Abstract A study of the reactivity of 2-substituted 1,3-butadienes with nitrosocarbonyl compounds in the 4+2 cycloaddition has been carried out showing that the regioselectivity involves a delicate balance of steric… Click to show full abstract
Abstract A study of the reactivity of 2-substituted 1,3-butadienes with nitrosocarbonyl compounds in the 4+2 cycloaddition has been carried out showing that the regioselectivity involves a delicate balance of steric and electronic effects. 2-Aryl 1,3-butadienes favor the distal isomer with the magnitude of preference ranging from 4:1 to 15:1 depending on the nature of the nitrosocarbonyl group. However, when bulky 2-substituted dienes are used the proximal isomer is formed preferentially. The results obtained, together with previous theoretical calculations and experimental data, provide further data to aid in synthetic planning.
               
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