Ramsay E. Beveridge, Yiwei Hu, Bruce Gregoire
Jun 4, 2020
Citations
0
Influential Citations
4
Citations
Journal
The Journal of organic chemistry
Abstract
The reagent di-tert-butyl ethynylimidodicarbonate is demonstrated as a β-aminoethyl anion synthetic equivalent. It can be used to install ethyleneamine groups by exploiting its terminal alkyne reactivity with common organic electrophiles. Reactions exemplified with this terminal ynimide reagent include additions to imines, aldehydes, ketones, pyridinium salts, Michael acceptors, epoxides, as well as Pd-catalyzed Sonogoshira couplings. Subsequent regioselective [3+2] cycloadditions of the alkynyl-imides (ynimides) generate N,N-di-Boc imide functionalized triazole and isoxazole heterocycles. Reduction of the ynimides with Pd-catalyzed hydrogenation generates ethyleneimides with easily removable N,N-di-Boc-carbamate protecting groups allowing for a flexible ynimide based approach to ethyleneamine installation. The utility of this two-step aminoethylation strategy was demonstrated in the short formal syntheses of pyrrolidinoindoline alkaloids (±)-CPC-1 and (±)-alline. Analogously, the reagent (N,N,N')-tri-Boc 2-ethynylhydrazine, serves as a β-hydrazinoethyl anion synthetic equivalent.