=Other structures=
===[http://v3.espacenet.com/publicationDetails/claims?CC=WO&NR=2007070607A2&KC=A2&FT=D&date=20070621&DB=EPODOC&locale=en_EP WO2007070607]===
[[Image:L1L11.jpg|thumb|center|500px]]
*R1-H,
*R2 is –C2H5 which matches with R1(alkyl) at 1st position of the generic structure