linoleic acid 18 2 was synthesized by treating linoleic acid with an eqv of a buli tbuk sigma aidrich mix in hexane followed by quenching with d 2 o to improve yields this procedure needs to be repeated 3 4 times it was found that this procedure also generates a detectable amount of alpha deuterated product fab ms xe ions thioglycerine found 283 34 72 mi i 284 33 11 alpha monodeuteroderivative mi 1 285 34 10 alpha dideuteroderivative mi 1 the nature of u2018 284 u2019 and u2018 285 u2019 peaks was established using ms ms the substitution at alpha position can be prevented by utilizing transient ortho ester protection corey amp raju tetrahedron lett 1983 24 5571 but this step makes the preparation more expensive deoxyguanosine 268 mg 1 mmol aldrich was dissolved in 4 ml of d 2 o 10 pd c 27 mg 10 wt of the substrate aldrich was added and the mixture was stirred at 160 u00b0 c in a sealed tube under b 2 atmosphere for 24 h after cooling to rt the reaction mixture was filtered using a membrane filter millipore millex u00ae lg the filtered catalyst was washed with boiling water 150 ml and the combined aqueous fractions were evaporated in vacuo to give deoxyguanoside j as a white solid 246 mg 92 the structure of the nucleoside was confirmed by maldi tof voyager elite perseptive biosystems with hpa as a matrix found 268 112 mi 7 pd c catalyst prepared from pdcl 2 as described in chiriac et al 1999 42 377 385 was added to a solution of 8 bromodeoxyguanosine sigma and naoh in water the mixture was stirred in d 2 2 atm at 30 u00b0 c the catalyst was filtered off and the reaction mixture was.