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. Author manuscript; available in PMC: 2013 Jul 1.
Published in final edited form as: European J Org Chem. 2012 Jun 13;2012(22):4130–4139. doi: 10.1002/ejoc.201200286

Scheme 1.

Scheme 1

Attempted synthesis of dihydropyran 4. Reagents and Conditions: a) dimethyl-t-butyl phosphonoacetate (4.4 equiv.), NaH (3.8 equiv.), THF, 23 °C, 17 h, 74%; b) DIBAL-H (8 equiv.), CH2Cl2, −15 °C, 5 min, 91%; c) NaH (10 mol-%), CCl3CN (1.0 equiv.), ether, 23 °C, 1 h, 98%; d) TIPSOTf (1.1 equiv.), CH2Cl2, 23 °C, 12 h, 79% (brsm); e) CeCl3 (5 equiv.), TMSCH2MgCl (5 equiv.), THF, 23 °C, 12 h, 73%; f) DDQ (2 equiv.), Lewis acid, CH2Cl2, −78 °C to 23 °C, 4 h, decomposition.