Cleavage of Olefins Forming Carbon–Nitrogen Bonds

Keywords

olefins - ozonolysis - [3+2] cycloaddition - triazadienium cation

Significance

Given their key role as industrial feedstock materials, methods for the functionalization of olefins are of critical importance to generate a diverse array of building blocks for use in the preparation of pharmaceuticals, agrochemicals and functional materials. Ozonolysis is a fundamental synthetic process, which mediates cleavage of an olefin to form two corresponding C = O bonds, and is widely exploited in synthesis with alternative approaches to achieve this transformation also reported. The current report describes the development of an aza-version of ozonolysis (termed triazenolysis) in which cleavage is achieved through initial cycloaddition of a triazadienium cation to the alkene to form an intermediate salt 3, which upon treatment under reductive conditions spontaneously decomposes to create two new C–N bonds.

 

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Comment

Key to the success of the reaction development was identification of suitable conditions to promote the decomposition of the dihydrotriazolium salt 3, which forms in quantitative yield when the oxidized triene 2 reacts with norbornene. Various reductants were tried with only ether solvents shown to be successful, leading to the hypothesis that BH₃ was being formed and subsequently stabilized in the reaction medium. This led to the development of optimal conditions with the in situ generation of BH₃ through the reaction of NaBH₄ and I₂. Numerous olefins were studied under the optimal conditions with the selectivity of the reaction (N–N vs C–C bond cleavage) shown to depend on not only the structure of the substrate but also the nature of the triazene employed.

 

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Publication History

Article published online:
23 June 2025