R1 and {HEAD ~ R2} are independently H, C1 C18 alkyl; or R1 in combination with R2 forms a saturated 5 or 6 membered heterocycle that is a piperidine, {TAIL ~ a morpholine}, a pyrrolidine or a piperazine 
R1 and { HEAD ~ R2 } are independently H , C1 C18 alkyl ; or R1 in combination with R2 forms a saturated 5 or 6 membered heterocycle that is a piperidine , { TAIL ~ a morpholine } , a pyrrolidine or a piperazine
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 TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH