The Directing Ability of the Methylthio Substituent in Lithiathion Reactions of Thiophenes
A method for regiospecific electrophilic substitution of 3-(methylthio)thiophene in either the 2- or 5-position has been developed on the basis of a combination of bromination, metal-halogen exchange, and controlled rearrangement of 2-bromo-5-lithio-3-(methylthio)thiophene to 5-bromo-2-lithio-3-(methylthio)thiophene.
HIGH-YIELD SYNTHESES OF 2,3-DISUBSTITUTED FURANS AND THIOPHENES
The course of lithiation of furan- and thiophene-2-carboxylic acids is critically dependent on the identity of the lithium base allowing high-yielding syntheses of 2,3- and 2,5-disubstituted thiophenenes: the proposed use of a trimethylsilyl blocking group to control metallation in the furan acid provides a useful route to 2,3-disubstituted furans.
Carpenter, Andrew J.,Chadwick, Derek J
p. 1777 - 1780
(2007/10/02)
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