New Anellation Methods for the Synthesis of 8<i>H</i>-Heptaleno[1,10-<i>bc</i>]furans,-pyrroles, and -thiophenes
作者:Cornelia Hörndler、Hans-Jürgen Hansen
DOI:10.1002/hlca.19970800820
日期:1997.12.15
Heptaleno[1,2-c]furan-6-carbaldehydes such as 8 or their thiocarbaldehyde or iminomethyl derivatives easily undergo thermal cyclization, followed by a [1,5]-H shift, to give the corresponding heptalenodifurans, thienoheptalenofurans, as well as furoheptalenopyrroles (cf. Schemes 2 and 3). Generation of the 6-acetyl derivative of 8 from the corresponding secondary alcohol 15 with 1-hydroxy-1,2-benziodoxol-3(1H)-one
七聚[1,2 - c ]呋喃-6-甲醛(例如8)或其硫代甲醛或亚氨基甲基衍生物很容易进行热环化,然后发生[1,5] -H移位,从而得到相应的七烯二呋喃,噻吩庚烷呋喃以及呋喃庚二烯吡咯(参见方案2和3)。在0°下由相应的仲醇15与1-羟基-1,2-苯并恶唑醇-3(1 H)-一-一氧化物(IBX)生成8的6-乙酰基衍生物(参见方案4)直接导致形成环化产物16其在室温下静置时经历[1,5]-σH移至最终的呋喃17。1-甲酰基庚烯-4,5-二羧酸酯(例如9)也可以进行热环化,然后进行[1,5] -H转移,生成相应的8 H-庚基[1,10 - bc ]呋喃-5,6-二羧酸11。用Lawesson试剂进行三硫杂环丁烷化反应时,直接生成9相应的七聚噻吩13 (参见方案3)。