Elucidation of the kinetic stabilities of carbenoid species by integration of theoretical and experimental studies

Abstract

The flash quench-flow kinetics of short-lived intermediates such as lithium halocarbenoids have revealed precise kinetics even in subsecond-order reactions. Simple quantum calculations dealing with the bond dissociation energies of the...

Flow Chemistry of Metal Carbenoid Species towards Selective Organic Synthesis

“…Hence, the same authors performed ab initio calculations of the dissociation energies of carbon-halogen bonds in lithium carbenoids and compared these values with the experimentally obtained values of the apparent kinetic decomposition rates. 13 Significant positive and linear correlations have been observed for a series of dichloro-, dibromo-, and diiodomethyllithium species, as well as for a series of chloroiodo-, bromoiodo-, and diiodomethyllithium species. Although the detailed mechanistic studies are still ongoing, these findings provide interesting insights into the comprehensive reactivities of the carbenoid species.…”

Synthesis of Deuterated Compounds by Flow Chemistry

“…Very recently, Nagaki achieved incorporation of single deuterium atom by H/D exchange of one of the two identical methylene protons in various dihalomethanes (halogen = Cl, Br, and I) utilizing lithium diisopropylamide (LDA) as a strong base and deuterated methanol as a deuterium source, where the generation of highly unstable lithium carbenoid intermediates and the suppression of their decomposition was successfully controlled under rapid-mixing microflow conditions (Scheme 21). [35] Monodeuterated diiodomethane thus obtained was readily utilized as a synthetic equivalent of C1 carbenoid "CHD" (monodeuteriomethylene) and subjected to downstream transformations involving Simmons-Smith cyclopropanation, S N 2 type cyclization, halogen-lithium exchange, and Mattesontype rearrangement to give diverse molecules bearing isotope labelling at the specific position (Scheme 22).…”