α-Lithio-3-indolylacetate Synthons: Generation and Synthetic Utilization

Article abstract of DOI:10.1021/jo01291a014

3-Indolyl-, (N-methyl-3-indolyl)-, and (N-methyl-2-methyl-3-indolyl)acetic acids are quantitatively α-lithiated directly with n-BuLi, while methyl (N-methyl-3-indolyl)acetate is quantitatively α-lithiated with lithium diisopropylamide (LDA) at -78 deg C in THF.These useful synthons react readily with electrophiles such as alkyl halides, chlorosilanes, and ketones to afford the respective α-alkyl derivatives 1, ketene silyl acetals 2, and β-hydroxy acids 3.Photosensitized oxygenation of the ketene silyl acetals 2 affords 1,2-diox-4-ene products through (2 + 4) cycloaddition with singlet oxygen.