Partialsynthese der Grandidone A, 7‐Epi‐A, B, 7‐Epi‐B, C, D und 7‐Epi‐D aus 14‐Hydroxytaxodion

Partial Synthesis of Grandidones A, 7‐Epi‐A, B, 7‐Epi‐B, C, D and 7‐Epi‐D, from 14‐Hydroxytaxodione Oxydative addition of coleon U ( 6 ) to 14‐hydroxytaxodione ( 5 ) in the presence of Fétizon 's reagent mainly leads to grandidone A ( 1a ) and 7‐epigrandidone A ( 1b ) ( ca. 15:1), whereas coleon V ( 7 ) and 5 under the same conditions yield grandidone B ( 2a ) and 7‐epigrandidone B ( 2b ) ( ca. 3:1). Dimerization of 14‐hydroxytaxodione ( 5 ) gives grandidone C ( 3 ; ca. 40%), grandidone D ( 4a ; ca. 50%) and 7‐epigrandidone D ( 4b ; ca. 10%). All these compounds obtained by partial synthesis are in every respect identical with the natural products, thus establishing their absolute configurations. The thermal transformation of grandidone C ( 3 ) to grandidone D ( 4a )/7‐epigrandidone D ( 4b ) and interconversions of 4a and 4b were achieved. Oxydative addition of coleon U ( 6 ) to 14‐hydroxytaxodione ( 5 ) in the presence of Fétizon 's reagent mainly leads to grandidone A ( 1a ) and 7‐epigrandidone A ( 1b ) ( ca. 15:1), whereas coleon V ( 7 ) and 5 under the same conditions yield grandidone B ( 2a ) and 7‐epigrandidone B ( 2b ) ( ca. 3:1). Dimerization of 14‐hydroxytaxodione ( 5 ) gives grandidone C ( 3 ; ca. 40%), grandidone D ( 4a ; ca. 50%) and 7‐epigrandidone D ( 4b ; ca. 10%). All these compounds obtained by partial synthesis are in every respect identical with the natural products, thus establishing their absolute configurations. The thermal transformation of grandidone C ( 3 ) to grandidone D ( 4a )/7‐epigrandidone D ( 4b ) and interconversions of 4a and 4b were achieved. Oxydative addition of coleon U ( 6 ) to 14‐hydroxytaxodione ( 5 ) in the presence of Fétizon 's reagent mainly leads to grandidone A ( 1a ) and 7‐epigrandidone A ( 1b ) ( ca. 15:1), whereas coleon V ( 7 ) and 5 under the same conditions yield grandidone B ( 2a ) and 7‐epigrandidone B ( 2b ) ( ca. 3:1). Dimerization of 14‐hydroxytaxodione ( 5 ) gives grandidone C ( 3 ; ca. 40%), grandidone D ( 4a ; ca. 50%) and 7‐epigrandidone D ( 4b ; ca. 10%). All these compounds obtained by partial synthesis are in every respect identical with the natural products, thus establishing their absolute configurations. The thermal transformation of grandidone C ( 3 ) to grandidone D ( 4a )/7‐epigrandidone D ( 4b ) and interconversions of 4a and 4b were achieved. Oxydative addition of coleon U ( 6 ) to 14‐hydroxytaxodione ( 5 ) in the presence of Fétizon 's reagent mainly leads to grandidone A ( 1a ) and 7‐epigrandidone A ( 1b ) ( ca. 15:1), whereas coleon V ( 7 ) and 5 under the same conditions yield grandidone B ( 2a ) and 7‐epigrandidone B ( 2b ) ( ca. 3:1). Dimerization of 14‐hydroxytaxodione ( 5 ) gives grandidone C ( 3 ; ca. 40%), grandidone D ( 4a ; ca. 50%) and 7‐epigrandidone D ( 4b ; ca. 10%). All these compounds obtained by partial synthesis are in every respect identical with the natural products, thus establishing their absolute configurations. The thermal transformation of grandidone C ( 3 ) to grandidone D ( 4a )/7‐epigrandidone D ( 4b ) and interconversions of 4a and 4b were achieved.