Azulenylcarbene and naphthylcarbene isomerizations. Falling solid flash vacuum pyrolysis

Area of Science:

• Organic Chemistry
• Reaction Mechanisms
• Computational Chemistry

Background:

• Carbenes are highly reactive intermediates crucial in organic synthesis.
• Azulene derivatives offer unique electronic properties for chemical exploration.
• Flash vacuum pyrolysis (FVP) is a powerful technique for generating and studying unstable species.

Purpose of the Study:

• To investigate the generation and reactivity of 1-azulenylcarbene.
• To elucidate the reaction pathways and mechanisms involved in its decomposition.
• To explore carbene rearrangements and product formation using computational methods.

Main Methods:

• Generation of 1-azulenylcarbene via falling solid flash vacuum pyrolysis (FS-FVP).
• Analysis of reaction products including cyclobuta[de]naphthalene and cyclopenta[cd]indene.
• Density functional theory (DFT) calculations at the B3LYP/6-31G** level to determine reaction mechanisms and activation barriers.

Main Results:

• 1-Azulenylcarbene rearranges to benzofulvenyl-7-carbene and 1-naphthylcarbene.
• Formation of cyclobuta[de]naphthalene, cyclopenta[cd]indene, and benzofulvenallene explained via proposed pathways.
• Evidence for a 2-azulenylcarbene-1-azulenylcarbene rearrangement was observed.
• DFT calculations confirmed low activation barriers (<35 kcal/mol) for observed rearrangements.

Conclusions:

• The study successfully generated and characterized 1-azulenylcarbene.
• Reaction mechanisms involving carbene rearrangements were elucidated and computationally supported.
• FS-FVP combined with DFT provides a robust approach for studying reactive intermediates.