Using hyperpolarised NMR and DFT to rationalise the unexpected hydrogenation of quinazoline to 3,4-dihydroquinazoline

Josh E. Richards, Alexander J.J. Hooper, Oliver W. Bayfield, Martin C.R. Cockett*, Gordon J. Dear, A. Jonathon Holmes, Richard O. John, Ryan E. Mewis, Natalie Pridmore, Andy D. Roberts, Adrian C. Whitwood, Simon B. Duckett

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


PHIP and SABRE hyperpolarized NMR methods are used to follow the unexpected metal-catalysed hydrogenation of quinazoline (Qu) to 3,4-dihydroquinazoline as the sole product. A solution of [IrCl(IMes)(COD)] in dichloromethane reacts with H2 and Qu to form [IrCl(H)2(IMes)(Qu)2] (2). The addition of methanol then results in its conversion to [Ir(H)2(IMes)(Qu)3]Cl (3) which catalyses the hydrogenation reaction. Density functional theory calculations are used to rationalise a proposed outer sphere mechanism in which (3) converts to [IrCl(H)2(H2)(IMes)(Qu)2]Cl (4) and neutral [Ir(H)3(IMes)(Qu)2] (6), both of which are involved in the formation of 3,4-dihydroquinazoline via the stepwise transfer of H+ and H, with H2 identified as the reductant. Successive ligand exchange in 3 results in the production of thermodynamically stable [Ir(H)2(IMes)(3,4-dihydroquinazoline)3]Cl (5).

Original languageEnglish
Pages (from-to)10375-10378
Number of pages4
JournalChemical Communications
Issue number73
Early online date28 Aug 2018
Publication statusPublished - 18 Sept 2018

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© The Royal Society of Chemistry 2018.

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