Diastereoselective Synthesis of Silyl-Substituted Pyrrolidines.

In this paper, we report the synthesis and structural investigation of enantioenriched methylene isosteres of Hayashi-Jørgensen catalysts, and their application in organocatalysis. -protected pyrrolidines - were prepared in high yields and excellent diastereoselectivity using a new one-pot, four-step synthetic protocol involving: (a) the formation of a silyllithium reagent (), (b) its addition to a diaryl olefin () to generate a silyl-substituted diphenylethyllithium intermediate (), (c) the highly diastereoselective addition of this intermediate to a chiral sulfinimine (), and (d) intramolecular cyclization to the desired products. After -deprotection, the new catalysts were further evaluated in benchmark Michael additions of aliphatic aldehydes to β-nitrostyrene, under various conditions, demonstrating reactivity and stereoselectivity comparable to the Hayashi catalyst. Notably, the trimethylsilyl derivative ()- showed superior enantioselectivity, transferring its stereochemical information with remarkable efficiency (up to 99% ). Structural studies through 2D-NMR and DFT calculations revealed different conformational preferences for the corresponding enamines, providing insight into the observed catalytic performance.