Volume 53, Issue 48 pp. 13196-13200
Communication

Organocatalytic Asymmetric Mannich Cyclization of Hydroxylactams with Acetals: Total Syntheses of (−)-Epilupinine, (−)-Tashiromine, and (−)-Trachelanthamidine

Dr. Dipankar Koley

Corresponding Author

Dr. Dipankar Koley

Medicinal and process Chemistry Division, CSIR-Central Drug Research Institute, Lucknow, 226031 (India)

Medicinal and process Chemistry Division, CSIR-Central Drug Research Institute, Lucknow, 226031 (India)Search for more papers by this author
Yarkali Krishna

Yarkali Krishna

Medicinal and process Chemistry Division, CSIR-Central Drug Research Institute, Lucknow, 226031 (India)

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Kyatham Srinivas

Kyatham Srinivas

Medicinal and process Chemistry Division, CSIR-Central Drug Research Institute, Lucknow, 226031 (India)

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Afsar Ali Khan

Afsar Ali Khan

Medicinal and process Chemistry Division, CSIR-Central Drug Research Institute, Lucknow, 226031 (India)

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Ruchir Kant

Ruchir Kant

Molecular and Structural Biology Division, CSIR-Central Drug Research Institute, Lucknow, 226031 (India)

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First published: 26 September 2014
Citations: 51

This work was supported by CSIR-GenCODE (BSC0123), New Delhi. We are thankful to SAIF, CSIR-CDRI, for providing the analytical facilities, R. K. Purshottam for assistance with HPLC, Dr. Tejender S. Thakur, Molecular and Structural Biology, CSIR-CDRI for supervising the X-ray data collection and structure determination of the compound 4 m, and the Director of the Centre of Biomedical Research, Lucknow, 226014, (India) for allowing us to measure optical rotations. Y.K., K.S. thank CSIR for SRF. This is CSIR-CDRI communication no 8778.

Graphical Abstract

Double bonanza: The title reaction in the presence of an imidazolidinone-based catalyst furnished N-bridgehead bicyclic alkaloids bearing [3.3.0], [3.4.0], [4.4.0], and [4.5.0] skeletons. By using this protocol, the total syntheses of (−)-epilupinine, (−)-tashiromine, and (−)-trachelanthamidine were achieved.

Abstract

An asymmetric, organocatalytic, one-pot Mannich cyclization between a hydroxylactam and acetal is described to provide fused, bicyclic alkaloids bearing a bridgehead N atom. Both aliphatic and aromatic substrates were used in this transformation to furnish chiral pyrrolizidinone, indolizidinone, and quinolizidinone derivatives in up to 89 % yield and 97 % ee. The total syntheses of (−)-epilupinine, (−)-tashiromine, and (−)-trachelanthamidine also achieved to demonstrate the generality of the process.

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