Pyrazine o-quinodimethane

Furthermore, it was shown that porphyrin Id can also react with a pyrazine o-quinodimethane derivative (... 

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>. 

Pyrazine derivatives have also served as precursors for quinoxalines in acceptable yields under MWI in solvent-free conditions through the reaction of pyrazine o-quinodimethane intermediates with electron-rich dienophiles. Thus, 2,3-bis... 

The Diels-Alder reaction of meso-tetraarylporphyrins with the pyrazine o-quinodimethane mainly affords the oxidized 49a-c instead of the expected chlorin adducts. The bisaddition is site specific, occurring in opposite pyr-rolic rings and leads to 51 and 52. The novel polycyclic 50a-c, 52a, and 52b result from the coupling between the P-fused quinoxaline ring and one adjacent meso-aryl group. In contrast to compounds 49a and 51a, there... 

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