Pictet-Spengler reaction catalyzed by cyanuricchloride (trichloro-1,3,5-triazine, TCT) is described. The 6-endo cyclization of tryptophan/tryptamine and modified Pictet-Spengler substrates with both electron-withdrawing and electron-donating aldehydes was carried out by using a catalytic amount of TCT (10 mol %) in DMSO under a nitrogen atmosphere. TCT catalyzed the Pictet-Spengler reaction involving electron-donating
A mild and efficient protocol for the Pictet-Spengler reaction in water using an acid catalyst has been described. The condensation of tryptophan, tryptamine, and N-b-benzyl tryptophan with different aldehydes having both electron-withdrawing and -donating substituents in the presence of a catalytic amount of TFA in water furnished tetrahydro-beta-carbolines in good isolated yields. A salient feature of the water mediated Pictet-Spengler reaction was the general trend observed during the condensation of Trp-OMe and aryl/aliphatic aldehydes furnishing diastereomeric mixtures with a preference for the cis-isomer. (c) 2007 Elsevier Ltd. All rights reserved.
Application of chlorotrimethylsilane in Pictet–Spengler reaction
作者:Sergey V. Ryabukhin、Dmitriy M. Panov、Andrey S. Plaskon、Andrey A. Tolmachev、Radomyr V. Smaliy
DOI:10.1007/s00706-012-0804-7
日期:2012.11
Chlorotrimethylsilane has been found to be an efficient condensing agent in the Pictet-Spengler reaction, affording an extremely straightforward synthetic route to tetrahydro-beta-carboline derivatives and their analogs. The applicability of the method has been studied, and a representative library of structurally diverse products has been created..
Organic base-promoted efficient dehydrogenative/decarboxylative aromatization of tetrahydro-β-carbolines into β-carbolines under air
DBN has been identified as an efficient reagent for promoting the dehydrogenative/decarboxylative aromatization of tetrahydro-β-carbolines under air atmosphere, to access the corresponding β-carbolines in moderate to good yields. The utility of this protocol for the gram-scale synthesis of β-carboline alkaloids eudistomin U (7) and harmane (10) has also been demonstrated.