Synthesis of cis-(8b,14a)-hexahydro-14H-dibenzo[f,h]oxazolo[3,2-b]isoquinolin- 14-ones via photo cascade reaction

A concise method for the synthesis of cis-(8b,14a)-hexahydro-14H-dibenzo[f,h]oxazolo[3,2-b]isoquinolin-14-ones 2 via photo-induced 3-([1,1'-biphenyl]-2-yl)-1-(2-hydroxyethyl)pyridin-2(1H)-ones 1 was developed. Irradiation of 1 in the solution of toluene with a 313 nm UV light in the presence of HCl gave cis-(8b,14a)-9a-alpha-hexahydro-14H-dibenzo[f,h]oxazolo[3,2-b]isoquinoli n-14-ones and cis-(8b,14a)-9a-beta-hexahydro-14H-dibenzo[f,h]oxazolo[3,2-b]isoquinolin-14-ones 2 (2-alpha and 2-beta) in good yields. The protocol simultaneously constructs dearomatized phenanthrene ring and oxindolizidinones ring by photo cascade reaction to achieve high bonding efficiency and high atomic efficiency. Additionally, the antitumor activities of 2 was evaluated and compounds 2b-alpha, 2b-beta, 2j-beta and 2 k-alpha showed similar or better activity compared to the cisplatin against tumor cell lines of Leukemia HL-60, lung cancer A594, liver cancer SMMC-7721 and breast cancer MDA-MB-231. Graphical abstract Cis-(8b,14a)-9a-alpha-hexahydro-14H-dibenzo[f,h]oxazolo[3,2-b]isoquinolin-14-ones and cis-(8b,14a)-9a-beta-hexahydro-14H-dibenzo[f,h]oxazolo[3,2-b]isoquinolin-14-ones 2 (2-alpha and 2-beta) were obtained with a 313 nm UV light via photo-induced cyclization of 3-biphenyl-1-hydroxethylpyridin-2(1H)-ones 1 in high bonding efficiency, high atomic efficiency and chemical stereo-selectively.