2738-25-2Relevant articles and documents
STEREOSPECIFICITY IN THE PICTET-SPENGLER REACTION. ENANTIOSPECIFIC SYNTHESIS OF (6S,10S)-(-)-5-METHYL-9-OXO-12-BENZYL-6,7,8,9,10,11-HEXAHYDRO-6,10-IMINO-5H-CYCLOOCTINDOLE, A TEMPLATE FOR PREPARATION OF MACROLINE/SARPAGINE ALKALOIDS
Zhang, Lin-Hua,Bi, Ying-Zhi,Yu, Fu-Xiang,Menzia, Gerald,Cook, James M.
, p. 517 - 547 (2007/10/02)
The synthesis of the tetracyclic ketone was carried out in enantiospecific fashion (>98percent ee) via the 1,3-transfer of chirality from Na-methyl, Nb-benzyl tryptophan methyl ester to the trans diastereomer in the Pictet-Spengler reaction.Although the condensation of 14 with aldehyde (15) in refluxing benzene generated the tetrahydro β-carbolines (4b/5b) in a kinetic ratio (72:28), epimerization (C-1) of the cis diastereomer into the trans isomer occurred stereospecifically under acidic conditions.Dieckmann cyclizatin of either the Na-methyl, Nb-benzyl-cis-(+)-5b or trans-(-)-4b diastereomer provided the cis-bicyclo-azanonane system at approximately the same rate, although the β-keto esters were antipodal, in contrast to results reported in the Na-benzyl series by Magnus.
PICTET-SPENGLER REACTIONS IN APROTIC MEDIA. Nb-BENZYL PROMOTED RETENTION OF OPTICAL ACTIVITY IN THE SYNTHESIS OF AN INDOLO SUBSTITUTED AZABICYCLONONANE, A KEY TEMPLATE FOR THE SYNTHESIS OF MACROLINE ALKALOIDS.
Zhang, Lin-hua,Cook, James M.
, p. 2795 - 2802 (2007/10/02)
The Nb-benzyl group (see 7) has been employed in the Pictet-Spengler reaction in refluxing benzene to provide complete retention of optical activity in this process.The tetrahydro-β-carbolines 3b (trans) and 4b (cis) were independently converte
Selenium Dioxide Oxidations in the Indole Area. Synthesis of β-Carboline Alkaloids
Cain, M.,Campos, O.,Guzman, F.,Cook, J.M.
, p. 907 - 913 (2007/10/02)
A number of different piperidoindole systems have been subjected to oxidation with selenium dioxide.The bonding between the indole and piperidine unit has been varied to provide different systems, the oxidation of which has led to formation of either 2-acyl- or 3-acylindoles or fully aromatic β-carbolines, depending on the substrate chosen.The pattern of reactivity observed was in complete agreement with the ene mechanism proposed for selenium dioxide oxidations, and this can be employed to predict the regiochemistry of the oxidation.Use of this technology has resulted in a two-step synthesis of the indole alkaloid canthin-6-one (30a).