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Exploring new synthetic routes towards cyanamides

Ayres, James 2018. Exploring new synthetic routes towards cyanamides. PhD Thesis, Cardiff University.
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Abstract

This thesis describes the development of new routes towards the synthesis of cyanamides. Cyanamides are present in a range of biologically active compounds and are useful functional groups for the synthesis of many interesting compounds such as guanidines, ureas, isoureas and many varieties of heterocycles. A range of methods for the synthesis of cyanamides exist, however the most common technique is utilising cyanogen bromide and amines. The technique is effective and vast arrays of cyanamides can be accessed in one step. However, cyanogen bromide is highly toxic and poses a significant safety risk. In recent times new methods have been developed to avoid cyanogen bromide, however many of these techniques are operationally complex or use other highly toxic compounds. In this work three new methods for the synthesis of cyanamides have been developed. A new method for cyanamide synthesis using trichloroacetonitrile as a less toxic and safer to handle cyano source has been developed. A range of cyanamides can be formed in an operationally simple one-pot two-step procedure. This technique provides complementary selectivity to cyanogen bromide. It has also been applied to the synthesis of a biologically active PDE4 inhibitor. The one-pot deoxycyanamidation of alcohols has been developed using N-cyano-N-phenyl-p-methylbenzenesulfonamide (NCTS) as a sulfonyl transfer reagent and cyano source accessing a range of tertiary cyanamides. An array of tertiary cyanamides were accessed, including aniline type, which could not be accessed with TCAN. This approach exploits the under-developed desulfonylative (N-S bond cleavage) reactivity pathway of NCTS. A novel cyanamide and allenamide moiety, N-allenyl cyanamides have been synthesised. Utilising the deoxycyanamidation process, propargyl alcohol and a range of sulfonamides could be reacted to access an array of aryl substituted N-allenyl cyanamides. In addition, this moiety was investigated as a novel chemical building block accessing a range of otherwise challenging to access bespoke cyanamides by hydroarylation, hydroamination, [4+2] and [2+2] cycloadditions.

Item Type: Thesis (PhD)
Date Type: Submission
Status: Unpublished
Schools: Chemistry
Subjects: Q Science > QD Chemistry
Date of First Compliant Deposit: 23 November 2018
Last Modified: 26 Nov 2018 13:57
URI: http://orca-mwe.cf.ac.uk/id/eprint/117062

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