Impact of Catalyst Deuteration on the Reactivity of Chiral Phase‐Transfer Organocatalysts

Abstract

Site‐specifically deuterated organocatalysts were prepared and found to show improved reactivity over the non‐deuterated analogs. Two privileged C2‐symmetric chiral binaphthyl‐modified tetraalkylammonium salts were selected for this study. The stability of these phase‐transfer catalysts was generally improved by site‐specific deuteration, though the degree of improvement was structure dependent. In particular, a large secondary kinetic isotope effect was observed for the tetradeuterated phase‐transfer catalyst. The performance of these deuterated catalysts in the asymmetric catalytic alkylation of amino acid derivatives was better than that of non‐deuterated analogs at low catalyst loadings. The results suggest that catalyst deuteration is a promising strategy for enhancing the stability and performance of organocatalysts.

Enantioselective organocatalytic strategies to access noncanonical α-amino acids

“… 67 Maruoka catalysts can thus be used at low loadings, which can even be improved by applying derivatives deuterated at their benzylic positions. 68 In fact, these catalysts degrade via a Stevens rearrangement, which can be avoided, in part, by using stronger C– 2 H benzylic bonds.…”