Metal-free [2+2]-photocycloaddition of unactivated alkenes enabled by continuous flow processing

Area of Science:

• Organic Chemistry
• Photochemistry
• Synthetic Methodology

Background:

• The Kochi-Salomon reaction provides a pathway to cyclobutanes.
• Developing metal-free synthetic routes is crucial for sustainability.
• Continuous flow chemistry offers advantages in reaction control and scalability.

Purpose of the Study:

• To develop a novel, metal-free continuous flow method for synthesizing bicyclic cyclobutanes.
• To utilize unactivated alkenes as starting materials.
• To adapt photochemical reactions for efficient flow synthesis.

Main Methods:

• A continuous flow reactor setup was employed.
• Photochemical activation was achieved using a filtered mercury lamp.
• Acetone was used as a UV light-absorbing co-solvent.

Main Results:

• Successful generation of bicyclic cyclobutanes from unactivated alkenes.
• Demonstration of a metal-free synthetic pathway.
• The method proved efficient under continuous flow conditions.

Conclusions:

• The developed continuous flow approach offers a sustainable and efficient method for bicyclic cyclobutane synthesis.
• The use of a filtered mercury lamp and acetone is key to the reaction's success.
• This metal-free strategy has potential for broader applications in organic synthesis.