Direct Introduction of Nucleophilic Carbanions to the g-Position of Na-Boc-protected Nb-Tryptophylpyridinium Salts without Electron Withdrawing Substituents at the b-Position
Acid-catalysed epimerization of indolo[2,3-a]quinolizidines. 1-, 2- and 3-monosubstituted alkyl derivatives
作者:Mauri Lounasmaa、Lars Miikki、Arto Tolvanen
DOI:10.1016/s0040-4020(97)00197-x
日期:1997.4
Acid-catalysed epimerization of 1-, 2- and 3-monosubstituted 1,2,3,4,6,7,12,12b-octahydroindolo[2,3-a]quinolizine alkyl derivatives in refluxing trifluoroacetic acid (TFA) leads to an equilibrium mixture of C-12b diastereomers. The thermodynamically more stable epimer predominates over the kinetically favoured epimer in a ratio of about 85:15 unless the substituent is at C-1, in which case the ratio
回流三氟乙酸(TFA)中的1-,2-和3-单取代的1,2,3,4,6,7,12,12b-八氢吲哚[2,3- a ]喹啉嗪烷基衍生物的酸催化差向异构化导致C-12b非对映异构体的平衡混合物。除非取代基在C-1上,否则热力学上更稳定的差向异构体比动力学上有利的差向异构体的比例大约为85:15,在这种情况下比例为55:45。当在回流的TFA- d中进行差向异构化时,C-12b处的质子被交换。描述了缺失的2-乙基吲哚并[2,3- a ]喹啉二叠氮烷的新的立体选择性合成。
Stereochemical course of the alkaline decarboalkoxylative cyclization of C(4)- C(5)- and C(4) ,C(5)-substituted 1-[2-(3-indolyl)ethyl-3-methoxycarbonyl -1,4,5,6-tetrahydropyridines to C(2)- , C(3)- and C(2) ,C(3)-substituted indolo[2,3-a quinolizidines
Alkaline decarboalkoxylative cyclization of C(4)-monosubstituted 1-[2-(3-indolyl) ethyl-3methoxycarbonyl-1,4,5,6-tetrahydropyridines 1a and 1d leads mainly to C(2)-monosubstituted indolo[2,3-a quinolizidines 2a and 2d possessing the C(12b)H-C(2)H cis relationship [corresponding to the C(3)H-C(15)H cis relationship when the biogenetic numbering of indole alkaloids is used
Our recently developed method is successfully applied to the preparation of 1- and 3-monosubstituted 1,2,3,4,6,7,12,12b-octahydroindolo[2,3-]quinolizines possessing the C(12b)H-C(1)H and C(12b)H-C(3)H relationship, respectively, or at will. Complete 13C NMR data are presented for the prepared compounds.
我们最近开发的方法已成功地用于制备具有C(12b)HC(1)的1-和3-单取代的1,2,3,4,6,7,12,12b-八氢吲哚[2,3- ]喹喔啉)H和C(12b)HC(3)H关系,或随意。提供了所制备化合物的完整13 C NMR数据。
Studies on the synthesis of the indole alkaloids ngouniensine and epingouniensine
Tetracyclic keto lactam 2a has been synthesized by acyladon of a mixture of esters 5, followed by saponification and further cyclization. Due to the presence of an exocyclic amide carbonyl group, epimerization at C-3 occurs to give the most stable cis relative configuration. Trans acetylpiperidine 4b has been prepared in five steps from pyridinium salt 9. Attempted direct cyclization of 4b to epingouniensine