Table 2.

Substrate scope

^aConditions A: TMSOTf (3 equiv.) and EtMgBr (3 equiv.); conditions B: BF₃⋅Et₂O (1.5 equiv) and EtMgBr (1.5 equiv.)

^bReported yields are for isolated products

^cDetermined by chiral HPLC

^dThe absolute configurations of products were determined on the basis of single-crystal X-ray diffraction analysis of compound 2a′ (see Supplementary Information)

^eEtMgBr diluted in toluene and added dropwise over 2 h

^fee of corresponding alcohol 2c' after deprotection

^g5 mol% of catalyst used

^hee of the corresponding ether 10

ⁱSmall amount of unreacted substrate (≤9%) is not separable from product by chromatography, yields are calculated by purity of product in the mixed fraction by ¹H NMR