18090-57-8Relevant academic research and scientific papers
A General, Concise Strategy that Enables Collective Total Syntheses of over 50 Protoberberine and Five Aporhoeadane Alkaloids within Four to Eight Steps
Zhou, Shiqiang,Tong, Rongbiao
, p. 7084 - 7089 (2016/05/19)
A concise, catalytic, and general strategy that allowed efficient total syntheses of 22 natural 13-methylprotoberberines within four steps for each molecule is reported. This synthesis represents the most efficient and shortest route to date, featuring three catalytic processes: CuI-catalyzed redox-A3 reaction, Pd-catalyzed reductive carbocyclization, and PtO2-catalyzed hydrogenation. Importantly, this new strategy to the tetracyclic framework has also been applied to the collective concise syntheses of >30 natural protoberberines (without 13-methyl group) and five aporhoeadane alkaloids.
Reaction of Protoberberine-type Alkaloids. Part 12. A Facile Method for Regiospecific Oxygenation and Excited Oxidative Ring-cleavage of Berberine Alkaloids
Kondo, Yoshikazu,Imai, Jiro,Inoue, Hideo
, p. 911 - 918 (2007/10/02)
Regiospecific photo-oxygenation and photo-oxidative ring-cleavage of protoberberine alkaloids is described.Irradiation of a solution of dihydroberberine (1) in the presence of Rose Bengal under aerated conditions gave 13-oxidoberberine (3) along with berberine (2) in 80 and 7percent yields, respectively.In contrast, 7,8-dihydrocoralyne (5) gave 13-oxidocoralyne (7) in nearly quantitative yield when an aerated solution of (5) was heated in the dark.Irradiation of a solution of (3) containing Rose Bengal with visible light afforded 8,13a-epidioxy-9,10-dimethoxy-2,3-(methylenedioxy)- 13-oxo-5,6,13,13a-tetrahydro-8H-dibenzoquinolizine (11) in 90percent yield.Under the same conditions, however, (7) gave 2'-acetylpapaveraldine (14) in 88percent yield.On the other hand, when an alcoholic solution of (5) or (7) containing sodium alkoxide was irradiated with a mercury lamp (Vycol filter) under bubbling oxygen, 6,7-dimethoxyisoquinolone (16) and 3-alkoxy-5,6-dimethoxy-3-methylisobenzofuran-1(3H)-one (17) or (18) were obtained in moderate yields.A reaction mechanism which involves the initial formation of an epidioxy-intermediate was evidenced by the fact that the photolysis of (7) was carried out in the presence of borohydride anion to give (16) and 5,6-dimethoxy-3-methylisobenzofuran-1(3H)-one (19).Irradiation of (11) in the same fashion gave berberal (20) and 2-(2-formyl-3,4-dimethoxybenzoyl)-3,4-dihydro-6,7-(methylenedioxy)isoquinolin-1(2H)-one (21) in 72percent and 4percent yields, respectively.Possible mechanisms are also presented.Reduction of (3) with sodium borohydride gave (+/-)-ophiocarpine (9) and (+/-)-13-epiophiocarpine (10), with the ratio (9):(10) varying depending upon the nature of the alcohol used as solvent.An interpretation which rationalizes these observations is suggested.
