名称:
Total Synthesis of Granditropone, Grandirubrine, Imerubrine, and Isoimerubrine
摘要:
Concise total syntheses of the naturally occurring tropoloisoquinolines grandirubrine (1), imerubrine (2), and isoimerubrine (3) are detailed. The regioselective total synthesis of grandirubrine (1) is based on the [4 + 2] cycloaddition reaction of the alpha-pyrone 44 with the cyclopropenone ketal 18. Subsequent retro-Diels-Alder loss of CO2, norcaradiene rearrangement to the cycloheptatrienone ketal, and ketal hydrolysis provided the tropone 7 (granditropone). Regioselective hydroxylation of granditropone (NH2NH2; KOH) provided grandirubrine (1) and O-methylation of 1 provided both imerubrine (2) and isoimerubrine (3).