Several 3,4-disubstituted 2,5-dihydro-1H-pyrrol-1-yloxyl radicals were synthesized. 2,5-Dihydro-3-hydroxymethyl-2,2,5,5-tetramethyl-1H-pyrrol-1-yloxyl radical (1) was reacted with triethyl orthoacetate in a Claisen rearrangement to give the exoolefinic compound 2. This was converted to its 1-acetoxyl derivative 3, which was then brominated in the allylic position. Subsequent rearrangement gave the endoolefinic compound 1-acetoxyl-4-bromomethyl-3-ethoxycarbonylmethyl-2,2,5,5-tetramethyl-1H-pyrrole radical (4). The allylic bromine could be replaced with nucleophiles (NaSCN, KSeCN, thiourea, selenourea, NaN3 and KSSO2Me) to give 5a-e and 26. The diamagnetic thiocyanates and selenocyanates could be reduced with sodium borohydride to the free thiol and selenol monoradicals, which were oxidized to reversible, ester-functionalized disulfide or diselenide diradical reagents 24 and 25.
合成了几个3,4-二取代的2,5-二氢-1H-
吡咯-1-氧基自由基。2,5-二氢-3-羟甲基-2,2,5,5-四甲基-1H-
吡咯-1-氧基自由基(1)经Claisen重排反应与三乙基原
乙酸酯反应,得到外烯烃化合物2。将其转化为1-乙酸氧基衍
生物3,然后在烯丙位进行
溴化。随后的重排反应得到内烯烃化合物1-乙酸氧基-4-
溴甲基-3-乙氧羰甲基-2,2,5,5-四甲基-1H-
吡咯自由基(4)。烯丙位的
溴可以被亲核试剂(NaSCN、KSeCN、
硫脲、
硒脲、NaN3和KSSO2Me)取代,得到5a-e和26。无磁性的
硫氰酸盐和
硒氰酸盐可以用
硼氢化钠还原成自由的
硫醇和
硒醇单自由基,这些自由基被氧化成可逆的、酯功能化的二
硫化物或二
硒化物双自由基试剂24和25。