- Synthesis of (1R,4R)-2,5-diazabicyclo[2.2.1]heptane derivatives by an epimerization-lactamization cascade reaction
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An epimerization-lactamization cascade of functionalized (2S,4R)-4-aminoproline methyl esters is developed and applied in synthesizing (1R,4R)-2,5-diazabicyclo[2.2.1]heptane (DBH) derivatives. (2S,4R)-4-Aminoproline methyl esters are likely to undergo 2-epimerization under basic conditions, followed by an intramolecular aminolysis of the (2R)-epimer to form the bridged lactam intermediates. Key factors identified for this cascade reaction include the electron-withdrawal N-protective group in the substrates and a strong base as the promoter.
- Cui, Benqiang,Yu, Jie,Yu, Fu-Chao,Li, Ya-Min,Chang, Kwen-Jen,Shen, Yuehai
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p. 10386 - 10392
(2015/01/30)
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- Formal syntheses of (-)- and (+)-aphanorphine from (2S,4R)-4-hydroxyproline
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We describe the efficient formal syntheses of both natural (-)-aphanorphine and unnatural (+)-aphanorphine from the same commercially available amino acid, (2S,4R)-4-hydroxyproline. The tricyclic framework was constructed by intramolecular Friedel-Crafts
- Ma, Zhiqiang,Hu, Hanwei,Xiong, Wanting,Zhai, Hongbin
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p. 7523 - 7531
(2008/02/08)
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- A concise formal synthesis of unnatural (+)-aphanorphine from (2S,4R)-4-hydroxyproline
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(-)-Aphanorphine methyl ether was synthesized in ten steps from commercially available (2S,4R)-4-hydroxyproline, featuring the C-2 configuration inversion of an intermediate amide and intramolecular Friedel-Crafts reaction. The present work constitutes a
- Ma, Zhiqiang,Zhai, Hongbin
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p. 161 - 163
(2008/03/13)
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- Stereoselective synthesis of N-phenylsulfonyl substituted spiro-β- lactams
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A stereoselective synthesis of N-phenylsulfonyl substituted spiro-β- lactams obtained from the N-(phenylmethylene)benzenesulfonamide and the ketene valence tautomer of the bicyclic mesoionic compounds derived from 4- hydroxy substituted N-acyl-L-prolines
- Dalla Croce, Piero,La Rosa, Concetta
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p. 1193 - 1199
(2007/10/03)
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- A concise approach to kainoid analogues
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Highly neuroexcitatory kainoid analogues bearing an aryl substituent at C-4 were synthesised by a short and efficient route from trans-L-4-hydroxypyroline.
- Baldwin, Jack E.,Rudolph, Martin
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p. 6163 - 6166
(2007/10/02)
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