Towards a fully conjugated, double-stranded cycle: a mass spectrometric and theoretical study

Area of Science:

• Organic Chemistry
• Mass Spectrometry
• Computational Chemistry

Background:

• Investigating precursors for complex unsaturated molecules is crucial in synthetic chemistry.
• Understanding reaction pathways and potential isomerizations is key to successful synthesis.

Purpose of the Study:

• To evaluate compounds 1 and 5 as potential precursors for the fully unsaturated double-stranded target compound 2.
• To elucidate the formation pathways and stability of compound 2.

Main Methods:

• Collision-induced dissociation experiments using ion cyclotron resonance mass spectrometry.
• Flask-type pyrolyses and subsequent mass spectrometric analysis.
• Computational calculations to assess molecular stability and isomerization.

Main Results:

• Compound 5, but not compound 1, yielded the molecular ion of compound 2 (m/z 932) under investigated conditions.
• Calculations suggest compound 2 may isomerize to a less strained structure with interrupted conjugation.
• Hydrogen shift from alkyl chains into the cycle's perimeter is proposed as the isomerization mechanism.

Conclusions:

• Compound 5 is a viable precursor for the target compound 2.
• The observed behavior suggests an energetically favorable isomerization pathway for compound 2, driven by strain energy reduction.