2,4-Dinitrobenzenesulfonamides: A simple and practical method for the preparation of a variety of secondary amines and diamines

“…6). Subsequent selective methanolysis of the trifluoroacetate 14 gave tertiary alcohol 15, which was treated with 2-mercaptoethanol and 1,8-diazabicyclo [5.4.0]undec-7-ene in acetone to remove 2-nitrobenzenesulfonyl group (28)(29)(30) to yield the corresponding secondary amine. The piperidine ring of the upper part was constructed by intramolecular S N 2 reaction to furnish demethylvinblastine (16).…”

Section: Resultsmentioning

confidence: 99%

Stereocontrolled total synthesis of (+)-vincristine

Kuboyama

Yokoshima

Tokuyama

et al. 2004

Proc. Natl. Acad. Sci. U.S.A.

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An efficient total synthesis of (؉)-vincristine has been accomplished through a stereoselective coupling of demethylvindoline and the eleven-membered carbomethoxyverbanamine presursor. Demethylvindoline was prepared by oxidation of 17-hydroxy-11-methoxytabersonine, followed by regioselective acetylation with mixed anhydride method. Although an initial attempt of coupling by using demethylvindoline formamide was not successful and resulted in recovery of the starting compounds, the reaction using demethylvindoline took place smoothly to furnish the desired bisindole product with the correct stereochemistry at C18. After formation of the piperidine ring by sequential removal of the protective groups and intramolecular nucleophilic cyclization, the total synthesis of vincristine was completed by formylation of N1.

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“…The solvent was concentrated in vacuo, and the product was purified by flash column chromatography using dichloromethane, gradually increase the polarity to 20% methanol in dichloromethane to give the pure compound as amorphous off white powder (rotamers) (0.29 g, 63%). δ H (300 MHz, DMSO-d 6 15. To a mixture of 6-amino-1-hexanol (5.00 g, 42.7 mmol) was added dimethylaminopyridine (5.20 g, 42.7 mmol) in dichloromethane (215 mL) and ethyl trifluoroacetate (10.2 mL, 85.4 mmol).…”

Section: (100%) Ethyl [5-(17-octadiynyl)-uracil]acetic Acidmentioning

confidence: 99%