This in {TAIL ~ turn} is then {HEAD ~ ring} closed by a stereospecific process of inversion with pyridine in p toluenesulfonyl chloride to obtain dibenzofuran 
This in { TAIL ~ turn } is then { HEAD ~ ring } closed by a stereospecific process of inversion with pyridine in p toluenesulfonyl chloride to obtain dibenzofuran
OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH