SYNTHESES WITH 5-DIBROMOMETHYL- AND 5-FORMYL-PYRROMETHENES

With many 5,5′-dimethyl- and 5-bromo-5′-methyl-pyrromethenes the sequence CH 3  → CH 2 Br → CH 2 O Me had been possible. With two such pyrromethenes the following new sequences have been developed: (1) CH 3  → CHBr 2  → CH(OMe) 2 or CHO (cf. IIIe and IVe), (2) CH(OMe) 2 , CHO, or CH 2 OMe → Br (cf. IIIf and IVf), (3) (dimethoxy-methyl-)pyrromethene → formyl-dipyrrylmethane (cf. IX and VII). These provide new intermediates for new porphyrin syntheses and alternative or improved routes to established intermediates.