Medicinal and Process Chemistry Division and ‡Sophisticated Analytical Instrumental Facility, CSIR-Central Drug Research Institute , Lucknow 226001, India.
J Org Chem. 2013 Oct 18;78(20):10476-84. doi: 10.1021/jo401929q. Epub 2013 Oct 10.
We describe two simple straightforward syntheses of triazolo isoquinolines (3) and isochromenes (7) from 2-alkynylbenzaldehydes (1) as a common synthon. The synthetic strategy for 3 involves formation of the (E)-1-(2-nitrovinyl)-2-(alkynyl)benzene species 2 via condensation of synthon 1 with nitromethane followed by a [3 + 2] cycloaddition/extrusion of the nitro group/regioselective 6-endo cyclization domino sequence. In yet another strategy, the synthon 1 was condensed with nitromethane followed by electrophilic iodo cyclization of the resulting 2-nitro-1-(2-(alkynyl)phenyl)ethanol (6) to furnish iodo isochromene derivatives. The salient feature of the above two strategies involves formation of the corresponding heterocycles under metal-free conditions in good yields.
我们描述了两种从 2-炔基苯甲醛（1）作为共同合成子合成三唑异喹啉（3）和异色满（7）的简单直接的合成方法。3 的合成策略包括通过缩合合成子 1 与硝基甲烷形成（E）-1-（2-硝基亚乙烯基）-2-（炔基）苯物种 2，然后进行[3 + 2]环加成/硝基团的消除/区域选择性 6-endo 环化级联反应。在另一种策略中，合成子 1 与硝基甲烷缩合，然后对得到的 2-硝基-1-（2-（炔基）苯基）乙醇（6）进行亲电碘环化，得到碘代异色满衍生物。上述两种策略的突出特点是在无金属条件下以良好的收率形成相应的杂环。
