Question

Hi, how do we choose if we should do 1,2 or 1,4 addition? What tells that 1,4 is major product instead of 1,2?

Luuuu No Date sth Sept 19 N° 33 Cring closing Reaction) Cyclization vuit HEWITT Hi NE PRETRP TP TP TR TRE ARE 1,2- addition OH + - R-NH₂ N - O 1,4- addition michael addition) R-NH2 major product +

Answer 1

If the nucleophiles are strong such as grignard, nBLi.. Then 1,2 addition takes place. At low temperatures kinetically stable 1,2 addition product is favourable

If the nucleophiles are weak and soft such as gilman, SH(-), NH2(-) then 1,4 addition favourable.thermo dynamically stable.. 1,4 addition also favours at high temperatures