Unexpected One-pot Formation of the 1-6a,8a-epiminotricyclopenta[,,][8]annulene System from Cyclopentanone, Ammonia and Dimethyl Fumarate. Synthesis of Highly Strained Polycyclic Nitroxide and EPR Study

Overview

Journal Beilstein J Org Chem

Specialty Chemistry

Date 2019 Dec 7

PMID 31807201

Authors

Sergey A Dobrynin

Igor A Kirilyuk

Yuri V Gatilov

Andrey A Kuzhelev

Olesya A Krumkacheva

Matvey V Fedin

Michael K Bowman

Elena G Bagryanskaya

Affiliations

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Abstract

The unexpected formation of a highly strained polycyclic amine was observed in a one-pot synthesis from cyclopentanone, dimethyl fumarate and ammonium acetate. This multistep reaction includes 1,3-dipolar cycloaddition of dimethyl fumarate to the cyclic azomethine ylide formed in situ from cyclopentanone and ammonia. The polycyclic amine product was easily converted into a sterically shielded polycyclic nitroxide. The EPR spectra and spin relaxation behavior of the nitroxide were studied in solution. The spin relaxation seems well suited for the use as a biological spin label and are comparable with those of cyclic nitroxides with two spirocyclic moieties adjacent to the N-O group.

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