Transposición de Wagner-Meerwein de rasteviol

Abstract

The tricyclic sesquiterpene (1R,3R,4S,5S,7S,8S,9S,10R,11R)-7,8-diangeloyloxylongipinan-1,9-diol, or rasteviol (10), underwent multiple Wagner-Meerwein molecular rearrangements and several hydride shifts when treated with Et2O•BF3 to generate the seven new compounds (1R,3R,4S,5R,7S,8S,9S,10R,11S)-7,8-diangeloyloxy-1,9-epoxyjiquilpane (11), (1R,3R,4S,5R,7R,8S,9S,11S)-8-angeloyloxy-1,7-epoxyzamor-10(14)-ene (14), (2S,3R,4R,5R,6R,7R,8S,9S,10S)-7,8-diangeloyloxy-6,9-epoxyjanitziane (17), (4R,5R,7S,8S,9S,10S,11S)-7,8-diangeloyloxy-9-hydroxyjiquilp-3(15)-ene (19), (2S,3S,5R,7S,8R,10S,11R)-7,8-diangeloyloxyiratzian-9-one (21), (2S,3S,5R,10S,11R)-8-angeloyloxyiratzi-7-en-9-one (25), and (4R,5R,7S,8R,9S,10S,11S)-7,9-diangeloyloxy-8-hidroxyjiquilp-3(15)-eno (26) of which 11, 14, 17, and 21 possess new hydrocarbon skeletons. Their structures were determined by 1D and 2D NMR in combination with single crystal X-ray diffraction analyses of derivatives 13, 18, 23, and 24, which allowed confirmation of their absolute configurations by means of the Flack and Hooft parameters. In addition, some reaction mechanism information was gained from deuterium labeling experiments.

El sesquiterpeno tricíclico (1R,3R,4S,5S,7S,8S,9S,10R,11R)-7,8-diangeloiloxilongipinan-1,9-diol, o rasteviol (10), se sometió a múltiples reordenamientos moleculares Wagner-Meerwein y algunos desplazamientos de hidruro cuando se trató con Et2O•BF3, lo generó siete nuevos compuestos (1R,3R,4S,5R,7S,8S,9S,10R,11S)-7,8-diangeloiloxi-1,9-epoxijiquilpano (11), (1R,3R,4S,5R,7R,8S,9S,11S)-8-angeloiloxi-1,7-epoxizamor-10(14)-eno (14), (2S,3R,4R,5R,6R,7R,8S,9S,10S)-7,8-diangeloiloxi-6,9-epoxijanitziano (17), (4R,5R,7S,8S,9S,10S,11S)-7,8-diangeloiloxi-9-hidroxijiquilp-3(15)-eno (19), (2S,3S,5R,7S,8R,10S,11R)-7,8-diangeloiloxiiratzian-9-ona (21), (2S,3S,5R,10S,11R)-8-angeloiloxiiratzi-7-en-9-ona (25), y (4R,5R,7S,8R,9S,10S,11S)-7,9-diangeloiloxi-8-hidroxijiquilp-3(15)-eno (26), de los cuales 11, 14, 17 y 21 poseen nuevos esqueletos hidrocarbonados. Las estructuras fueron determinadas por resonancia magnética nuclear en una y dos dimensiones, en combinación con el análisis por difracción de rayos X de los derivados 13, 18, 23 y 24, lo que permitió la confirmación de sus configuraciones absolutas por medio de los parámetros Flack y Hooft. Adicionalmente el marcaje isotópico proporcionó información sobre los mecanismos de reacción propuestos.