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. Author manuscript; available in PMC: 2012 Jul 31.
Published in final edited form as: J Am Chem Soc. 2008 Dec 3;130(48):16295–16309. doi: 10.1021/ja804659n

Scheme 7.

Scheme 7

Synthesis of the ABCD-aldehyde 3. Reagents and conditions: a) 7 (1.6 equiv), LDA, THF, −78 °C; then 8 (1.0 equiv); b) Dess-Martin periodinane, pyr, CH2Cl2, 92% (2 steps); c) Na/Hg (5%), NaH2PO4, THF/MeOH, −10 °C, 92%; d) TBAF, THF, −20 °C (workup); e) PPTS, CH2Cl2, 0 °C (83%, 2 steps); f) TBAF, AcOH, DMF, 86%; g) SO3·Pyr, DMSO, i-Pr2NEt, CH2Cl2, −30 °C, 91%. See ref31 for abbreviations.