Scheme 10.
Completion of the Total Synthesis of 4.a
aReagents and Conditions: a) LDA, THF, −78 °C, then PhSeBr; b) mCPBA, CH2Cl2, −78 °C, then Et3N, then warm to rt., 89% (2 steps); c) TBAF, THF, 40 °C, 83%; d) LDA, THF, −78 °C, then PhSeBr; e) mCPBA, CH2Cl2, −78 °C, then Et3N, then warm to rt., 55% (2 steps).