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Three open chains precursors of a simplified model of a 14-membered cyclopeptide alkaloid, the ansapeptide , 1-oxa-2-isopropyl-3-amino-4,7-dioxo-5,8-diaza-6-benzyl[10] paracyclophane, were prepared, but ring closure failed. A discussion of this failure led to an attempted ring closure of ansapeptides having structures close to the former, but with larger rings. Three 15-, 17- and 18-membered ansapeptides were effectively synthesized. This result confirmed the existence of a special stretching in the 14-membered ring, explaining the difficulties in cyclisation.
- Rocchiccioli,Jarreau,Pais
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p. 2917 - 2926
(2007/10/08)
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