Access to indoles via Diels‐Alder reactions of 3‐vinylpyrroles

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Abstract magnified image N ‐ p ‐Toluenesulfonyl‐3‐vinylpyrrole underwent endo ‐addition [4 + 2] cycloaddition reactions with maleimides and benzoquinones, followed by isomerization to give tetrahydroindoles in good yields. Dehydrogenation with activated MnO 2 in refluxing toluene gave the corresponding indoles in fair to good yields. Detosylation via saponification or with magnesium in refluxing methanol gave the N ‐H indoles in moderate to good yields. This method for formation of indoles is both convergent and versatile and uses starting materials that are conveniently prepared. J. Heterocyclic Chem., (2009).