Light-Initiated Four-Step Domino-Multicomponent Synthesis of Functionalized Alkylidenecyclobutanes

Area of Science:

• Organic Chemistry
• Photochemistry
• Synthetic Methodology

Background:

• Cyclobutane derivatives are valuable structural motifs in organic chemistry.
• Efficient synthesis of functionalized alkylidenecyclobutanes remains a challenge.

Purpose of the Study:

• To develop a novel domino-multicomponent reaction for synthesizing functionalized E-alkylidenecyclobutanes.
• To establish a consecutive process with distinct photochemical and nonradiative sequences.
• To explore an intramolecular version for accessing fused-bicyclic structures.

Main Methods:

• A four-step domino-multicomponent reaction (domino-MCR) was developed.
• The protocol involves a tandem photochemical [2 + 2]-cycloaddition/Norrish-I/γ-H transfer.
• Subsequent acetal protection and allylic substitution reactions complete the synthesis.

Main Results:

• Functionalized E-alkylidenecyclobutanes were synthesized from readily available precursors.
• A consecutive process with distinct photochemical and nonradiative steps was established.
• An intramolecular variant yielded complex fused-bicyclic alkylidenecyclobutanes.

Conclusions:

• The developed domino-MCR offers an efficient route to functionalized E-alkylidenecyclobutanes.
• The methodology allows for the synthesis of complex fused-bicyclic systems.
• This work expands the synthetic toolbox for cyclobutane derivatives.