Highly Selective 5-Substitution of 3-Methylthiophene via Directed Lithiation
作者:Keith Smith、Mark Lewis Barratt
DOI:10.1021/jo062024f
日期:2007.2.1
Lithiation of 3-methylthiophene with lithium 2,2,6,6-tetra-methylpiperidide (LiTMP) is highly selective at the 5-position, and reaction with a range of electrophiles gives high yields of the corresponding 2,4-disubstituted thiophenes, even when unhindered electrophiles are used.
Synthesis of β-pyrrole and β-thiophene substituted 21,23-dithia and 21-monothiaporphyrins
作者:Neeraj Agarwal、Mangalampalli Ravikanth
DOI:10.1016/j.tet.2004.03.047
日期:2004.5
A series of beta-pyrrole and beta-thiophene substituted porphyrins with N2S2 and N3S porphyrin cores were synthesized and characterized. The introduction of substituents at beta-pyrrole and beta-thiophene carbons resulted in significant shifts in H-1 NMR, absorption and fluorescence maxima. These effects were attributed to alteration of the porphyrin ring current caused by substituents at beta-positions. (C) 2004 Elsevier Ltd. All rights reserved.
Practical Access to Metallo Thiophenes: Regioselective Synthesis of 2,4-Disubstituted Thiophenes
作者:Sylvie M. Asselin、Matthew M. Bio、Neil F. Langille、Ka Yi Ngai
DOI:10.1021/op100226k
日期:2010.11.19
accomplished by addition of 2-magnesio-4-methylthiophene to phthalic anhydride, providing the product with >40:1 regioselectivity. This also solved a chemoselectivity issue encountered with analogous lithio-thiophene reagents and cyclicanhydrides, or with magnesio-thiophene generated by simultaneous lithium-to-magnesium transmetalation/anhydride acylation. These alternative in situ transmetalation sequences