Porphyrins, reaction with pyrazine

Scheme 3 DA reaction of porphyrin Id with pyrazine o-quinodimethane derivative.

Olefinic pyrazines like 108 were shown to react with QH in the superacid TfOH to give anti-Markovnikov addition products like 109 <050L2505>. The orientation observed is presumed to be due to the multiply charged heterocycle adjacent to the olefin. Pyrazine o-quinodimethanes underwent Diels-Alder condensation with meso-tetraarylporphyrins to give new jt-extended porphyrins <05TL2189>. A one-pot formation of polycyclic - and -lactones like 111 was developed using the reaction of pyridine and pyrazine (110) with bis(trimethylsilyl)ketene acetals. Many of them were characterized by X-ray <05EJO3724>. 

---