Synthesis of Functionalised Cyclopropanes from Carboxylic Acids via a Radical Addition–Polar Cyclisation Cascade

  • Bjoern Andreassen

Student thesis: Master's ThesisMaster of Science (MSc)

Abstract

Boronic esters are highly versatile reagents with widespread application in synthetic organic chemistry, due to their ability to be transformed into a variety of functional groups with complete stereocontrol.Consequently, it is unsurprising that a range of methods have been developed to introduce boronic esters in organic compounds. Recent work in the Aggarwal group has shown the utility of radical additions to
vinyl boronic esters for the synthesis of alkyl boronic esters under photoredox conditions.

In this work, the development of an organo-photocatalysed dicarbofunctionalisation reaction via a radical addition-polar cyclisation cascade pathway was developed. The reaction utilises readily available carboxylic acids and vinyl boronic esters which, under photoredox conditions react to form functionalised cyclopropyl boronic esters (Scheme A). The reaction was demonstrated to be amenable to a broad range of carboxylic acids, providing a convenient method for the synthesis of structurally diverse cyclopropyl boronic in yields of 55-99% (Scheme B).

Furthermore, a regioselective Pd-catalysed hydroboration of alkynes was developed for the efficient and scalable synthesis of 1,1-disubstituted vinyl boronic esters (Scheme C), allowing easy access to substrates for the organo-photocatalysed dicarbofunctionalisation reaction and other purposes.
Date of Award19 Mar 2019
Original languageEnglish
Awarding Institution
  • The University of Bristol
SupervisorVarinder K Aggarwal (Supervisor)

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