T. Takabatake, K. Fujiwara, Sho Okamoto
Sep 3, 2020
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Influential Citations
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Journal
Tetrahedron Letters
Abstract
Abstract A synthetic route for the common intermediate, methyl 2-formylbenzofuran-7-carboxylate (7a), to efficiently assemble three bioactive benzofurans 4–6 was explored using the artificial intelligence system SYNSUP. Among the routes proposed by SYNSUP, we investigated a three-step synthesis of 7a using methyl 4-ally-3-oxohept-6-enoate (10). A new catalytic reaction was found in which 7a was directly obtained from 10 in a single step with a yield of 24%. It was found that this chemical yield could be increased to 74% when methyl 3-allyl-2-hydroxybenzoate (9a), an intermediate of the above one-pot transformation, was subjected to the catalytic process. In addition, in this catalytic process, 8a (76%) and 11 (77%) were each selectively synthesized from 10 by changing only the solvent. Therefore, we created a novel orthogonal synthesis of methyl 2-methylbenzofuran-7-carboxylate (8a) and methyl 9-oxobicyclo[3.3.1]nona-3,6-diene-1-carboxylate (11). Finally, the total syntheses of bioactive benzofurans 4–6 were completed smoothly using 7a and 8a.