Arynes are valuable molecules in the field of chemistry due to their high reactivity. Using B3LYP/6-31G(d), we investigated potential mechanisms for adding a phosphorus substituent (PR2OTMS) to a benzyne ring. Our results showed a stepwise pathway, with the rate limiting step being the addition of the phosphorus (12.2 kcal/mol) which is then followed by trimethylsilane transfer to the other benzyne carbon.<br/>The aryne distortion model states the more obtuse carbon of the triple bond will be the site of nucleophilic attack. Using M06L/6-311+G(2d,p), we modelled arynes with various phosphorus substituents. Phosphorus substituents containing electronegative atoms were found to produce a larger angle at the terminus furthest from the substituent and phosphorus substituents containing nitrogen were found to produce larger angles at the terminus closest to the substituent.<br/>Our preliminary investigation of a nucleophilic addition of benzyl amine with a phosphonylated benzyne predicted a preferred product in disagreement of the aryne distortion model. Nucleophilic attack at the carbon with the more acute angle had a barrier height of 1.8 kcal/mol lower than the carbon with the more obtuse angle.

Regioselectivity of reactions of phosphonyl arynes

2019 Spring National Meeting

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