Tritiation of SR141716 by metallation-iodination-reduction: tritium-proton nOe study
Tritiation of SR141716 by metallation-iodination-reduction: tritium-proton nOe study
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DOI：
10.1002/jlcr.529.abs
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发表时间：
2002-01-01
影响因子：
1.8
通讯作者：
Burch, DF
中科院分区：
文献类型：
--
作者：
Seltzman, HH;Carroll, FI;Burch, DF
中枢大麻素受体拮抗剂 SR141716，N-(哌啶-1-基)-5-(4-氯苯基)-1-(2,4-二氯苯基)-4-甲基-1H-吡唑-3-甲酰胺，由市售起始原料合成。芳基肼与二酮缩合，随后碱促进中间体反亚胺的异构化/环化，得到吡唑酸，该吡唑酸通过其酰基氯转化为标题酰肼。通过金属化轻松碘化，然后用碘源进行原位捕获，得到了适度产率的碘化 SR141716。用氚气和催化剂选择性还原碘，同时保留结构中的三个芳基氯原子。氚化的 SR141716 表现出氚-质子 nOe，既明确地确定了氚的位置，又确定了所寻找的二芳基吡唑异构体。这项工作提供了一种制备优选碘化芳基底物的直接方法，该底物在催化还原中寻求选择性和高掺入性方面具有优势。版权所有 (C) 2002 John Wiley Sons, Ltd.
The central cannabinoid receptor antagonist SR141716, N-(piperidin-1-yl)-5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4-methyl-1H-pyrazole-3-carboxamide, was synthesized from commercially available starting materials. Condensation of an aryl hydrazine with a diketone followed by base promoted isomerization/cyclization of the intermediate anti-imine gave the pyrazole acid which was converted to the title hydrazide via its acid chloride. Facile iodination via metallation followed by in situ trapping with an iodine source gave a modest yield of the iodinated SR141716. The iodine was selectively reduced with tritium gas and catalyst while retaining the three aryl chlorine atoms in the structure. The tritiated SR141716 exhibited a tritium-proton nOe both definitively identifying the position of the tritium as well as the sought isomer of the diarylpyrazole. This work provides a direct method for the preparation of preferred iodinated aryl substrates that offer advantages where selectivity and high incorporation in catalytic reduction is sought. Copyright (C) 2002 John Wiley Sons, Ltd.