5-Hydroxyindoles by intramolecular alkynol-furan diels-alder cycloaddition.

Matthew LaPorte, Ki Bum Hong, Jie Xu, Peter Wipf

Index: J. Org. Chem. 78(1) , 167-74, (2013)

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Abstract

A convergent approach provides a convenient access to synthetically and biologically useful 3,4-disubstituted 5-hydroxyindoles. The one-pot procedure uses microwave heating to initiate an intramolecular [4 + 2]-cycloaddition of an alkynol segment onto a furan followed by a fragmentation, aromatization, and N-Boc deprotection cascade. Yields range from 15 to 74%, with aromatic substituents providing better conversions. 4-Trimethylsilylated analogues undergo a 1,3-silatropic rearrangement to give the O-TMS ethers.