Reactions of a Dilithiomethane with CO and N2O: An Avenue to an Anionic Ketene and a Hexafunctionalized Benzene

摘要

Synthesis of value-added products from simple C1 feedstocks is an attractive alternative avenue to traditional fossil fuels. Hexa-substituted benzene derivatives are highly useful molecules but are often challenging to prepare. Herein, we report that the lithium complex [(Ph2P(S))(2)CLi2(THF)](2) 1 reacts with CO lead to C-C bond formation and migration of a Ph2P(S)-fragment affording 2. Subsequent reaction with N2O results in oxidative cleavage of a P-C bond affording [Ph2P(S)OLi(THF)(2)](2) 4 and the anionic ketene-derivative Ph2P(S)CCOLi(THF)(2) 5. Heating 5 prompts cyclotrimerization giving the hexa-substituted benzene derivative [Ph2P(S)CCOLi(THF)(2)](3) 6 regioselectively. This transition metal-free protocol to a hexa-substituted benzene is viable on a gram scale and permits the incorporation of C-13 labels. The mechanisms of these reactions are detailed via extensive DFT computations.