Dicarboxylic Acid Monoesters in β- and δ-Lactam Synthesis |
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| Authors: | Anna Ananeva Olga Bakulina Dmitry Dar&#x;in Grigory Kantin Mikhail Krasavin |
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| Institution: | 1.Institute of Chemistry, Saint Petersburg State University, 26 Universitetskii Prospect, 198504 Peterhof, Russia; (A.A.); (D.D.); (G.K.);2.Institute of Living Systems, Immanuel Kant Baltic Federal University, 236041 Kaliningrad, Russia |
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| Abstract: | A N-(2-methoxy-2-oxoethyl)-N-(phenylsulfonyl)glycine monomethyl ester of the respective dicarboxylic acid was involved in a reaction with imines promoted by acetic anhydride at an elevated temperature. Instead of the initially expected δ-lactam products of the Castagnoli–Cushman-type reaction, medicinally important 3-amino-2-azetidinones were obtained as the result of cyclization, involving a methylene group adjacent to an acid moiety. In contrast, replacing alcohol residue with hexafluoroisopropyl in the same substrate made another methylene group (adjacent to the ester moiety) more reactive to furnishing the desired δ-lactam in the Castagnoli–Cushman fashion. |
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| Keywords: | beta-lactams delta-lactams regioselectivity imines carboxylic acid activation cyclization |
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