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首页> 外文期刊>Chemistry: A European journal >Solid-phase synthesis of tetrahydro-beta-carbolines and tetrahydroisoquinolines by stereoselective intramolecular n-carbamyliminium Pictet-Spengler reactions
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Solid-phase synthesis of tetrahydro-beta-carbolines and tetrahydroisoquinolines by stereoselective intramolecular n-carbamyliminium Pictet-Spengler reactions

机译：立体选择性分子内n-氨基甲酰基亚胺Pictet-Spengler反应固相合成四氢-β-咔啉和四氢异喹啉

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摘要

A solid-phase method for the synthesis of tri-, tetra-, and pentacyclic compounds containing tetrahydro-beta-carboline, tetrahydroisoquinoline or analogous scaffolds is presented. The reaction proceeds with high stereoselectivity through an intermediate N-carbarnyliminium ion that exclusively converts into Pictet-Spengler-type products with a variety of C-nucleophiles. Amino aldehydes masked with 3-Boc-(1,3)-oxazinane (Box) have been synthesized from amino acids, amino alcohols, or 2-nitro benzaldehydes. The amino moiety of these masked aldehydes has been converted into pentafluorophenyl carbarnate to serve as a urea precursor. The building blocks were incorporated at the N-terminal of a resin-supported dipeptide through urea formation. Subsequent treatment with acid liberated the aldehyde quantitatively. A penultimate tryptophan residue gave rise, under the acetic conditions, to a spontaneous intramolecular Pictet-Spengler reaction with the liberated aldehyde. The reaction proceeded with a high degree of stereoselectivity affording tetrahydro-beta-carbolines with a de (de=diastereomeric excess) above 95% and purity in the range of 90-99%. This reaction has been extended to a range of other aromatic C-nucleophiles, including substituted indoles, benzenes, pyrene, furan, thiophenes, and benzothiophene with comparable stereoselectivity and purity. Prolonged exposure of the benzaldehyde-derived Pictet-Spengler products to strong acid and air lead to quantitative auto-oxidation which yielded compounds with a 3,4-dihydro-beta-carboline, a 3,4-dihydroisoquinoline, or a similar core structure.
机译：提出了一种固相方法，用于合成包含四氢-β-咔啉，四氢异喹啉或类似骨架的三环，四环和五环化合物。反应通过中间体N-氨基甲酰基亚胺离子以高立体选择性进行，该中间体仅转化为具有各种C-亲核试剂的Pictet-Spengler型产物。由氨基酸，氨基醇或2-硝基苯甲醛合成了被3-Boc-（1,3）-恶嗪烷（Box）掩盖的氨基醛。这些被掩盖的醛的氨基部分已被转化为五氟苯基碳酸盐，以用作尿素前体。通过尿素形成，将结构单元掺入树脂负载的二肽的N-末端。随后用酸处理定量地释放醛。倒数第二个色氨酸残基在乙酸条件下与释放的醛发生自发的分子内Pictet-Spengler反应。反应以高度的立体选择性进行，得到四氢-β-咔啉，其de（de ＝非对映体过量）超过95％，纯度在90-99％的范围内。该反应已扩展到其他芳族C-亲核试剂，包括取代的吲哚，苯，pyr，呋喃，噻吩和苯并噻吩，具有相当的立体选择性和纯度。苯甲醛衍生的Pictet-Spengler产品长时间与强酸和空气接触会导致定量自动氧化，从而产生具有3,4-二氢-β-咔啉，3,4-二氢异喹啉或类似核心结构的化合物。

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