Heavy Metal-Free Fischer-Tropsch Type Reaction: Sequential Homologation of Alkylborane Using a Combination of CO and Hydrides as Methylene Source
Authors Andreas Phanopoulos, Shrinwantu Pal, Takafumi Kawakami and Kyoko Nozaki
Abstract Carbon homologationreactions occur within the well-known Fischer–Tropsch process, usually mediated by transition metal catalysts at high temperature. Here we report the low-temperature, heavy-metal-freehomologation of a carbon chain usingCO as a C1-source showing for the first time that transition-metal catalysts are not required for Fischer–Tropsch-type reactivity. Reaction of an alkylborane in the presence of either LiHBEt3 or LiAlH4 resulted in multiple CO insertion/reduction events to afford elongated chains by more than two methylene (−CH2−) units, affording aldehyde products upon oxidative aqueous workup. Theoretical and experimental mechanistic studies indicate that the boron terminus is responsible for CO incorporation as well as sequential hydride delivery leading to reduction of acylborane intermediates to alkylboranes.