13 research outputs found
2,2,9-Trimethyl-2,3-dihydropyrano[2,3-a]carbazol-4-(11H)-one
The title compound, C18H17NO2, was prepared from 1-hydroxy-7-methylcarbazole and 3,3-dimethylacrylic acid with trifluoroacetic acid as the cyclization catalyst. The molecules contain an essentially planar 6-methylindole unit. The second aromatic ring is significantly bent away from the plane of this unit, with maximum deviations of 0.171 (1) and 0.185 (1) Å for two of the C atoms. In the crystal structure, there are neither N—H⋯O hydrogen bonds nor π–π stacking between the aromatic sections of neighboring molecules. There is only one weak C—H⋯O hydrogen bond and a number of weak C—H⋯π interactions
2,2,10-Trimethyl-2,3-dihydropyrano[2,3-a]carbazol-4(11H)-one
The title compound, C18H17NO2, was prepared from 1-hydroxy-8-methylcarbazole and 3,3-dimethylacrylic acid with trifluoroacetic acid as the cyclization catalyst. Due to the –CMe2– group, the molecule is not quite planar. The packing is dominated by the strong N—H⋯O hydrogen bonds and some weaker C—H⋯O and C—H⋯π interactions. π–π Stacking interactions [centroid–centroid separation = 3.806 (2) Å] join neighboring molecules into loosely connected inversion dimers
1-(1-Hydroxy-9H-carbazol-2-yl)-3-methylbut-2-en-1-one
The title compound, C17H15NO2, was prepared as one of two products of the AlCl3/POCl3-catalysed reaction of 9-carbazol-1-ol with 3,3-dimethyacrylic acid. It crystallizes with two crystallographically independent molecules, A and B, which are virtually superimposable but not related by any translational or other pseudosymmetry. Both independent molecules are almost planar [r.m.s. deviations from planarity = 0.053 (1) and 0.079 (1) Å in A and B, respectively] and contain an intramolecular O—H⋯O hydrogen bond. Each type of molecules is connected via pairs of N—H⋯O hydrogen bonds, forming centrosymmetric A
2 and B
2 dimers which are, in turn, arranged in offset π-stacks extending along the a-axis direction. The offset of the dimers and the tilt angle of the molecules allows the formation of alternating C—H⋯π interactions between A and B molecules of parallel stacks
7,8,9,10-Tetrahydro-2-methylcyclohepta[b]indol-6(5H)-one
The title compound, C14H15NO, was synthesized from 2-hydroxymethylenecycloheptanone via a Japp–Klingemann acid-catalyzed cyclization. The seven-membered ring exhibits a slightly distorted envelope conformation. N—H⋯O hydrogen bonds form a centrosymmetric dimer; C—H⋯O hydrogen bonds and π–π stacking interactions (the centers of the atoms involved in the stacking interaction are separated by 3.504 Å) give rise to another type of centrosymmetric dimer. In combination, these interactions create a stair-like chain of molecules that interacts only loosely with neighboring chains via van der Waals interactions and weak C—H⋯π contacts
Total synthesis of the indole alkaloids henrycinol A and B
The total synthesis of new indole alkaloids henrycinol A and B were accomplished starting from L-tryptophan methyl ester. The key step is a stereochemically flexible Pictet-Spengler reaction governed by the presence or absence of an N-allyl group in the tryptophan precursor. The natural products henrycinol A and B were synthesized in good overall yield in eight and nine steps, respectively. (C) 2014 Elsevier Ltd. All rights reserved
2,2-Dimethyl-2,3-dihydropyrano[2,3-a]carbazol-4(11H)-one
The title compound, C17H15NO2, was prepared from 1-hydroxycarbazole and 3,3-dimethylacrylic acid with a mixture of AlCl3 and POCl3 as the cyclization catalyst. Owing to the presence of the –CMe2– group, the molecule is not quite planar. In the crystal structre, strong N—H...O hydrogen bonds and weaker C—H...π interactions occur, and a slipped π–π stacking interaction [centroid–centroid separation = 3.8425 (8) Å] is also observed