Conjugate additions amines, sodium hydride

The addition of a nucleophilic carbon species to an zr,/3-unsaturated ketone, aldehyde, ester or nitrile is called Michael reaction. Other nucleophiles such as amines, alkoxides or thiolates react similarly. In this case sodium hydride generates the anion of tert-butanethiol which undergoes an 1,4-addition at the conjugated ester. Regeneration of the double bond by elimination of bromine leads to the thermodynamically more stable E-ester 20. 

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