The reaction is conveniently carried out in an inert organic solvent in the presence of a catalytic amount of {HEAD ~ an organic or inorganic acid} such as {TAIL ~ p toluenesulphonic acid} or dry hydrochloric acid 
such as
The reaction is conveniently carried out in an inert organic solvent in the presence of a catalytic amount of { HEAD ~ an organic or inorganic acid } such as { TAIL ~ p toluenesulphonic acid } or dry hydrochloric acid
OTH 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 HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH