Electrochemical synthesis of saturated nitrogen-containing heterocycles

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Milton, Joseph Patrick ORCID: https://orcid.org/0000-0002-3907-5136 (2021). Electrochemical synthesis of saturated nitrogen-containing heterocycles. University of Birmingham. M.Sc.

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Abstract

The use of electrochemistry in synthesis is a relatively unexplored area of organic chemistry that is currently experiencing a resurgence of interest, with many expansive review articles[1, 2] and guides[3-5] published in recent years. The launch of the ElectraSyn 2.0 has further accelerated this interest, which is a convenient piece of equipment for organic electrochemistry for newcomers and experts alike. The
formation of saturated nitrogen-containing heterocycles via electrochemical routes has received little attention and only the groups of Moeller[6-8] and Yoshida[9, 10] have reported the synthesis of pyrrolidine rings in the 21st century so far.
Following the interests of our group in developing new methods for the synthesis of nitrogen-containing heterocycles, herein is reported the diastereoselective synthesis of pyrrolidine-derivatives using an electrochemical process which offers a greener alternative to the previously published iodocyclisation method for the formation of azetidines and pyrrolidines.[11, 12] The formation of α-aryl 2-((phenylselanyl)methyl)-1-tosylpyrrolidines was achieved in a straightforward one-pot manner, with the starting material subjected to the desired electrochemical conditions as inputted into an ElectraSyn 2.0. Diastereoselectivity is controlled via the addition or omission of a base, resulting in an approximate 4:1 trans:cis diastereomeric ratio with a base and 1:4 trans:cis ratio without. Isolation of the major product was achieved via column chromatography and/or preparative thin layer chromatography with a silica stationary phase, which afforded 40 – 79% yield for the major diastereoisomer. In total, 14 pyrrolidine-derivatives, of which, 12 are novel compounds, were synthesised with this methodology in scales ranging from 0.1 to 1.0 mmol. Preliminary attempts to use the same methodology for the formation of azetidines resulted in no cyclisation.

Type of Work:

Thesis (Masters by Research > M.Sc.)

Award Type:

Masters by Research > M.Sc.

Supervisor(s):