Pyrrolidinyl–camphor derivatives have been proven to be efficient organocatalysts for enantioselective conjugate addition of ketones to alkylidene malonates, affording high chemical yields (up to 95 %) of the corresponding products with high to excellent levels of diastereoselectivity (up to >99:1 dr) and enantioselectivity (up to 96 % ee) under solvent‐free reaction conditions at ambient temperature.
Practical and convenient synthetic routes have been developed for the synthesis of a new class of pyrrolidinyl-camphor derivatives (7 a-h). These novel compounds were screened as catalysts for the direct Michael addition of symmetrical alpha,alpha-disubstituted aldehydes to beta-nitroalkenes. When this asymmetric transformation was catalyzed by organocatalyst 7 f, the desired Michael adducts were obtained in high chemical yields, with high to excellent stereoselectivities (up to 98:2 diastereomeric ratio (d.r.) and 99 % enantiomeric excess (ee)). The scope of the catalytic system was expanded to encompass various aldehydes and ketones as the donor sources. The synthetic application was demonstrated by the synthesis of a tetrasubstituted-cyclohexane derivative from (S)-citronellal, with high stereoselectivity.
Remarkable reaction rate and excellent enantioselective direct α‐amination of unmodified aldehydes with various azodicarboxylates was catalyzed by pyrrolidinylcamphor organocatalyst 2a (5 mol‐%) to provide the desired aminated products with excellent chemical yields and high to excellent levels of enantioselectivity (up to >99 % ee) at 0 °C in CH2Cl2.
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