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四氢原小檗碱是一类天然存在的生物碱,新近研究表明其左旋异构体是脑内多巴胺受体 的拮抗剂,而右旋体则极可能是多巴胺的排空或释放剂。为了研究它们的氚标记化合物的生物活性,我们用NaBH_4还原法制备了氚代位置在C_8和C_(14)位上的三种四氢原小檗碱,即氘代四氢小檗碱(THB-d_2),氘代四氢巴马汀(THP-d_2)和氘代千金藤立定(SPD-d_2)。氘代物的质谱显示它们的分子离子峰均比非氚代物增加2,RDA产生的两碎片峰均比非氘代物增加质量1。故可推定反应中分子上了两个氘原子,氘代位置只能分别在C_8和C_(18)位上。从氘代物的′H-NMR看,C_(14)位质子信号消失,表明该位置为氘取代。C_8位质子信号由非氘代物的两组二重峰(AB型)变成氘代物的两个单峰,每单峰积分为0.5H,两单峰具有较大的化学位移值之差(Δδ=0.7),表明B/C环应为反式稠合。IR在2800cm~(-1)处Bohlmann带亦可作证。对于C_8位置质子信号可解释为由于氘负离子首先还原平面型季铵阳离子成二氢化物时没有优势进攻面,氘在横或竖键上的分布几率均等,故C_8-H两单峰积分各为0.5H。
Tetrahydroprotoberberines are a naturally occurring class of alkaloids. Recent studies have shown that levorotatory is an antagonist of dopamine receptors in the brain, whereas dextral is most likely an emptying or releasing dopamine. In order to study the biological activity of their tritium-labeled compounds, we prepared three tetrahydroberberines with tritiated positions C_8 and C_ (14) using the NaBH_4 reduction method, namely, deuterated tetrahydroberberine (THB -d_2), deuterated tetrahydropalmatine (THP-d_2) and deuterium sesquiterpenidine (SPD-d_2). Mass spectrometry of deuterated compounds showed that both of their molecular ion peaks were increased by 2 compared with that of non-tritiated products, and both fragments produced by RDA increased mass 1 more than non-deuterated ones. Therefore, it can be presumed that the molecule has two deuterium atoms in the reaction, and the deuteration position can only be at C_8 and C_ (18) respectively. From the deuteron ’H-NMR, the C_ (14) proton signal disappeared, indicating that the position of deuterium substitution. The C_8-site proton signal was changed from two non-deuterated doublets (AB type) to two singlets of deuteride with an integral per peak of 0.5H, with a difference between the two chemical shifts (Δδ = 0.7), indicating that the B / C ring should be trans-fused. The Bohlmann band with IR at 2800cm -1 can also be testified. For the C_8 position proton signal can be interpreted as the deuterium anion first planar planar quaternary ammonium cation into dihydride has no advantage offensive surface, deuterium in the horizontal or vertical key distribution probability equal, so C_8-H two single peak integral each 0.5H.