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.