Reactions of 2,3-Dibromo-2-methylpropanamides Promoted by Potassium tert-Butoxide

2,3-Dibromo-2-methylpropanamides with different substituents on the nitrogen atom were synthe­sized, and their transformations by the action of potassium tert -butoxide in THF were studied. 2,3-Dibromo- N -(4-methoxyphenyl)-2-methylpropanamide and 2,3 - dibromo- N -(2,5-dibromo-4-methoxyphenyl)-2-methyl­propan­amide reacted with 1–2 equiv of t -BuOK to give the corresponding N-substituted 3-bromo-3-methyl- and 3-methylideneazetidin-2-ones with acceptable yields and selectivity. Increase of the amount of t -BuOK to 3–5 equiv led to significant reduction of the yield of vinyl bromides and 3-methylideneazetidin-2-ones. On the other hand, the reaction of 2,3-dibromo- N -( tert -butyl)-2-methylpropanamide with t -BuOK afforded 3-( tert -bu­toxymethyl)-1- tert -butylazetidin-2-one with a good yield and selectivity.