To a solution of Example 5, E2 (1.0 eq.) in THF (0.1 M solution) at −78° C. was added a solution of n-BuLi (1.3 eq.) in hexane. The solution was stirred for 30 min and then a solution of 6-(2-ethyl-1,3-dioxolan-2-yl)-N-methoxy-N-methylhexanamide (1.5 eq.) in THF was slowly added. The reaction mixture was stirred for 1 hr at −78° C. and then 1 hr at RT. Then water was added and the aqueous phase was extracted with EtOAc. The combined organic extracts were dried (MgSO4) and the solvent was removed under reduced pressure. The crude product was used without purification in the next step. MS (ES) C30H42N2O4Si requires: 523, found: 524 (M+H)+.
