Conformationally constrained β-amino acid derivatives by intramolecular [2 + 2]-photocycloaddition of a tetronic acid amide and subsequent lactone ring opening.
D.; McDonald, R.; West, F. G. Diastereoselective [4+4]-photocycloaddition reactions of pyran-2-ones: rapid access to functionalized 5-8-5 skeletons. Org