 Catalytic reagents have been less successful , with most variations suffering from poor yield , poor enantioselectivity , or both . There are also issues with substrate scope , most having limitations with methylene transfer and aliphatic aldehydes . The trouble stems from the need for a nucleophilic sulfide that efficiently generates the ylide which can also act as a good leaving group to form the epoxide . Since the factors underlying these desiderata are at odds , tuning of the catalyst properties has proven difficult . Shown below are several of the most successful catalysts along with the yields and enantiomeric excess for their use in synthesis of ( E ) -stilbene oxide . 
 Catalytic reagents have been less successful , with most variations suffering from poor yield , poor enantioselectivity , or both . <a href='dey_it' title='1'><mark>There</mark></a> are also issues with substrate scope , most having limitations with methylene transfer and aliphatic aldehydes . The trouble <a href='uninflect' title='2'><mark>stems</mark></a> from the need for a nucleophilic sulfide <a href='null_relcl' title='3'><mark>that</mark></a>efficiently <a href='uninflect' title='4'><mark>generates</mark></a> the ylide which can also act as a good leaving group to form the epoxide . Since the factors underlying these desiderata are at odds , tuning of the catalyst properties <a href='been_done' title='5'><mark>has</mark></a> proven difficult . Shown below <a href='drop_aux' title='6'><mark>are</mark></a>several of the most successful catalysts along with the yields and enantiomeric excess for their use in synthesis of ( E ) -stilbene oxide . 
Catalytic reagents have been less successful , with most variations suffering from poor yield , poor enantioselectivity , or both . It is also issues witt substrate scope , most havin limitations with methylene transfer and aliphatic aldehydes . The trouble stem from da need for a nucleophilic sulfide efficiently generate the ylide which can also act as a gud leaving group to form the epoxide . Since the factors underlying these desiderata r at odds , tuning of tdacatalyst properties done proven difficult . Shown below several of the most successful catalysts along wid thdaields and enantiomeric excess fa their use in synthesis of ( E ) -stilbene oxide .