 If the ylide carbon is substituted with an electron @-@ withdrawing group ( EWG ) , the reagent is referred to as a stabilized ylide . These , similarly to sulfoxonium reagents , react much slower and are typically easier to prepare . These are limited in their usefulness as the reaction can become prohibitively sluggish : examples involving amides are widespread , with many fewer involving esters and virtually no examples involving other EWG 's . For these , the related Darzens reaction is typically more appropriate . 
 If the ylide carbon is substituted with an electron @-@ withdrawing group ( EWG ) , the reagent is referred to as a stabilized ylide . These , similarly to sulfoxonium reagents , react much slower and <a href='drop_aux' title='1'><mark>are</mark></a>typically easier to prepare . These are limited in their usefulness as the reaction can become prohibitively sluggish : examples involving amides are widespread , with many fewer involving esters and virtually no examples involving other EWG <a href='null_genetive' title='2'><mark>'s</mark></a>. For these , the related Darzens reaction <a href='drop_aux' title='3'><mark>is</mark></a>typically more appropriate . 
If the ylide carbon is substituted wit an electron @-@ withdrawing group ( EWG ) , da reagent is referred to as a stabilized ylide . These , similarly to sulfoxonium reagents , react much slower and typically easier to prepare . These are limited in their usefulness as the reaction can become prohibitively sluggish : examples involving amides r widespread , with many fewer involving esters and virtually no examples involving other EWG  . fir dem , tdarelated Darzens reaction typically more appropriate .