A substituent directed regioselective synthesis of aryl/pyronyl pendant unusual adipate and tetrahydronaphthalene

作者：Pratap Ramendra^*; Ram Vishnu Ji

来源：Tetrahedron Letters, 2008, 49(18): 3011-3014.

DOI：10.1016/j.tetlet.2008.02.148

• 2-carbethoxycyclopentanone
• 2-oxopyran
• ring transformation
• mercaptide ion

An efficient regioselective synthesis of pyronyl pendant ethyl methylthiocarbonylalkanoates 5 has been delineated from the base catalyzed reaction of suitably functionalized 2-pyranone 1 and 2-carbethoxycycloalkanones 2, 6 through successive substitution and regioselective ring opening by in situ generated mercaptide ion. To assess the effect of C-4 substituent on regioselectivity, reactions of 6-aryl-3-cyano-4-(piperidin-1-yl)-2-oxopyran 8 with 2-carbethoxycyclohexanone 6a and 2-carbethoxy-2-methyleyclohexanone 6b were carried out separately under analogous reaction conditions but the compounds isolated were identical and characterized as 4-aryl-8-methyl-2-piperidin-1-yl-5,6,7,8-tetrahydronaphthalene-1-carbonitriles 9. Ethyl 2-(5-amino-4'-bromo-4,6-dicyanobiphenyl-3-yl)-5-methylsulfanylcarbonylpentanoate 10 has also been prepared through base catalyzed ring transformation of ethyl 2-[6-(4-bromophellyl)-3-cyano-2-oxo-2H-pyran-4-yl]- 5-methylsulfanylcarbonylpentanoate 5d by malononitrile in DMF.

• 出版日期2008-4-28