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. Author manuscript; available in PMC: 2008 Aug 6.
Published in final edited form as: Nat Prod Rep. 2008 Apr 14;25(4):719–737. doi: 10.1039/b706296f

Scheme 26.

Scheme 26

Tan’s branching pathways which yield stereochemically and substitutionally diverse polyketide-like molecules. Reagents and conditions: (1) Cp2TiCl2, iBuMgBr, Et2O, 0 °C → rt, 81-86%, >88 : 12 Z:E; (2) Red-Al, Et2O, 0 °C → rt, 99%, >98 : 2 E:Z; (3) m-CPBA, NaHCO3, CH2Cl2, 0 °C → rt (R = H) or −4 °C (R = Me), 91-99%, d.r. >90 : 10; (4) diethyl tartrate (matched enantiomer), Ti(OiPr)4, tBuOOH, 4 Å sieves, CH2Cl2, −20 °C, (R = H) or −20 °C, (R = Me), 85-93%, d.r. 94 : 6; (5) (i) nBuLi, Me3Al, 1,2-dichloroethane, 0 °C→ rt; (ii) NaIO4, MeCN–H2O, 0 °C→ rt, 68-69% (over 2 steps); (6) Dess–Martin periodinane, CH2Cl2, 0 °C→ rt, 85-100%; (7) SmI2, THF, −90→ −78 °C, 65-98%; (8) NaBH(OAc)3, AcOH, MeCN, −20 °C, 87-95%, d.r. >93 : 7; (9) Et2BOMe, NaBH4.