A synthesis of N-tosyl indole 15 starting from the pyrrole-2-carboxaldehyde 11 and acetal containing alkyl bromide 12 is shown overleaf. Identify intermediate 13 formed on treating the alkyl bromide 12 with magnesium. Explain how 13 then reacts with pyrrole 11 and identify compound 14 formed after aqueous work-up. Show how 14 is finally converted into indole 15 on treatment with acid (hint: the acetal group in 12 is a protected form of an aldehyde). Give mechanisms for each step of the transformation. Br H₂SO4 (aq) heat Ts 11 Ts= Mg 13 12 14 1 Ts 15

A synthesis of N-tosyl indole 15 starting from the pyrrole-2-carboxaldehyde 11 and acetal containing alkyl bromide 12 is shown overleaf. Identify intermediate 13 formed on treating the alkyl bromide 12 with magnesium. Explain how 13 then reacts with pyrrole 11 and identify compound 14 formed after aqueous work-up. Show how 14 is finally converted into indole 15 on treatment with acid (hint: the acetal group in 12 is a protected form of an aldehyde). Give mechanisms for each step of the transformation. Br H₂SO4 (aq) heat Ts 11 Ts= Mg 13 12 14 1 Ts 15

Organic Chemistry

8th Edition

ISBN:9781305580350

Author:William H. Brown, Brent L. Iverson, Eric Anslyn, Christopher S. Foote

Publisher:William H. Brown, Brent L. Iverson, Eric Anslyn, Christopher S. Foote

Chapter19: Enolate Anions And Enamines

Section19.9: Crossed Enolate Reactions Using Lda

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