The Synthetic Routes of 9,9-Diphenylfluorene-2-Boronic acid pinacol ester

The synthesis of 9,9-diphenylfluorene-2-boronic acid pinacol ester, popularly referred to as DPFBA, has been a subject of interest in the chemical industry due to its unique properties and applications.
DPFBA is an important building block for the synthesis of boronic acid-based organic compounds and materials, which have numerous applications in various fields such as plastics, pharmaceuticals, and electronics.

The synthesis of DPFBA can be achieved through several routes, each of which has its advantages and disadvantages.
In this article, we will explore some of the most commonly used synthetic routes for DPFBA and discuss their merits and demerits.

Route 1: Boronation of Diphenylfluorene

One of the most commonly used routes for the synthesis of DPFBA involves the boronation of diphenylfluorene, which is a simple and straightforward process.
The starting material diphenylfluorene is treated with an equimolar mixture of boron trifluoride and toluene, which leads to the formation of DPFBA in a quantitative yield.

Advantages:

• The reaction is simple and straightforward, making it an attractive synthetic route.
  
• The use of equimolar amounts of reagents makes the reaction stoichiometrically favorable, leading to high yields.
  

Disadvantages:

• The use of boron trifluoride gas can be hazardous due to its toxicity and corrosive nature.
  
• The reaction requires careful handling and purification to remove any traces of boron trifluoride.
  

Route 2: Pinacol Estification of Boronic Acid

Another commonly used route for the synthesis of DPFBA involves the pinacol estification of boronic acid, which is a well-established synthetic method.
Boronic acid is treated with an alcohol, such as pinanol, in the presence of a strong acid catalyst, such as sulfuric acid, to form the pinacol ester.
The pinacol ester is then treated with an excess of boronic acid and diethyl oxalate to form DPFBA.

Advantages:

• The reaction is relatively mild and can be carried out at room temperature, making it safer and easier compared to other synthetic routes.
  
• The reaction can be easily scaled up, making it a practical synthetic route.
  

Disadvantages:

• The reaction requires careful handling and purification to remove any traces of boronic acid and the strong acid catalyst.
  
• The use of diethyl oxalate can be expensive and may require additional safety precautions due to its toxicity.
  

Route 3: Direct Aldol Condensation

A third route for the synthesis of DPFBA involves the direct aldol condensation of boronic acid derivatives, such as 2-borono-1,3-oxazolidin-3-one, with other boronic acid derivatives.
The reaction involves the condensation of boronic acid derivatives in the presence of a Lewis acid catalyst, such as aluminum chloride, to form DPFBA.

Advantages:

• The reaction is simple and straightforward, making it an attractive synthetic route.
  
• The use of Lewis acid catalysts can lead to high yields and selectivities.
  

Disadvantages:

• The use of Lewis acid catalysts can be expensive and may require additional safety precautions due to their toxicity.
  
• The reaction may require additional purification steps to remove any unwanted byproducts.
  

In conclusion, the synthesis of DPFBA can be achieved through several routes, each with its advantages and disadvantages.
The boronation of diphenylfluorene and the pinacol estification of boronic acid are two commonly used routes that are relatively safe and easy to carry out.
The direct aldol condensation is another route that can lead