Retrosynthetic analysis chemoselectivity problems

Both (a) and (b) pose problems of chemoselectivity as it would be hard to alkylate the phenol in the presence of the basic nitrogen atom. Between (c) and (d), (c) appears to be the better choice because the next disconnection after (d) will have to be an alkylation of O in the presence of an NH2 group. To avoid chemoselectivity problems like this, we want to try and introduce reactive groups late in the synthesis. In terms of retrosynthetic analysis, then, we can formulate another guideline. 

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See also in sourсe #XX -- [ ]

See also in sourсe #XX -- [ ]

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