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Why is there a retention of configuration in Hofmann bromamide degradation/Hofmann rearrangement?

I would think that there should be an inversion of configuration due to the migration of alkyl group to the other side. Why is this not so?

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  • $\begingroup$ The only group which can have a stereocenter in a substrate for the Hofmann rearrangement is the "R-" group to which the primary amide (-CONH2) is attached. In all the steps of the reaction, the R group is never involved (no electron transfer is made from or to the R group), so the configuration is not touched. Which step is not clear to you? $\endgroup$ – The_Vinz May 20 '19 at 4:43
  • $\begingroup$ I mean the absolute configuration not the stereocentre. Basically, why the Fisher projection remains same. $\endgroup$ – user600016 May 20 '19 at 4:48
  • $\begingroup$ I have added two examples from the book Solmon and Fryle. $\endgroup$ – user600016 May 20 '19 at 4:53
  • $\begingroup$ Tip: Following the mechanism for the rearrangement given by your book, write with the curved-arrow formalism a mechanism of the rearrangement for those two molecules. $\endgroup$ – The_Vinz May 20 '19 at 5:00

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