Non-chelation control in allylations of α-oxy ketones using group-14 allylatranes.

Stereoselective nucleophilic additions to α-substituted carbonyl compounds are a crucial area of contemporary research in organic chemistry. Of the various advancements in π-facial selectivity in addition reactions of carbonyl compounds, the (polar) Felkin-Anh model and the chelation model are well recognized for accurately explaining the selectivity of the allylic products. For reactions that involve α-oxy carbonyl groups - known for their broad applications in natural-product synthesis and as effective building blocks in organic synthesis - the stereoselective reaction typically follows the chelation model, favoring syn-selective addition. In contrast to the well-established syn-selective additions of α-oxy carbonyls, anti-selective additions through a non-chelation pathway remain largely unexplored. In this study, we present the anti-selective allylation of α-oxy ketones using allylatranes that feature a highly coordinated group-14-element center. These atranes demonstrate high nucleophilicity and low chelating ability due to their transannular interactions and rigid framework, facilitating anti-selective allylations. A combined experimental and theoretical approach has been used to highlight the unique electronic properties of these atranes. This method is applicable to a wide variety of substrates, producing anti-1,2-diols with a homoallylic moiety in high yield and excellent diastereoselectivity compared to traditional methods.