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

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))2CLi2(THF)]2 1 reac...

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Published inAngewandte Chemie International Edition Vol. 60; no. 48; pp. 25281 - 25285
Main Authors Xu, Maotong, Wang, Tongtong, Qu, Zheng‐Wang, Grimme, Stefan, Stephan, Douglas W.
Format Journal Article
LanguageEnglish
Published Weinheim Wiley Subscription Services, Inc 22.11.2021
EditionInternational ed. in English
Subjects
Benzene
Carbon monoxide
C−C formation
dilithiomethane
Fossil fuels
hexasubstituted benzene
Hydrocarbons
ketene cyclotrimerization
Lithium
Nitrous oxide
Substitutes
Transition metals
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Summary: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))2CLi2(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 13C labels. The mechanisms of these reactions are detailed via extensive DFT computations. The dianion [(Ph2P(S))2CLi2(THF)]2 1 reacts with CO affording C−C bond formation and Ph2P(S)‐fragment migration. Subsequent reaction with N2O cleaves a P−C bond generating an anionic ketene‐derivative which cyclotrimerizes to give the hexa‐substituted benzene derivative, [Ph2P(S)COLi(THF)2]3 6 regioselectively. The experimental observations are rationalized by a detailed theoretical study of the reaction mechanism by state‐of‐the‐art DFT methods.
Bibliography:These authors contributed equally to this work.
ISSN:1433-7851
1521-3773
DOI:10.1002/anie.202111486