Controlled Synthesis of C/D‐Ring Components of Phycobilin Derivatives Bearing a Photoreactive Group at D‐Ring.

C/D-Ring components of phycobilin derivatives bearing a photoreactive group at D-ring were regioselectively synthesized by applying our original synthetic reactions such as acid-catalyzed rearrangement of 2-tosyl group of 3,4-disubstituted 2-tosylpyrroles to 5-position, regioselective preparation of 3,4-disubstituted 5-tosylpyrrolinones, and their Wittig-type new coupling reaction with 2-formyl pyrrole.