Synthesis of A-23187 and Related Model Compounds

A-23187 is a calcium specific ionophore isolated from Streptomyces chartreusis. Syntheses of model systems containing the 1, 7-dioxaspiro[5.5]undecane ring system and the total synthesis are discussed. Based on results from the total synthesis the absolute configuration of A-23187 is assigned. A new ionophore, X-14547A, was recently discovered which, like A-23187, contains a pyrrole ketone subunit. Kew methodology designed to introduce the pyrrole unit via an N-protected 2-pyrrylcuprate is presented. See PDF of thesis for figure. [6S*-{6α(2S*,3S*),8β(R*),9β,11α}]-5-(Methylamino)-2-[{3,9,11-trimethyl-8- |l-methyl-2-oxo-2-(1H-pyrrol-2-yl)-ethyl |-1,7-dioxaspiro[5.5]undec-2-yl}methyl]-4-benzoxazole-carboxylic acid.