Diastereoselective Synthesis of 6 ''-(Z)- and 6 ''-(E)-Fluoro Analogues of Anti-hepatitis B Virus Agent Entecavir and Its Evaluation of the Activity and Toxicity Profile of the Diastereomers

作者：Kumamoto Hiroki^*; Fukano Misato; Nakano Tomohiko; Iwagami Keito; Takeyama Chiaki; Kohgo Satoru; Imoto Shuhei; Amano Masayuki; Kuwata Higashi Nobuyo; Aoki Manabu; Abe Hiroshi; Mitsuya Hiroaki; Fukuhara Kiyoshi; Haraguchi Kazuhiro

来源：Journal of Organic Chemistry, 2016, 81(7): 2827-2836.

DOI：10.1021/acs.joc.6b00105

A method for the diastereoselective synthesis of 6 ''-(Z)- and 6 ''-(E)-fluorinated analogues of the anti-HBV agent entecavir has been developed. Construction of the methylenecyclopentane skeleton of the target molecules has been accomplished by radical-mediated 5-exo-dig cyclization of the selenides 6 and 15 having the phenylsulfanylethynyl structure as a radical accepting moiety. In the radical reaction of the TBS-protected precursor 6, (Z)-anti-12 was formed as a major product. On the other hand, TIPS-protected 15 gave (E)-anti-12. The sulfur-extrusive stannylation of anti-12 furnished a mixture of geometric isomers of the respective vinylstannane, whereas benzoyl-protected 17 underwent the stannylation in the manner of retention of configuration. Following XeF2-mediated fluorination, introduction of the purine base and deoxygenation of the resulting carbocyclic guanosine gave the target (E)- and (Z)-3 after deprotection. Evaluation of the anti-HBV activity of 3 revealed that fluorine-substitution at the 6 ''-position of entecavir gave rise to a reduction in the cytotoxicity in HepG2 cells with retention of the antiviral activity.

• 出版日期2016-4-1