Syntheses and evaluation of halogenated cytisine derivatives and of bioisosteric thiocytisine as potent and selective nAChR ligands
作者:P Imming
DOI:10.1016/s0223-5234(01)01222-3
日期:2001.4
We have developed one-step syntheses of halogenated derivatives of (-)-cytisine featuring a halogen substituent at positions 3, 5 or 3 and 5 of the 2-pyridone fragment, and prepared the novel bioisosteric thiocytisine by oxygen-sulphur exchange. The affinities of these pyridone-modified analogs of (-)-cytisine for (alpha (4))(2)(beta (2)),(3) and alpha7* nAChRs in rat forebrain membranes were determined by competition with (+/-)-[H-3]epibatidine and [H-3]MLA, respectively. The 3-halocytisines 7 possess subnanomolar affinities for (alpha4)(2)(beta2)(3) nAChRs, higher than those found for (-)-cytisine as well as for the 5-halocytisines 8 and 3,5-dihalocytisines 6. In contrast to the parent alkaloid the 3-halogenated species display much a higher affinity for the alpha7* nAChR subtype. The most potent molecule was 3-bromocytisine (7b) with preferential selectivity (200-fold) for the (alpha4)(2)(beta2)(3) subtype [K-i = 10 pM (alpha4 beta2) and 2.0 nM (alpha7*)]. Replacement of the lactam with a thiolactam pharmacophore to thiocytisine (12) resulted in a subnanomolar affinity for the (alpha4)(2)(beta2)(3) nAChR subtype (K-i = 0.832 nM), but in a drastic decrease of affinity for the alpha7* subtype; thiocytisine (12) has a K-i value of 4000 nM (alpha7*), giving a selectivity of 4800-fold for the neuronal (alpha4)(2)(beta2)(3)-nAChR and thus displaying the best affinity-selectivity profile in the series under consideration. (C) 2001 Editions scientifiques et medicales Elsevier SAS.
Thionation of quinolizidine alkaloids and their derivatives via Lawesson’s reagent
作者:Alena V. Koval’skaya、Polina R. Petrova、Dmitry O. Tsypyshev、Alexander N. Lobov、Inna P. Tsypysheva
DOI:10.1080/14786419.2020.1868460
日期:2022.7.18
Abstract Direct thionation of quinolizidinealkaloids (-)-cytisine, methylcytisine, thermopsine and some of their carbonyl derivatives was realized. It was established that carrying out of the reaction in the boiling toluene with 0.5 eq. of Lawesson’s reagent (LR) is most effective for synthesis of thio analogues of methyl-, allyl-, benzylcytisine and thermopsine. It was found, that formation of thioamides