The acyl substituent in the 10 position may also be substituted with electron donating groups so long as {HEAD ~ the acyl substituent} is {TAIL ~ electron} withdrawing overall 
is
The acyl substituent in the 10 position may also be substituted with electron donating groups so long as { HEAD ~ the acyl substituent } is { TAIL ~ electron } withdrawing overall
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL OTH OTH