Cyclobutadienes via an Organocascade
Access to Cyclobutadienes via an Organocatalytic Dienamine–Iminium–Allenamine Cascade Approach.
Org. Lett. 2017;
19 October 2017 (online)
The Wang group reports an organocatalytic [2+2] cycloaddition between α,β-unsaturated aldehydes and ynals. This reaction is catalyzed by secondary amines and generates cyclo-butadienes in high yields under mild conditions.
The authors suggest that the reaction follows a dienamine–iminium–allenamine cascade sequence furnishing cyclobutadienes as products. Typically high temperatures are required for the synthesis of cyclobutadienes. This method requires only room temperature, hence overcoming a limitation of previous methods.