Approach to the total synthesis of chlorothricolide: synthesis of (.+-.)-19

Robert E. IrelandMichael D. Varney. J. Org. Chem. , 1986, 51 (5), pp 635–648. DOI: 10.1021/jo00355a013. Publication Date: March 1986. ACS Legacy Arc...
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J. Org. Chem. 1986,51,635-648 above was treated with 0.5 N NaOH solution (80 mL) and extracted with three 50-mL portions of chloroform. The combined chloroform layer was washed with water (100mL) and dried over (1.11g, 36% Na2S04. Evaporation of the solvent gave (S)-(-)-5 based on the initially used (S)-(-)-5),mp 225-232 "C, [a]2g-107" (e 1.1,chloroform). (S)-(-)-5: 'H NMR (CDClJ 6 1.19 (s,6CHJ, 1.37 (9, 6 CH,), 6.50(d, 2 H, J = 7.9 Hz), 6.92 (t, 2 H, J = 7.0 Hz), 6.96-7.03 (m, 4 H), 7.06-7.14 (dd, 4 H, J = 7.6 and 12.5Hz), 7.33-7.40(m, 2 H), 7.44-7.53 (dd, 2 H, J = 8.6 and 13.1 Hz), 7.61-7.67 (m, 4 H), 7.75-7.84(m, 6 H), 7.97 (d, 2 H, J = 7.0 Hz); 31PNMR (CDC1,) 29.5 ppm; IR (KBr) u 3050 (m), 2950 (s), 2900 (m), 2870 (m), 1598 (m), 1553 (w), 1502 (m), 1462 (m), 1392 (m), 1363 (m), 1302 (w), 1265 (m), 1195 (s), 1133 (m), 1112 (w), 1018 (w), 869 (w), 815 (m), 810 (m), 751 (4,740(m), 693 (w), 683 (w), 650 (m), 607 (s), 581 (w), 568 (w), 557 (m), 522 (m), 489 (m) cm-'; UV (ethanol) ,A, 233 (z 130000),273 (sh, 12000),287 (12000), 300 (sh, lOOOO),316 (sh, 36001,332 (3500)nm. The purification of the antipode (R)-(+)-5,which went to the complex mother liquor of recrystallization of the (S)-(-)-5-(-)-7 was not carried out. Reduction of (S)-(-)-5 into 2,2'-Bis[bis(p-tert -butylpheny1)phosphinyll-1,l'-binaphthyl [p-tert-BuC8H4BINAP] [(S)-(-)-91. To a mixture of (S)-(-)-5 (1.50g, 1.71 mmol) and triethylamine (1.65mL, 1.20 g, 11.9mmol) in xylene (25mL) was added dropwise a solution of trichlorosilane (1.40g, 10.3 mmol) in xylene (5 mL) at 20 "C. After the addition was completed, the mixture was heated with stirring at 100-110 "C for 3 h. Workup mp 263-265 as described above gave 0.75 g (52%) of (S)-(-)-9, "C, [a]24D-83" (c 1.0,benzene). (S)-(-)-9:'H NMR (CDCl,) 6 1.24 (9, 6 CH,), 1.26 (s, 6 CH,), 6.65 (d, 2 H, J = 8.5 Hz), 6.74 (t, with fine splitting, 2 H, J = 7.6 Hz), 6.92-6.98(m, 4 H), 7.06 (d, 4 H, J = 7.9Hz), 7.08-7.16(m, 4 H), 7.20-7.32 (m, 6 H), 7.47 (d, with fine splitting, 2 H, J = 7.0 Hz), 7.78 (d, 2 H, J = 8.2 Hz), 7.87 (d, 2 H, J = 8.2 Hz); 31PNMR (CDC1,) -16.4 ppm; IR (KBr) Y 3050 (w), 2950 (s),2895 (w), 2860 (w), 1596 (w), 1551 (w), 1495 (m), 1461 (m), 1392 (m), 1361 (m), 1307 (w), 1264 (s), 1200 (w), 1082 (s), 1015 (s),946 (w), 865 (w), 825 (s), 815 (s), 776 (w), 745 (s),697 (w), 645 (w), 581 (w), 556 (m), 515 (w),456 (w),cm-'; LRMS (70eV), m / z (% intensity) 846 (M', 0.14),552 (ll),551 (481,550 (loo),549 (M' - (C4H&&)2P, 1.31,298 ((C4H9-C6H4)2P12.3); HRMS (70eV), m / z 846.4464,calcd for CmHMP2846.4482. UV 221 (e 125000),237 (sh, 100000)nm. Anal. Calcd (ethanol) A, for CmHMP2:C, 85.07;H, 7.62. Found: C, 84.95;H, 8.03. X-ray Analysis of the Complex of (S)-(-)-3, (lR)-(-)-6,and

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Acetic Acid. Crystal data for the title complex are given in Table I. Single crystals were grown from a solution of the complex (0.25 g, 0.38 mmol) in a mixture of ethyl acetate (8.5mL) and acetic acid (0.1mL). A suitable crystal was sealed in a thin-walled glass capillary. Diffraction data were collected with graphite-monochromated Cu Ka radiation. Fifty accurately centered reflections in the range 4O0