We then considered the effects of loading and multiple additions on yield and er compared to our base reaction (Table , entry 1). Attempting to spread out the overall addition of 15 mol% iron over 3 days led to minimally increased yield and still eroded er (Table , entries 2-3). Further iron multiple addition and loading studies are detailed in the SI. While increasing the loading of the chiral thiol, we noticed a maximum yield of 40% (Table , entry 1 vs entries 4-7). Similarly, er is slightly enhanced upon increasing to 20 mol% thiol but remains unchanged up to 50 mol%. However, increasing to stoichiometric loading of chiral thiol eroded the er, potentially due to the thiol catalyst aggregating in solution. On efficiency grounds, the chiral thiol is among the more expensive components of this reaction system, and we determined that the modest increase in yield and er observed with 50 mol% thiol did not justify the increased loading. Spreading out the addition of overall 10 mol% chiral thiol