作者:Regina Sparrapan、Maria Anita Mendes、Marcos N. Eberlin
DOI:10.1002/(sici)1096-9888(200002)35:2<189::aid-jms929>3.0.co;2-i
日期:2000.2
of differently substituted cyclic ionic diketals is performed in MS(3) experiments via sequential mono- and double transacetalization of O=C=N(+)=C=O and O=C=CH(+)=C=O with different acetals. With cyclic acetals, the acylium-thioacylium ion O=C=N(+)=C=S reacts promptly and selectively by mono-transacetalization at its acylium site, but the free thiacylium site of its cyclic ionic ketal is nearly unreactive
报道了O = C = X(+)= C = O型(X = N,CH)的二酰基离子的新型气相反应:用环缩醛或缩酮进行双缩醛化。该反应是放热的且高效的,并且形成新的一类高电荷离域离子:环状离子二缩酮。五级双级和三级质谱(MS(2)和MS(3))实验表明,O = C = N(+)= C = O和O = C = CH(+)= C = O,而不同取代的环状离子二缩酮的合成是在MS(3)实验中通过依次将O = C = N(+)= C = O和O = C = CH(+)的单缩醛和双缩醛进行的用不同的乙缩醛= C = O。对于环状缩醛,酰基-硫代酰基离子O = C = N(+)= C = S在其酰基位点通过单反缩醛化反应迅速而选择性地发生反应,但是它的环状离子缩酮的游离硫胞嘧啶位点几乎不会通过双缩醛化反应。因此,仅O = C = N(+)= C = S的acy基位点可以通过反缩醛化有效地保护。低能量MS(3)碰撞诱导的O