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. Author manuscript; available in PMC: 2012 Dec 23.
Published in final edited form as: Chemistry. 2010 Nov 19;17(3):895–904. doi: 10.1002/chem.201002402

Scheme 4.

Scheme 4

Preparation of 4'-analogues. a Conditions: (a) K2CO3 (5.0 equiv), MeOH, 0 °C, 82%. (b) 6 (1.6 equiv), Ru-1 (0.10 equiv), benzoquinone (0.17 equiv), DCE, 32 °C, 81%. (c) nBuLi (2.8 equiv), HC≡CCH2OTHP (3.0 equiv), THF, −78 to 0 °C, 90%. (d) Ru-2 (2 mol %), HCO2Na (10 equiv), CTAB (0.2 equiv), H2O, 23 °C, 78%. (e) Ac2O (5.0 equiv), pyridine, 23 °C, 93%. (f) PPTS (0.2 equiv), MeOH, 23 °C, 84%; Na2Cr2O7 (1.5 equiv), acetone, H2SO4, 0 to 23 °C, 86%. (g) H2, Lindlar’s catalyst (1 mol %), quinoline (0.10 equiv) EtOH, 23 °C, 68%. (h) 34 (1 equiv), CH2Cl2/TFA (9:1), 23 °C; then 4'-epi-19 (1.2 equiv), HATU (1.2 equiv), iPr2NEt (4.0 equiv), MeCN, 23 °C, 71%. (i) methacrolein (10 equiv), Ru-1 (2 mol %), 23 °C, 62%. (j) Ph3PCH3Br (2.2 equiv), KOtBu (2.2 equiv), THF, 0 °C, 84%. (k) K2CO3 (2.0 equiv), MeOH, 0 °C, 86%. (l) 6 (1.5 equiv), Ru-1 (0.10 equiv), DCE, 35 °C, 34%. (m) CDI (1.5 equiv), CH2Cl2, 23 °C; morpholine (4.1 equiv), 23 °C, 80%. (n) 6 (1.6 equiv), Ru-1 (0.07 equiv), DCE, 42 °C, 44%. CDI: 1,1'-carbonyldiimidazole.