Stereocontrolled photodimerization with congested 1,8-bis(4'-anilino)naphthalene templates

Area of Science:

• Organic Chemistry
• Supramolecular Chemistry
• Photochemistry

Background:

• Naphthalene derivatives serve as versatile scaffolds in organic synthesis.
• Cofacial arrangements of aromatic systems can template photochemical reactions.
• Stereoselective synthesis of cyclobutane derivatives is crucial for various applications.

Purpose of the Study:

• To synthesize novel 1,8-bis(anilino)naphthalene derivatives as templates.
• To investigate the stereoselective photodimerization of covalently attached cinnamoyl units.
• To develop efficient routes to specific cyclobutane dicarboxylic acids.

Main Methods:

• Suzuki cross-coupling reactions to synthesize naphthalene templates.
• Functional group transformations to prepare reactive intermediates.
• Photochemical [2+2] cycloaddition reactions for cyclobutane formation.
• Acidic hydrolysis and coupling reactions (EDC) for product isolation.

Main Results:

• Synthesis of 1,8-bis(3'-methyl-4'-anilino)naphthalene (16) and 1,8-bis(4'-anilino)naphthalene (21) in high yields.
• Photodimerization proceeded with high yield and exclusive formation of cis,trans,cis-cyclobutane-1,2-dicarboxylic acids.
• β-truxinic acid (10) and cis,trans,cis-3,4-bis(3,4-dimethylphenyl)cyclobutane-1,2-dicarboxylic acid (26) were synthesized in 69% and 60% overall yields, respectively.
• Quantitative recovery of the naphthalene template was achieved in both cases.

Conclusions:

• The developed naphthalene templates effectively promote stereoselective photodimerization.
• This methodology provides an efficient pathway to synthetically valuable cyclobutane derivatives.
• The quantitative recovery of the template highlights the sustainability of the approach.