Precise Introduction of the -CHnX3-n (X = F, Cl, Br, I) Moiety to Target Molecules by a Radical Strategy: A Theoretical and Experimental Study

Addition of halomethyl radicals to form bioactive molecules has recently become an efficient strategy. The reaction has a bottleneck, however, which is the effective and selective generation of the proper halomethyl (CHnX3-n)-C-center dot radical by combining CHnX4-n with a carbon radical. Understanding the reactivity and selectivity of carbon radicals in the hydrogen atom transfer (HAT) and halogen atom transfer (XAT) reactions of CHnX4-n is key to the development of such an attractive method. With the help of the emerging data-driven strategy, DFT calculations were used to explore various correlations. For selectivity, the relative energy barriers between HAT and XAT reactions (Delta G(H)(double dagger) - Delta G(X)(double dagger)) correlate reasonably well with the three parameters Delta G(H), Delta G(X), and IP, and the correlation studies reveal that the calculated IPinver and the experimental Delta BDE can be used to conveniently predict the selectivity. Predicted selectivities are consistent with experimental determinations. This work not only provides a possibility for selecting carbon radicals with the known or easily obtained physicochemical data but also demonstrates that the informatic workflow such as generating data and identifying correlations has potential applications in mining reaction rules.

Automated summary

The study focuses on the addition of halomethyl radicals to form bioactive molecules, with an emphasis on understanding the reactivity and selectivity of carbon radicals in hydrogen atom transfer and halogen atom transfer reactions. Through the emerging data-driven strategy, correlations were explored, revealing that predicted selectivities align with experimental determinations. This work highlights the potential applications of informatic workflow in mining reaction rules.