Synthesis of anti- and syn- diol epoxides of trans-4,5-dihydro-4,5-dihydroxybenzo[j]fluoranthene and trans-9,10-dihydro-9,10-dihydroxybenzo[j]fluoranthene
摘要:
The preparation of diastereomeric anti- and syn-epoxides of benzo[j]fluoranthene (BjF) 4,5- and 9,10-dihydrodiols is described. The anti-diol epoxides were prepared from the corresponding dihydrodiols by epoxidation with m-chloroperoxybenzoic acid. The isomeric syn-diol epoxides were synthesized by base-catalyzed (Amberlyte IRA-400) cyclization of the bromo triol derivatives which in turn were prepared from the respective dihydrodiols by treatment with N-bromoacetamide in aqueous THF. New methods were employed for the preparation of 4- and 10-hydroxyBjF which are precursors for BjF-4,5-dihydrodiol and BjF-9,10-dihydrodiol. Cyclodehydration of 2-[2-(9-methoxy-11-hydroxybenzo[a]fluoren-11-yl)ethyl]-1,3-dioxane in polyphosphoric acid afforded 4-methoxyBjF (from which the phenol is readily prepared) in 87% yield. Reaction of 1-(4-methoxyphenyl)-acenaphthylene with ethyl diazoacetate is catalyzed by copper-bronze and gave a mixture of diastereomeric cyclopropane carboxylates. These were converted to the corresponding aldehydes by diisobutylaluminum hydride reduction and Swern oxidation followed by cyclodehydration with polyphosphoric acid to give 10-methoxyBjF in 91% yield. It had previously been reported that reduction of BjF-4,5-quinone to BjF-4,5-dihydrodiol occurs in low yield due to overreduction to a mixture of tetrahydro diols and triols. We now report that complexation of the quinone with silver nitrate followed by reduction with potassium borohydride in the presence of oxygen affords BjF-4,5-dihydrodiol in 91% yield.
Synthesis of anti- and syn- diol epoxides of trans-4,5-dihydro-4,5-dihydroxybenzo[j]fluoranthene and trans-9,10-dihydro-9,10-dihydroxybenzo[j]fluoranthene
摘要:
The preparation of diastereomeric anti- and syn-epoxides of benzo[j]fluoranthene (BjF) 4,5- and 9,10-dihydrodiols is described. The anti-diol epoxides were prepared from the corresponding dihydrodiols by epoxidation with m-chloroperoxybenzoic acid. The isomeric syn-diol epoxides were synthesized by base-catalyzed (Amberlyte IRA-400) cyclization of the bromo triol derivatives which in turn were prepared from the respective dihydrodiols by treatment with N-bromoacetamide in aqueous THF. New methods were employed for the preparation of 4- and 10-hydroxyBjF which are precursors for BjF-4,5-dihydrodiol and BjF-9,10-dihydrodiol. Cyclodehydration of 2-[2-(9-methoxy-11-hydroxybenzo[a]fluoren-11-yl)ethyl]-1,3-dioxane in polyphosphoric acid afforded 4-methoxyBjF (from which the phenol is readily prepared) in 87% yield. Reaction of 1-(4-methoxyphenyl)-acenaphthylene with ethyl diazoacetate is catalyzed by copper-bronze and gave a mixture of diastereomeric cyclopropane carboxylates. These were converted to the corresponding aldehydes by diisobutylaluminum hydride reduction and Swern oxidation followed by cyclodehydration with polyphosphoric acid to give 10-methoxyBjF in 91% yield. It had previously been reported that reduction of BjF-4,5-quinone to BjF-4,5-dihydrodiol occurs in low yield due to overreduction to a mixture of tetrahydro diols and triols. We now report that complexation of the quinone with silver nitrate followed by reduction with potassium borohydride in the presence of oxygen affords BjF-4,5-dihydrodiol in 91% yield.
Aroyl chlorides react with acyclic and cyclic alkenes in the presence of a rhodium catalyst to give Mizoroki–Heck type and cyclization products, respectively. A rhodium-ethylene complex, [RhCl(C2H4)2}2], showed excellent performance for these reactions. Notably, the reactions can be conducted effectively under base- and phosphane-free conditions.
在铑催化剂的存在下,芳酰氯与无环和环状烯烃反应,分别得到Mizoroki-Heck型和环化产物。铑-乙烯络合物[RhCl(C 2 H 4)2 } 2 ]显示出对于这些反应的优异性能。值得注意的是,该反应可以在无碱和无膦的条件下有效地进行。