Reduction of halocarbons to hydrocarbons by NADH models and NADH

Abstract

The reduction of halocarbons by NADH models and NADH under ambient conditions is reported as a new type of reactivity pointing towards a hitherto unknown disruptive pathway for NADH/NADPH-dependent processes. The reaction was studied with the omnipresent pesticide DDT, the inhalation anesthetic halothane, and several simple halocarbons. The halide–hydride exchange represents a biochemical equivalent for the reduction of halocarbons by traditional synthetic reagents like silanes (R3Si–H) and stannanes (R3Sn–H). High precision thermochemical calculations (CBS-QB3) reveal the carbon–hydrogen bond dissociation energy of NADH (70.8 kcal·mol−1) to be lower than that of stannane (SnH4: 78.1 kcal·mol−1), approaching that of the elusive plumbane (PbH4: 68.9 kcal·mol−1). The ready synthetic accessibility of NADH models, their low carbon–hydrogen bond dissociation energy, and their dehalogenation activity in the presence of air and moisture recommend these compounds as substitutes for the air-sensitive or toxic metal hydrides currently employed in synthesis.