Question

Why the product of four membered ring formed by 2+2 cycloaddition will mot revert back on photoradiation?

Answer 1

$\huge\mathbb\red{HEY\:THERE}$

These terms are used in related [4+2] reaction systems even when the functional groups ... So a cycloaddition may require heating to make the reaction "go", but if it is heated too ...

Answer 2

These terms are used in related [4+2] reaction systems even when the functional groups ... So a cycloaddition may require heating to make the reaction "go", but if it is heated too ...