Asymmetric synthesis auxiliary controlled, general

Upon was the use of chiral auxiliaries as counter ions of the carboxylate examples in (38a) and (39a). The authors conclude that the ionic chiral auxiliary approach is a viable general method for asymmetric synthesis. The irradiation of the biphenyl ketoamide (40) at 340 nm affords the two products (41) and (42) via the conventional Norrish Type II hydrogen abstraction process. When the reaction is carried out in the presence of an antibody microenvironment the reaction follows a different route and yields the tetrahy-dropyrazine derivative (43). The authors reason that there is interplay between conformational control and chemical catalysis that results in this high specificity. 

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