Formal syntheses of (−)-isoretronecanol, (+)-laburnine, and a concise enantioselective synthesis of (+)-turneforcidine

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The synthesis of functionalized pyroglutamates 15 and 16 could be achieved by the application of recently developed diastereodivergent asymmetric Michael addition reaction of iminoglycinate 7 to ethyl γ-silyloxycrotonate with >98:<2 diastereoselectivity followed by hydrolysis and lactamization. Formal syntheses of (−)-isoretronecanol and (+)-laburnine as well as a concise enantioselective synthesis of (+)-turneforcidine could be achieved from functionalized pyroglutamates 15 or 16.

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We thank the Ministry of Science and Technology, Taiwan for financial support (MOST 106-2113-M-007-003).

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Correspondence to Biing-Jiun Uang.

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This manuscript is dedicated to Professor Samuel J. Danishefsky for his outstanding achievements in the area of total synthesis of complex natural products and his dedication to chemical education

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Formal Syntheses of (-)-Isoretronecanol, (+)-Laburnine, and A Concise Enantioselective Synthesis of (+)-Turneforcidine

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