Hydrofunctionalisation of an Aromatic Triphosphabenzene.

Area of Science:

• Organometallic Chemistry
• Heterocyclic Chemistry
• Computational Chemistry

Background:

• 2,4,6-tri-tert-butyl-1,3,5-triphosphabenzene is an aromatic heterocycle with unique reactivity.
• Reactions involving E-H bond activation are crucial in synthetic chemistry.
• Understanding reaction mechanisms and stereochemical outcomes is key to controlling chemical synthesis.

Purpose of the Study:

• To investigate the reactivity of 2,4,6-tri-tert-butyl-1,3,5-triphosphabenzene with main group element hydrides (silanes, germanes, stannanes).
• To elucidate the reaction mechanism, specifically the 1,4-addition pathway.
• To understand the factors controlling the diastereomeric ratios of the bicyclic products formed.

Main Methods:

• Experimental reaction studies of the triphosphabenzene with various silanes, germanes, and stannanes.
• Analysis of bicyclic product formation and determination of diastereomeric ratios.
• Density Functional Theory (DFT) calculations to model the reaction pathway and energetics.

Main Results:

• The triphosphabenzene undergoes facile 1,4-addition reactions with silanes, germanes, and stannanes, with reactivity correlating to E-H bond strength.
• Bicyclic products are formed with diastereomeric ratios that are dependent on the specific substrate used.
• DFT calculations confirm activation of the E-H bond across the 1,4-C/P axis and explain the observed stereochemical preferences.

Conclusions:

• The reaction provides a versatile route to novel bicyclic compounds incorporating phosphorus and other main group elements.
• The study highlights the influence of electronic and steric factors on the stereochemical outcome of the addition reaction.
• DFT calculations offer valuable insights into the mechanistic details and predictive power for similar reactions.