“…Chiral guanidines have been developed as an important type of organocatalyst in numerous asymmetric reactions, particularly the axially chiral guanidine and the C 2 ‐symmetric bicylic guanidines 16. In the past few years, we have developed a series of C 2 ‐symmetric bicyclic‐guanidine‐catalyzed reactions with excellent results, such as the Diels–Alder reaction,17a protonation,17b–d the Mannich reaction,17e decarboxylative reaction,17f the Michael reaction,3j, 14d, e, 17g–i vinylogous amination,17j and amination 17k. Notably, in 2007, we reported a highly enantioselective Michael addition of dithiomalonates to 2‐cyclopentenone catalyzed by bicyclic guanidine ( 1 ) [Scheme , Eq.…”