Synthetic Studies toward Surveying Biologically Active Compounds from Solubility

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Macrocarpals exhibiting interesting biological activities such as inhibitory activity of HIV RTase is a coupling at C11 position of the hydrophobic sesquiterpene aromadendrane skeleton and at the benzylic position of the hydrophilic isopentyl phloroglucinol dialdehyde. Totally, they are water-soluble. The key step of the synthesis is the coupling reaction of a cyclic dienol ether corresponding to the aromadendrane part with a hexasubstituted benzene chromium complex as a chiral benzyl cation equivalent. The reaction proceeded with an extremely high stereoselective manner. The synthetic method developed here would be applicable to various compounds bearing different alkyl group from isobutyl group, and furthermore, demethylation procedure could control the deprotection step.On the way of the total synthesis of macrocarpal C, we found a new radical ipso-substitution reaction of an aromatic methoxy group. This new C-C bond formation reaction would have great possibilities in the filed of synthetic studies. Therefore, the scope and limitations were investigated with model compounds. In this reaction, the distance of the radical and the aromatic ring was found to be crucial. The limitation could be overcome by the chelation control with Sm (II) iodide. Namely, SmIィイD22ィエD2 generates a ketyl radical, and then is chelating intramolecularly to the oxygen atom of the methoxyl group. Therefore, the radical is easily approaching to the aromatic ring, thereby causing C-C bond formation. From these results, it was found that this new reaction takes place by making the radical close to the methoxy group on an aromatic ring.