Synthesis of 5,5-dimethyl-1-pyrroline-N-oxide-2-14C

Simplified Synthesis of Isotopically Labeled 5,5-Dimethyl-pyrroline N-Oxide

“…15–20% (as also reported by Le et al . [7]). In retrospect, for future syntheses it may be beneficial to protect the aldehyde as dioxolane before the reduction step [5] because Rosen et al .…”

“…The corresponding pentanal was formed by reduction with diisobutylaluminum hydride, as described by Le et al [ 7 ]. Some experimental details of the protocol were modified according to [ 13 ].…”

“…Later, Le et al . [7] published a synthesis of 2- 14 C-DMPO that avoided the direct Michael reaction of nitropropane with methyl acrylate, thereby improving the low yield and eliminating the difficult purification of this step. For the synthesis of isotopically labeled DMPO, Pou et al .…”

“…The classical synthesis of DMPO, as reported by Janzen et al [ 5 ], is based on the synthesis of pyrrolines [ 6 ]. Later, Le et al [ 7 ] published a synthesis of 2- 14 C-DMPO that avoided the direct Michael reaction of nitropropane with methyl acrylate, thereby improving the low yield and eliminating the difficult purification of this step. For the synthesis of isotopically labeled DMPO, Pou et al [ 8 ] published an effective method starting from 15 N-hydroxylamine, which involved the use of hydrogen gas in an autoclave as well as a reaction with ozone derived from an ozone generator.…”

“…This principle has been used for nitrone spin trap synthesis [ 10 ]. Nitropropane was then used for a DMPO synthesis similar to that of Le et al [ 7 ] ( Scheme 1 ).…”