Challenges in the Highly Selective [3 + 1]-Cycloaddition of an Enoldiazoacetamide to Form a Donor–Acceptor Cis-Cyclobutenecarboxamide

Date
2021-06-09
Authors
Joyasawal, Sipak
Ma, Donghui
Doyle, Michael P.
Journal Title
Journal ISSN
Volume Title
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Abstract

A substituted donor–acceptor cyclobutenecarboxamide is synthesized with modest enantiocontrol through a chiral copper(I) complex catalyzed [3 + 1]-cycloaddition reaction of α-acyl diphenylsulfur ylides with 3-siloxy-2-diazo-3-butenamides. With a methyl substituent on the 4- position of the 3-butenamide, the cis-vicinal-3,4-disubstituted cyclobutenecarboxamide is formed with >20:1 diastereocontrol. Donor-acceptor 3-methyl-2-siloxycyclopropenecarboxamide is rapidly formed from the reactant enoldiazoamide and undergoes catalytic ring opening to give only the Z-γ-substituted metallo-enolcarbene. Elimination from 3-siloxy-2-diazo-3-pentenamide to form the conjugated 3-siloxy-2,4-pentadienamide is competitive but minimized at low temperature.

Description
Keywords
donor-acceptor cyclobutenecarboxamide, [3 + 1]-cycloaddition reaction, 3-siloxy-2-diazo3-butenamides, Z-γ-substituted metallo-enolcarbene, box ligands, copper(I)
Citation
Molecules 26 (12): 3520 (2021)
Department
Chemistry