alternatively, when {TAIL ~ two Rc groups} are attached to the same carbon atom, they form a 5–6 membered carbocyclic or heterocyclic spiro ring C consisting of carbon atoms, 0–4 ring heteroatoms selected from O, N, and {HEAD ~ Sp}, and 0–2 double bonds, provided that ring C contains other than a S—S, O—O, or S—O bond 
alternatively , when { TAIL ~ two Rc groups } are attached to the same carbon atom , they form a 5–6 membered carbocyclic or heterocyclic spiro ring C consisting of carbon atoms , 0–4 ring heteroatoms selected from O , N , and { HEAD ~ Sp } , and 0–2 double bonds , provided that ring C contains other than a S — S , O — O , or S — O bond
OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH