The first total Synthesis of the 7,7-dimethylaporphinoid, 4,5-didehydroguadiscine (6), originally isolated from the stems and roots of Hornschuchia oblique (Annonaceae), was achieved by the condensation of homopiperonylamine (7) with an alpha,alpha-dimethylphenylacetic acid derivative (8) and subsequent Pschorr reaction of the resulting benzylisoquinoline intermediate (22). The reported C-13 NMR data were partially revised on the basis of the analysis of HMBC spectra measured under different conditions. The melanogenesis inhibitory activity (IC50 = 4.7 mu M) of 6 was 40 times stronger than that of arbutin (174 mu M), which was used as reference standard. Furthermore, 6 was the most potent natural melanogenesis inhibitor Within this class of compounds.
RAJANBABU, T. V.;REDDY, G. S.;FUKUNAGA, TADAMICHI, J. AMER. CHEM. SOC., 1985, 107, N 19, 5473-5483
作者:RAJANBABU, T. V.、REDDY, G. S.、FUKUNAGA, TADAMICHI
DOI:——
日期:——
RAJANBABU, T. V.;CHENARD, B. L.;PETTI, M. A., J. ORG. CHEM., 1986, 51, N 10, 1704-1712
作者:RAJANBABU, T. V.、CHENARD, B. L.、PETTI, M. A.
DOI:——
日期:——
Nucleophilic addition of silyl enol ethers to aromatic nitro compounds: scope and mechanism of reaction
作者:T. V. RajanBabu、G. S. Reddy、Tadamichi Fukunaga
DOI:10.1021/ja00305a024
日期:1985.9
chloride are not displaced in the reaction, suggesting the absence of radical ion intermediates. Dihydroaromatic nitro derivatives can be isolated in some cases, such as anthracene and naphthalene systems which are less prone to rearomatize. The use of silicon reagents in organic synthesis has been ex- panding rapidly in the past few year^,^-^ and versatile methods for carbon-carbon bond formations have been