Porphyrins participate as dienophiles in Dials-Alder reactions with ortha-q
uinodimethanes or pentacene. They can also behave as dipolarophiles in 1,3-
dipolar cycloadditions with a range of 1,3-dipoles. These two reaction type
s were successfully used to synthesize novel chlorins, bacteriochlorins and
isobacteriochlorins. Copyright (C) 2000 John Wiley & Sons, Ltd.