- Stereoselective synthesis of polysubstituted tetrahydrofurans by radical cyclization of epoxides using a transition-metal radical source. Application to the total synthesis of (±)-methylenolactocin and (±)-protolichesterinic acid
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Radical cyclization reactions of substituted α-(prop-2-ynyloxy) epoxides using bis(cyclopentadienyl)-titanium(III) chloride as the radical source resulted in polysubstituted tetrahydrofurans. Titanium(III) species were prepared in situ from commercially available titanocene dichloride and zinc dust in tetrahydrofuran. Upon radical cyclization, 2-aryl epoxides 3a-e afforded only trans products 4a-e whereas the 2-alkyl epoxides 3f-h formed a mixture of isomeric products 4f-h in a ratio of 5:1. Some of the aryl tetrahydrofuran derivatives have already been used for the synthesis of bioactive furofuran lignans. 2-Pentyl-3-(hydroxymethyl)-4- methylenetetrahydrofuran (4f) and 2-tridecyl-3-(hydroxymethyl)-4- methylenetetrahydrofuran (4g) have been transformed to two antitumor antibiotics (±)-methylenolactocin (1f) and (±)-protolichesterinic acid (1g), respectively, in good overall yield.
- Mandal,Maiti,Roy
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- PHARMACEUTICAL COMPOSITIONS COMPRISING LIGNANS AND THEIR DERIVATIVES FOR TREATING HYPERPLASTIC DISEASES
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The present invention relates to a pharmaceutical composition comprising specific compounds which may be obtained from Leontopodium alpinum Cass. (Edelweiss). A preferred compound is leoligin (=(2S,3R,4R)-4-(3,4-dimethoxybenzyl) -2-(3,4-dimethoxyphenyl)tetrahydrofuran-3-yl]methyl(2Z)-2-methylbut-2-enoat]). Corresponding means and methods in respect of medical uses of the compounds are described. The present invention also provides a medical device comprising, containing or having been contacted with the compound. The compounds provided herein may particularly be used in the treatment of hyperplastic diseases, in particular intimal hyperplasia, e.g. stenosis, restenosis, atherosclerosis and the like. Also envisaged herein is the use of these compounds in the treatment of proliferative diseases, such as leukemia, prostate cancer and lung cancer.
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