Synthesis of 4,6,8‐Trisubstituted Methyl Azulene‐2‐carboxylates

Abstract

Abstract It is shown that sodium (methoxycarbonyl)cyclopentadienide ( 1 ), which is easily accessible from sodium cyclopentadienide and dimethyl carbonate in THF, reacts with 2,4,6‐trisubstituted pyrylium tetrafluoroborates 2a–d in boiling MeOH to afford the corresponding methyl azulene‐2‐carboxylates 4a–d in good yields. The corresponding 1‐carboxylates 3 were not found ( cf. Schemes 1 and 2 ).