Beilstein J. Org. Chem.2026,22, 603–610, doi:10.3762/bjoc.22.46
–N, C–C, and C–X bond formations, carbene insertions, and oxidative transformations. Comparative analysis with ALFABET, a bond dissociation energy (BDE)-based ML model, reveals that hydricity predictions, when combined with steric accessibility, correctly identify the reactive site in eight out of
ten representative reactions, surpassing BDEs in most cases. These findings highlight hydricity as a complementary and, in some cases, superior descriptor for guiding regioselectivity predictions in electron-rich C–H functionalisation. The model is made available at regioselect.org, together with a
host of other reactivity predictors.
Keywords: bond dissociation energy; hydricity; hydride affinity; hydride-transfer reactions; machine learning (ML); quantum chemistry (QM); Introduction
Bond dissociation energies (BDEs) and pKa values for C–H bonds are often used to rationalise and predict the
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Graphical Abstract
Figure 1:
Different cleavage methods for C–H bonds. Heterolytic bond dissociation energy with proton dissocia...
Beilstein J. Org. Chem.2021,17, 2959–2967, doi:10.3762/bjoc.17.205
compared to benzaldehyde (17, 55%). Higher amounts of aromatic aldehydes were required, probably due to the diminished hydricity of their C–H bond and side reactions under photochemical conditions (see Supporting Information File 1, Table S3 for details). Surprisingly, the very bulky trimethylacetaldehyde
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Graphical Abstract
Figure 1:
Redox potentials of representative nitrogenated HAT catalysts and photocatalysts [9-12,21-23].