73609-07-1Relevant academic research and scientific papers
Chemical Transformation of Protoberberines. V. Photochemical Valence Isomerization of Berberinephenolbetaines to 8,14-Cycloberbines, Versatile Aziridine Derivatives for a Novel and Efficient Entry to Spirobenzylisoquinolines and Benzindenoazepines
Hanaoka, Miyoji,Mukai, Chisato,Nagami, Kazuyoshi,Okajima, Keiko,Yasuda, Shingo
, p. 2230 - 2240 (2007/10/02)
Irradiation of berberinephenolbetaine (12a) and its 8-alkyl derivatives (12b-e) readily effected valence isomerization to afford the corresponding novel 8,14-cycloberbines (13a-e) in high yields.On treatment with ethyl chloroformate, the 8,14-cycloberbines (13a, 13b, and 13c) were efficiently converted to the spirobenzylisoquinoines (14, 15, and 16-18, respectively) via regioselective C8-N bond cleavage.The 8,14-cycloberbine (13a), on treatment with methyl iodide, provided the benzindenoazepine (21) through regioselective C14-N bond cleavage, whereas 8-methyl- and 8-ethyl-8,14-cycloberbine (13b and 13c) gave 8-methylidene- and (Z)-8-ethylidene-spirobenzylisoquinoline (22 and 23), respectively.Irradiation of 8-methoxyberberinephenolbetaine (26) directly afforded the spirobenzylisoquinoline (31) having a ketone and a ketal on the five-membered ring.The product (31) was converted easily to a variety of spirobenzylisoquinolines such as the diketone (36), the hydroxy-ketal (38), and the keto-alcohol derivatives (41 and 42) in excellent yieds.Keywords - photochemical valence isomerization; berberinephenolbetaine; 8,14-cycloberbine; regioselective ring cleavage; spirobenzylisoquinoline; benzindenoazepine; ethyl chloroformate; methyl iodide.
