Is 2,3,4,5-tetramethoxybenzoyl chloride a natural product?
The title compound, which was reported to be a constituent of the fruiting body of the fungus Antrodia camphorata, has been synthesized. The reactivity and spectroscopic properties of the synthetic material do not match those of the natural product. There is currently insufficient information for a definitive structural reassignment.
Confirmation of the Revised Structure of Samoquasine A and a Proposed Structural Revision of Cherimoline.
The identity of the natural product samoquasine A has remained obscure since its isolation from custard apple seeds in 2000. One of the proposed structures, benzo[ f]phthalazin-4(3 H)-one, was prepared in two steps by regioselective ortho-lithiation/formylation of N, N-diisopropyl-2-naphthylamide, followed by cyclization with hydrazine, but was shown to be different from the natural product. Perlolidine, another candidate structure, was synthesized by a novel route involving a β-selective Heck reaction of butyl vinyl ether. Both perlolidine and samoquasine A are converted by trimethylsilyldiazomethane into the same N-methyl derivative. In addition, the 13C NMR spectra of perlolidine and another structurally mis-assigned natural product, cherimoline, are almost identical. Thus, both samoquasine A and cherimoline are actually perlolidine.
17O NMR studies of diaryl α‐diketones. The case of 2,2′,4,4′,6,6′‐hexa‐tert‐butylbenzil
Natural abundance 17O NMR spectra of eleven diaryl α‐diketones are reported. An excellent correlation was found between 17O shifts and σp+. Conformations and π character of the intercarbonyl CC bond are discussed.