- Application of Electro-Oxidative α-Cyanation of Aza-Rings to the Synthesis of Gephyrotoxin 223AB
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Six and five-membered cyclic α-cyanoamines have been prepared efficiently from N-benzylpiperidine and N-benzylpyrrolidine.These α-cyanoamines were successfully used in the synthesis of gephyrotoxin 223AB.
- Yang, Teng-Kuei,Yeh, Shun-Tsai,Lay, Yen-Yuan
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p. 1711 - 1716
(2007/10/02)
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- General Entry to the 3,5-Disubstituted Indolizidine Class of Dendrobatid Alkaloids. Total Syntheses of Both Enantiomers of Indolizidines 195B, 223AB, 239AB, and 239CD from a Common Chiral Synthon
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A general protocol for the total syntheses of both enantiomers of dendrobatid alkaloids, indolizidines 195B, 223AB, 239AB, and 239CD, belonging to the 3,5-disubstituted indolizidine subclass is described, in which 3,4-dideoxy-D-threo-hexitol (8) has been used as single and common chiral synthon.The syntheses of the (+)- and (-)-enantiomers of these alkaloids begin with (S,S)- and (R,R)-1,2:5,6-diepoxyhexanes (7), respectively, both of which were derived from 8 in three steps and are carried out by way of pyrrolidine formation via the cyclic sulfates leading to the(2R,5R)- and (2S,5S)-trans-2,5-dialkylated pyrrolidines, which were converted to the (+)- and (-)-enantiomers, respectively, of the title indolizidine alkaloids.These syntheses involve the first chiral preparations of indolizidines 239AB, 239CD both in natural (-)- and unnatural (+)-enantiomeric forms, which confirm the absolute configurations of natural 239AB and 239CD as 3R,5S,8aR and 3R,5R,8aR, respectively.
- Machinaga, Nobuo,Kibayashi, Chihiro
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p. 5178 - 5189
(2007/10/02)
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- Rearrangement of Isoxazoline-5-spiro Derivatives. 5. Diastereofacial Selectivity in the Cycloaddition of Substituted Five-Membered Cyclic Nitrones and Methylenecyclopropanes. Srereoselective Synthesis of 3,5-Substituted Indolizidinones
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Substituted five-membered cyclic nitrones 1-3 cycloadd to substituted methylenecyclopropanes 4 and 5 with high diasrereofacial selectivity, through anti-anti transition states, to produce regioisomeric hexahydrospirocyclopropane-1,2'(and 3')-pyrrolo1.2-
- Cordero, Franca M.,Brandi, Alberto,Querci, Cecilia,Goti, Andrea,Sarlo, Francesco De,Guarna, Antonio
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p. 1762 - 1767
(2007/10/02)
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- A Short Total Synthesis of (+/-)-Gephyrotoxin-223AB
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(+/-)-Gephyrotoxin-223AB has been synthesized from 2-carbomethoxycyclopentanone in nine steps by a route utilizing the stereoselective homolytic cyclization of an alkenyl-substituted N-chloropiperidine.
- Broka, Chris A.,Eng, Kan K.
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p. 5043 - 5045
(2007/10/02)
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- Indolizine Alkaloid Synthesis. Preparation of the Pharaoh Ant Trail Pheromone and Gephyrotoxin 223 Stereoisomers
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A stereoselective entry into the 3,5-dialkylindolizidine alkaloid skeleton proceeding via N1-C2 vicinal annulation of a 1,4-dibromoalkane onto a pyrroline system is described.
- Macdonald, Timothy L.
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p. 193 - 194
(2007/10/02)
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