Enantioselective Pd-Catalyzed Allylic Alkylation Reactions of Dihydropyrido[1,2-a]indolone Substrates: Efficient Syntheses of (-)-Goniomitine, (+)-Aspidospermidine, and (-)-Quebrachamine

α-Alkylation of Chiral Sulfinimines for Constructing Quaternary Chiral Carbons by Introducing Removable Directing Groups

This study developed a facile and efficient synthetic strategy to construct quaternary chiral centers at the α-position of imines and ketones. High regioselectivity and diastereoselectivity were achieved through the synergetic effect of electron-withdrawing directing groups and N-tert-butyl sulfinamide as chiral auxiliaries. Either of them could be removed under the optimized conditions without any epimerization.

Stereodivergent Synthesis of Pseudotabersonine Alkaloids

An eight-step stereodivergent synthesis of enantiomerically pure (-)-14-epi-pseudotabersonine and (+)-pseudotabersonine has been developed from a common N-tert-butanesulfinyl ketimine key intermediate.

Enantioselective Catalysis Coupled with Stereodivergent Cyclization Strategies Enables Rapid Syntheses of (+)-Limaspermidine and (+)-Kopsihainanine A

Enantioselective Pd-catalyzed allylic alkylations of dihydropyrido[1,2-a]indolone (DHPI) substrates were used to construct the C20-quaternary stereocenters of multiple monoterpene indole alkaloids. Stereodivergent Pictet-Spengler and Bischler-Napieralski cyclization/reduction cascades furnish the cis- and trans-fused azadecalin subunits present in Aspidosperma and Kopsia alkaloids, respectively, en route to highly efficient syntheses of (+)-limaspermidine and (+)-kopsihainanine A.

Pd(0)-Catalysed asymmetric reductive Heck-type cyclization of (Z)-1-iodo-1,6-dienes and enantioselective synthesis of quaternary tetrahydropyridines

The asymmetric reductive Heck reaction of (Z)-1-iodo-1,6-dienes has been developed, which affords quaternary tetrahydropyridines with good to excellent enantioselectivities.

Catalytic Enantioselective and Diastereoselective Allylic Alkylation with Fluoroenolates: Efficient Access to C3-Fluorinated and All-Carbon Quaternary Oxindoles

Synthetically versatile 3,3-disubstituted fluorooxindoles exhibiting vicinal chirality centers were obtained in high yields and with excellent enantio-, diastereo-, and regioselectivity through catalytic asymmetric fluoroenolate alkylation with allylic acetates. The reaction proceeds under mild conditions and can be scaled up without compromising the asymmetric induction. The unique synthetic usefulness of the products is highlighted by the incorporation of additional functionalities and the formation of 3-fluorinated oxindoles exhibiting an array of four adjacent centers of chirality. A new C-F bond functionalization path that provides unprecedented possibilities for the stereoselective generation of a chiral quaternary carbon center in the alkaloid scaffold is introduced.