A series of diazinobarrelenes 8–15 engendered with alkyl functionalities at the barrelene skeleton were irradiated with 350 nm light under direct and acetone-sensitized reaction conditions. Under these conditions, all the barrelenes except barrelene 14 afforded semibullvalenes with varying degrees of regioselectivity and product distribution. Dicyanopyrazinobarrelenes 8–10 which furnished semibullvalenes 32–41via the aryl– ...
