Pyrrolidine-camphor derivative

Imidazole and its derivatives continued to play an important role in asymmetric processes. Optically active pyrroloimidazoles 26 were prepared by the cycloaddition of homochiral imidazolium ylides with activated alkenes <96TL1707>. This reaction was used in the enantioselective preparation of pyrrolidines <96TL1711>. A review of the use of chiral imidazolidines in asymmetric synthesis was published <96PAC531> and the preparation and use of a new camphor-derived imidazolidinone-type auxiliary 27 was reported < 6TL4565> <96TL6931>. 

In 2013 Chen et al. reported the direct organocatalytic Michael addition of cyclic ketones to l,l-bis(phenylsulfonyl)ethylene using the camphor-derived pyrrolidine 25." The desired Michael adducts were obtained in high chemical yields and very good stereoselectivities (Scheme 11.21). 

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