The synthesis of (-)-stemoamide was achieved in 11 steps from 5-acetoxy-N-crotyl pyrrolidinone. A chiral N-acyl thiazolidinethione was employed in a stereoselective addition to a cyclic N-acyl iminium ion to install the required stereochemistry of carbon C9a. This iminium ion addition product was employed in a stereoselective MgBr2-catalyzed anti-aldol reaction to install the required stereochemistry of carbons C8 and C9. The X-ray crystal analysis of (-)-stemoamide confirmed the structure and the stereochemical outcome of these selective reactions.
Brown seaweeds contain bioactive compounds that show anti-tumorigenic effects. These characteristics have been repeatedly observed in the Lessoniaceae family. Egregia menziesii, a member of this family, is distributed in the North Pacific and its properties have been barely studied. We evaluated herein the cytotoxic and anti-proliferative activity of extracts of this seaweed, through toxicity assay in Artemia salina and lymphocytes, and MTT proliferation assay, in Bergmann glia cells, 3T3-L1 and brain cancer cell lines. E. menziesii’s extracts inhibited the spread of all the tested cell lines. The hexane extract showed the highest cytotoxic activity, while the methanol extract was moderately cytotoxic. Interestingly, seaweed extracts displayed a selective inhibition pattern. These results suggest that E. menziesii’s extracts might be good candidates for cancer prevention and the development of novel chemotherapies due to its highest cytotoxicity in transformed cells compare to glia primary cultures.
Resolution of racemic 2,3-dihydro-2-carboxy-6-methoxybenzofuran (2) by recrystallizations of diastereomeric salts prepared with (S)-(-)-alpha-methylbenzylamine and (R)-(+)-alpha-methylbenzylamine gave the starting materials for the four-step total syntheses of (S)-(-)-2,3-dihydro-2-(1-methylethenyl)-6-methoxybenzofuran (1a) and (R)-(+)-2,3-dihydro-2-(1-methylethenyl)-6-methoxybenzofuran (1b). Their absolute configuration was established by chemical correlation.
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