SiCH3); 13C NMR (100.6 MHz,
CDCl3) lC 206.0, 161.5, 160.6, 141.2, 140.9, 138.2, 138.1,
137.8, 137.1, 135.5, 134.4, 128.4, 127.6, 127.5, 118.6,
118.0, 110.9, 88.8, 77.7, 77.2, 74.3, 73.3, 71.8, 71.2, 70.8,
68.9, 47.0, 46.3, 39.3, 39.2, 38.9, 36.5, 36.4, 34.8, 25.8,
18.1, 14.3, 13.9, 13.8, 5.9, −4.1, −4.8; HRMS (+ESI) calcd
for C46H64N2O8SiNa (MNa+) 823.4330 found 823.4324.
19. After submission of this manuscript the Pattenden and
Williams groups disclosed their completed total syntheses
of phorboxazole A, see: Gonza´lez, M. A.; Pattenden, G.
Angew. Chem., Int. Ed. 2003, 42, 1255. Williams, D. R.;
Kiryanov, A. A.; Emde, U.; Clark, M. P.; Berliner, M.
A.; Reeves, J. T. Angew. Chem., Int. Ed. 2003, 42, 1258.
16. Dahanukar, V. H.; Rychnovsky, S. D. J. Org. Chem.
1996, 61, 8317.
17. Lewis, M. D.; Cha, J. K.; Kishi, Y. J. Am. Chem. Soc.
1982, 104, 4976.
18. All new compounds gave spectroscopic data in agreement
with the structures indicated and stereochemical proof
was obtained via Mosher ester and NOE analysis where
applicable. Compound 3 was isolated after HPLC purifi-
cation as an oil: [h]D20=+27.7 (c 0.13, CHCl3); IR (CHCl3
solution) 2985 (w), 2957 (m), 2928 (m), 2854 (m), 1717 (s,
CꢀO), 1660 (w), 1600 (m), 1586 (w), 1492 (w), 1467 (w),