Question

Question: How can X be prepared from a constitutional isomer by a series of $\left[2+2\right]$cycloaddition reactions? Interest in molecules that contain several cyclobutane rings fused together has been fueled by the discovery of pentacycloanammoxic acid methyl ester, a lipid isolated from the membrane of organelles in the bacterium Candidatus Brocadia anammoxidans. The role of this unusual natural product is as yet unknown.

Short answer

Answer

Step-by-step solution

[2 + 2] cycloaddition reaction

The $\left[2+2\right]$cycloaddition forms two new bonds by breaking the two pi bonds. Therefore, a four-membered ring is obtained as a product. The stereochemistry of the groups in this cycloaddition depends upon the conditions given in the reaction.

• In the thermal condition, a conrotatory thermal reaction occurs, which leads to the change in the stereochemistry.

• In the photochemical condition, a disrotatory thermal reaction occurs, which does not change the stereochemistry.

Explanation

The$\left[2+2\right]$ cycloaddition occurs one by one in the same molecule and forms the corresponding four-cyclic-membered ring.

$\left[2+2\right]$cycloaddition