Structure of an alleged triazetidine

Kerber, Robert C.; Porter, Albert

doi:10.1021/jo01273a079

Cited by 1 publication

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“…The [2 + 2] cycloaddition reaction is always a direct way to synthesize four-membered rings, , through which a series of four-membered rings like cyclobutane (C 4 ), azetidine (C 3 N), oxetane (C 3 O), thietane (C 3 S), dioxetane (C 2 O 2 ), and so forth were produced. − However, when more nitrogen atoms are introduced, the four-membered ring becomes unstable. For example, the diazetidine (C 2 N 2 ) obtained by [2 + 2] photocycloaddition between NN and CC is prone to undergo the metathesis reaction and generate two CN groups after heating .…”

Section: Introductionmentioning

confidence: 99%

Arylazo under Extreme Conditions: [2 + 2] Cycloaddition and Azo Metathesis

et al. 2023

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The four-membered nitrogen ring (N4-ring) is predicted to be a high-energy density moiety and has been the target of chemical synthesis for quite a long time. Here, by compressing the 1:1 co-crystal of trans-azobenzene and trans-perfluoroazobenzene up to ∼40 GPa, the azo groups were restrained closely in parallel in the crystal and underwent two competitive addition reactions. One is [4 + 2] cycloaddition with the azo group as a part of diene and phenyl as dienophile. The other is [2 + 2] cycloaddition between two azo groups, which produced an unprecedented N4-ring structure as evidenced by the metathesis product. The content of the N4-ring structure significantly increases under higher pressure, and we found that it was the external pressure that decreased the kinetic barrier and realized such a high-tensile moiety. Our work shows that high pressure is an alternative synthetic strategy for these high-tensile structures, which can be very effective under the cooperation of crystal engineering.

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