Fig. 3: Substrate scope of S_NAr1.3.

a, S_NAr1.3 is compatible with a variety of different electrophile (left) and nucleophile (right) coupling partners to form diverse products containing all-carbon quaternary stereocentres or nitrogen-containing quaternary stereocentres (23). S_NAr1.3 also promotes C–O bond construction using phenols or activated alcohols as nucleophiles. With the exception of 24, the stereochemistry of the major enantiomer formed in the biotransformations was assigned by analogy to S_NAr1.3-derived (R)-3. The stereochemistry of 24 was assigned on the basis of previously reported chiral HPLC data⁵ (Supplementary Information). The identity of the halide leaving group on the electrophilic coupling partner was selected on the basis of commercial availability, as well as assessment of reactivity and selectivity when several substrates were available. b, 1,1-Diaryl quaternary carbon centres can be accessed using ethyl 2-cyano-2-phenylacetate (29) as the nucleophile. The most enantioselective variant from the evolutionary trajectory, S_NAr1.2, was further engineered to afford a double mutant S_NAr_Ph1.0 with improved selectivity for the production of 30 (Extended Data Fig. 5). Structure showing the six amino acid positions mutated in S_NAr_Ph1.0 mapped onto the structure of BH32.7 (PDB: 7O1D). Mutations are represented as spheres at the C_α. This variant also enables the synthesis of optically enriched 31 and 32, albeit with reduced selectivity. Reactions were performed using 0.5–5.0 mol% enzyme and 10–20 equivalents of nucleophile. Specific conditions for all reactions are presented in Supplementary Tables 1 and 2. Product yields were determined by HPLC analysis by comparison of product peak areas against standard curves of authentic racemic standards. ^aIsolated yield from a preparative-scale reaction using S_NAr1.3 (0.5 mol%) with electrophile 5 to produce optically pure (R)-3 (152 mg). n.d., not determined. Data points shown are averages of triplicate measurements, with error bars representing standard deviation. See Supplementary Data for source data.