Polar vs steric effects in the 1,3-dipolar cycloaddition reactions of acetonitrile oxide and 2-endO-acetoxy-5-halo-7-oxabicyclo[2.2.1]hept-5-en-2-exo-carbonitrile
作者:Odön Arjona、Alfonso de Dios、Roberto Fernandez de la Pradilla、Araceli Mallo、Joaquin Plumet
DOI:10.1016/s0040-4020(01)81474-5
日期:——
The regioselectivity of the cycloaddition reactions between acetonitrile oxide and a number of 7-oxabicyclo[ 2.2.1]hept-5-enes is discussed. Acetonitrile oxide adds with complete regioselectivity to 2-endo-acetoxy-5-halo-7-oxabicyclo[2.2.1]hept-5-en-2-exo-carbonitriles. Kinetic measurements indicate a more polar transition state for 2a than for the unsubstituted substrate la