The regioselectivity of the reaction of mesitonitrile oxide with o-hydroxystilbene in favour of the 5-(2-hydroxyphenyl) isomer (regioisomeric ratio 5:1) is accounted by a directing hydrogen bonding model, while for reactions of the p-hydroxy- and p-methoxystilbene which show a 2:1 ratio between the 5- and 4-regioisomer, an electron-donor effect is invoked. These phenomena of regioselectivity are supported by semiempirical AM1 calculations.
The regioselectivity of the reaction of mesitonitrile oxide with o-hydroxystilbene in favour of the 5-(2-hydroxyphenyl) isomer (regioisomeric ratio 5:1) is accounted by a directing hydrogen bonding model, while for reactions of the p-hydroxy- and p-methoxystilbene which show a 2:1 ratio between the 5- and 4-regioisomer, an electron-donor effect is invoked. These phenomena of regioselectivity are supported by semiempirical AM1 calculations.
Cycloadditions of mesitonitrile oxide with hydroxy- and methoxy-substituted stilbenes. A directing hydrogen bonding model
CHIACCHIO, Ugo;PISTARA', Venerando;RESCIFINA, Antonio
1998-01-01
Abstract
The regioselectivity of the reaction of mesitonitrile oxide with o-hydroxystilbene in favour of the 5-(2-hydroxyphenyl) isomer (regioisomeric ratio 5:1) is accounted by a directing hydrogen bonding model, while for reactions of the p-hydroxy- and p-methoxystilbene which show a 2:1 ratio between the 5- and 4-regioisomer, an electron-donor effect is invoked. These phenomena of regioselectivity are supported by semiempirical AM1 calculations.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
