Question
An abbreviated mechanistic description for DCC-medicated amide bond formation is illustrated as path A. An alternative pathway for this process has been proposed as well, illustrated in Path B. In this alternative pathway, a second molecule of acid 1 out-competes the amine 4 for the pivotal activated acyl derivative 3, leading to a transient symmetrical anhydride 7 (with discharge of 6). In path B, anhydride 7 then is the active electrophile that reacts with amine 4 to give observed amide product 5 with regeneration of one molecule of acid 1. Assuming that only path A were operational, what amide product(s) would you anticipate if the reaction were run with 1 equiv. of the achiral acid 8, 1 equiv, of the racemic amine 9, and a limiting amount (0.1 equiv.) of the chiral 10? Select one: Chiral amide 11a only. Chiral amide 11b only. An equal mix of 11a and 11b (= racemic mix). An unequal mix of 11 a and 11b.
Explanation / Answer
since it is following path b
we will get the racemic mixture 11a and 11b with 1:1 ratio
so option C is correct answer
in path B though you are using chiral diimide derivative from ths it is foming th eanhydride
after this amine is reacting with this amide