Palladium‐Catalyzed Allylic Alkylation of Aldimine Esters with Vinyl‐Cyclopropanes to Yield α,α‐Disubstituted α‐Amino Acid Derivatives

Regio- and stereoselective syntheses of chiral α-quaternary (Z)-trisubstituted allylic amino acids via synergistic Pd/Cu catalysis

Synergistic palladium/copper catalysis for asymmetric allylic alkylation of vinylethylene carbonates with aldimine esters has been developed for the synthesis of α-quaternary (Z)-trisubstituted allylic amino acids under mild conditions. This methodology features broad substrate compatibilities in yields of up to 87% and up to 94% ee. A facile scale-up and straightforward conversion to 1,2,3,5-tetrasubstituted pyrrole and 1,2,5,6-tetrahydropyridine bearing chiral quaternary carbon centers verifies the synthetic utility of this method.

Palladium-catalyzed stereoselective decarboxylative allylation of azlactones: access to (Z)-trisubstituted allylic amino acid derivatives

A palladium-catalyzed stereoselective decarboxylative allylation of azlactones with vinyl methylene cyclic carbonates affords a series of trisubstituted allylic amino acid derivatives in good yields with an exclusive (Z)-configuration.

Copper/Lewis base cooperatively catalyzed asymmetric allylic alkylation of Morita-Baylis-Hillman carbonates with azomethine ylides

In this paper, an asymmetric allylic alkylation of easily available azomethine ylides with Morita-Baylis-Hillman (MBH) carbonates through a copper (i)/Lewis base cooperative catalysis strategy has been realized. The co-catalyzed asymmetric allylic alkylation provided the corresponding amino acid derivatives in up to 90% yields with up to 99% ee as well as good to excellent regioselectivity.

Donor-Acceptor Bicyclopropyls as 1,6-Zwitterionic Intermediates: Synthesis and Reactions with 4-Phenyl-1,2,4-triazoline-3,5-dione and Terminal Acetylenes

The bicyclopropyl system activated by incorporation of donor and acceptor groups in the presence of Lewis acids was used as a synthetic equivalent of 1,6-zwitterions. Opening of both cyclopropane rings in 2'-aryl-1,1'-bicyclopropyl-2,2-dicarboxylates (D-A bicyclopropyl, ABCDs) in the presence of GaI₃ + Bu₄N⁺GaI₄^- results in 5-iodo-5-arylpent-2-enylmalonates as products of HI formal 1,6-addition to the bicyclopropyl system. The use of GaCl₃ or GaBr₃ as a Lewis acid and terminal aryl or alkyl acetylenes as 1,6-zwitterion interceptors allows the alkyl substituent to be grown to give the corresponding acyclic 7-chloro(bromo)-hepta-2,6-dienylmalonates. The reaction of ABCDs with 4-phenyl-1,2,4-triazoline-3,5-dione (PTAD) catalyzed by Yb(OTf)₃ also results in the opening of both cyclopropane rings. The reaction products are tetrahydropyridazine derivatives - (7,9-dioxo-1,6,8-triazabicyclo[4.3.0]non-3-en-2-ylmethyl)malonates - containing one more PTAD moiety in the malonyl group.

Palladium-Catalyzed Regio- and Stereoselective Cross-Coupling of Vinylethylene Carbonates with Ketimine Esters to Generate (Z)-Tri- and Tetra-substituted Allylic Amino Acid Derivatives

Herein we report the palladium-catalyzed regio- and stereoselective cross-coupling of vinylethylene carbonates with ketimine esters to construct allylic amino acid scaffolds. This operationally simple protocol furnished (Z)-tri- and tetra-substituted allylic amino acid derivatives in good to excellent yields with distinguished geometric control under mild reaction conditions and proved to be sufficient in large-scale synthesis while retaining excellent reactivity and stereoselectivity, highlighting the practical value of this transformation.