“…To explore the reaction mechanism, reactions of diastereomerically pure ( R , S )‐ and ( S , S )‐ 8a were performed under the optimized reaction conditions outlined in Table , entry 13 (Scheme ). As a result, although the rate of the reaction involving ( R , S )‐ 8a was higher than that of ( S , S )‐ 8a , the same diastereomeric mixture of ( R , S )‐ 10a was obtained with almost equally high diastereoselectivity, irrespective of the stereochemistry of the starting material.…”