Naturally occurring chlorophylls are important substances in the photosynthesis of higher plants. Their asymmetric carbon skeleton structures, the aromatic macrocyclic chromophores and the various active substituted groups attached to the periphery form a class of special natural products. The different chlorophullous degradation products have also been applied as photosensitizers in the area of photodynamic therapy (PDT), dye-sensitized solar cells (DSSCs) and artificial photosynthetic reaction centers. The diverse types of aromatic π-systems, the multi-region active reaction sites and the complicated tautomeric structures of the chlorophyllous macrocyclic molecules form their characteristic chemical properties. The close-relevance of the pyrrol subring with the aza-annulene in chlorophyll and the efficient conjugation of peripheric functional groups with mother cyclic delocalized system lead to that the different rearrangements frequently occur in chlorophyllous chlorins. The reaction scopes involve each pyrrol subring, the bridged meso-position and the combined exocyclic ring. The rearrangements, either including common name reaction or revealing unique transannular rearrangement, adequately reflect the universality in rearranged form and the novelty in reaction process. These special chemical conversions have been efficient approaches for designing and establishing macrocyclic compounds with novel carbon framework and practical application prospect, and are also an important entry point to deeply explore the basic theory, chemical synthesis and applications research of chlorophyll. Therefore, the recent rearrangement reactions about chlorophyllous tetrapyrrol molecules, based on their chemical modifications and structural conversions are reviewed.

Contents 1 Introduction 2 The basic carbon skeleton structures and chemical reactivities of natural products related to chlorophyll 3 Rearrangement reactions of pyrrol subring in chlotophyll derivatives 3.1 Rearrangement reactions of A-Pyrrol subring 3.2 Rearrangement reactions of B-Pyrrol subring 3.3 Rearrangement reactions of C-Pyrrol subring 3.4 Rearrangement reactions of D-Pyrrol subring 4 Rearrangement reactions at meso-position of chlorophyll derivatives 4.1 Rearrangement reaction at 5- and 10-meso-position 4.2 Rearrangement reaction at 5-meso-position and on the exocyclic ring 4.3 Rearrangement reactions at 20-meso-position 5 Conclusion