2-chloro tiophene + buLi : ortho lithiation vs metal-halide exchange

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I dont know, I guess you gett lithiation in the 5-position. Can you use Scifinder or Reaxys? If you want to be sure you can use LDA to get pure 5-metalation. If you want metalation in the 2-position you can use magnesium and make a Grignard. Its possible you need to use excess magnesium+1,2-dichloroethane to get good Grignard.

Thanks.
No i can't

So is LDA  better than BuLi in tiophene orto lithiation?

You dont get halogen-metal exchange with LDA, you only pick the acidic 5-proton.

I dont know, I guess you gett lithiation in the 5-position. Can you use Scifinder or Reaxys? If you want to be sure you can use LDA to get pure 5-metalation. If you want metalation in the 2-position you can use magnesium and make a Grignard. Its possible you need to use excess magnesium+1,2-dichloroethane to get good Grignard.

Quote from:

You dont get halogen-metal exchange with LDA, you only pick the acidic 5-proton.

Thanks!!