A Boratafulvene.

Area of Science:

• Organometallic Chemistry
• Heterocyclic Chemistry

Background:

• Boroles are a reactive class of heterocyclic compounds.
• Understanding their electronic properties and reactivity is crucial for synthetic applications.

Purpose of the Study:

• To synthesize and characterize novel B-alkyl boroles and their deprotonated forms.
• To investigate the electronic implications of alkyl substitution on borole structures.
• To explore the reactivity of the newly formed 5-boratafulvene anion.

Main Methods:

• Deprotonation of B-methyl boroles to form 5-boratafulvene anions.
• Structural characterization using X-ray crystallography.
• Electronic structure analysis using Density Functional Theory (DFT) calculations.
• Reactions with electrophiles (e.g., Me3SnCl) and in bora-Wittig-type reactions.

Main Results:

• Successful synthesis and structural authentication of free B-alkyl boroles.
• Generation of the first 5-boratafulvene anion, an isomer of boratabenzene.
• DFT calculations confirmed the acidic character of the exocyclic B-CH3 group and the anti-aromatic nature of the borole moiety.
• The non-aromatic boratafulvene anion acts as a C-centered nucleophile, reacting with Me3SnCl to form a stannylmethyl borole and regenerating anti-aromaticity.
• Boratafulvene demonstrated utility as a methylene transfer reagent in bora-Wittig-type reactions.

Conclusions:

• Boratafulvenes represent a new class of nucleophilic synthons for boroles.
• This discovery opens novel synthetic pathways for accessing highly reactive borole heterocycles.
• The study highlights the unique electronic properties and versatile reactivity of boratafulvenes.