Figure 7.

(a) Chiral amine C afforded an excess of the HH regioisomer, whereas bulkier chiral amine F led predominantly to the HT regioisomer. The HH regioisomer possesses a free terminus capable of elongation, whereas HT has both termini capped, hindering further elongation. The degree of stereochemical induction was in all cases gauged using the dissymmetry factor g_abs, which is proportional to ee, with a g_abs of 2.54 × 10^–3 corresponding to 100% ee (Supporting Information Section 7.2). (b) Plot of g_abs against the monomer-to-chiral-inducer ratio (proportional to polymer length, Figure S24) for the HH system where all precursors were combined simultaneously. A decrease in induction was observed at an A/C ratio above 2. (c) g_abs plotted against the rate of addition of A (18 equiv) and Cu^I (9 equiv) to (S)-C (1 equiv); slower rates of addition favored a greater degree of induction. (d) Plot of g_abs against the ratio of monomer A to bulky chiral inducer (R)-F where all precursors were combined simultaneously. Two regimes were observed: (i) where an increase in the A/F ratio favored a greater degree of chiral induction and (ii) where a further increase in the A/F ratio reduced the degree of chiral induction, as a greater proportion of polymer chains initiate from achiral A as opposed to chiral F. (e) Plot of g_abs (440 nm) against the rate of addition of A (18 equiv) and Cu^I (9 equiv) to F (1 equiv), affording an HT polymer, again showing two regimes: (i) where an increase in rate of addition disfavored termination through chain-capping by free F, affording an increase in induction; (ii) more rapid addition reduced enantioenrichment because proportionally fewer polymer chains nucleated from chiral F residues and more initiation took place via the racemic standard polymerization pathway (Figure 1).