derivatives have the potential to undergo cycloadditionreactions with double and triple bonds, e.g., 1,3‐dipolar cycloadditions or DielsAlder reactions. We here report on the scope and limitations of cycloadditionreactions of 2‐alkylquinolizinium‐1‐olates 9 with electron‐poor acetylene derivatives. As main products of the reaction, 5‐oxopyrrolo[2,1,5‐de]quinolizines (=‘[2.3.3]cyclazin‐5‐ones’) 19 were
Competing Regiodirecting Effects of Ester and Aryl Groups in [3+3] Cyclocondensations of 1,3-Bis(trimethylsilyloxy)-1,3-butadienes: Regioselective Synthesis of 3-Hydroxyphthalates and 2-Hydroxyterephthalates
es are prepared by regioselective chelation-controlled cyclization of 1,3-bis(silyloxy)-1,3-butadienes with 4-silyloxy-2-oxo-3-butenoates derived from acetylpyruvates. The employment of silylated benzoylpyruvates instead of acetylpyruvates results in a regioselectivity change and the formation of 6-aryl-2-hydroxyterephthalates. The cyclization of 1,3-bis(silyloxy)-1,3-butadienes with 4-ethoxy-2-oxo-3-butenoates