6900-99-8Relevant articles and documents
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Vaquette,J. et al.
, p. 1257 - 1259 (1974)
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A Short Total Synthesis of Benzophenanthridine Alkaloids via a Rhodium(III)-Catalyzed C-H Ring-Opening Reaction
Aravindan, Narasingan,Jeganmohan, Masilamani
, p. 14826 - 14843 (2021/10/20)
The biologically important naturally available benzophenanthridines were prepared efficiently in three steps with overall good yields. A new synthetic methodology involving a rhodium(III) catalyzed redox-neutral ring-opening of 7-azabenzonorbornadienes with aromatic aldoximes is developed to synthesize the target molecules. The developed C-H ring-opening reaction is highly diastereoselective and compatible with various sensitive functional group substituted aromatic aldoximes as well as substituted 7-azabenzonorbornadienes. The ring-opening products were transformed into highly sensitive 13,14-dehydrobenzo phenanthridine derivatives by HCl hydrolysis. Subsequently, 13,14-dehydrobenzophenanthridines were converted into biologically important benzophenanthridine alkaloids in the presence of DDQ. A possible reaction mechanism was proposed for the C-H ring-opening reaction and supported by the deuterium labeling studies.
Method for synthesizing benzophenanthridine and protoberberine alkaloids through modular diversity regulation and control
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Paragraph 0517-0521, (2021/05/29)
The invention discloses a method for synthesizing benzophenanthridine and protoberberine alkaloids through modular diversity regulation and control. The method comprises the following steps: improving a substituent group of a high-iodine salt leaving group, generating pyridine alkyne under the action of relatively mild potassium tert-butoxide, and carrying out [4 + 2] cycloaddition reaction on the pyridine alkyne and diene to obtain polysubstituted isoquinoline ring precursor compounds. Ring opening and aromatization of the isoquinoline ring precursor are realized by developing a novel iridium-catalyzed cross-coupling method, polysubstituted isoquinoline ring compounds with connecting capacity are efficiently synthesized, and then the polysubstituted isoquinoline ring compounds are coupled with a high-activity polysubstituted cyclic boric acid to obtain 3-aryl isoquinoline high-grade intermediates. Through application of two different chemical principles, regulation and control of the 3-aryl isoquinoline high-grade intermediates are realized, and benzophenanthridine and protoberberine alkaloids are modularly, diversely and efficiently synthesized.
Expeditious approach to pyrrolophenanthridones, phenanthridines, and benzo[ c ]phenanthridines via organocatalytic direct biaryl-coupling promoted by potassium tert -butoxide
De, Subhadip,Mishra, Sourabh,Kakde, Badrinath N.,Dey, Dhananjay,Bisai, Alakesh
, p. 7823 - 7844 (2013/09/12)
A methodology involving a "transition metal-free" intramolecular biaryl-coupling of o-halo-N-arylbenzylamines has been developed in the presence of potassium tert-butoxide and an organic molecule as catalyst. The reaction appears to proceed through KOtBu-promoted intramolecular homolytic aromatic substitution (HAS). Interestingly, this biaryl coupling also works in the presence of potassium tert-butoxide as sole promoter. On extending our approach further, we found that N-acyl 2-bromo-N-arylbenzylamines undergo a one-pot N-deprotection/biaryl coupling followed by oxidation, thus offering an expeditious route to the phenanthridine and benzo[c]phenanthridine skeletons. The strategy has been applied to a concise synthesis of Amaryllidaceae alkaloids viz. oxoassoanine (1b), anhydrolycorinone (1d), 5,6-dihydrobicolorine (2d), trispheridine (2b), and benzo[c]phenanthridines alkaloids dihydronitidine (3b), dihydrochelerythidine (3d), dihydroavicine (3f), nornitidine (3h), and norchelerythrine (3j).
