Bioinspired Syntheses of the Pyridoacridine Marine Alkaloids Demethyldeoxyamphimedine, Deoxyamphimedine, and Amphimedine
摘要:
Efficient bioinspired syntheses of the biologically active pyridoacridine marine alkaloids demethyldeoxyamphimedine, deoxyamphimedine, and amphimedine are reported. Reaction of styelsamine D, prepared via an optimized route starting from Boc-dopamine, with paraformaldehyde afforded demethyldeoxyamphimedine and deoxyamphimedine. Oxidation of the latter using either K-3[Fe(CN)(6)] or DMSO/conc. HCl gave amphimedine in 8 steps from tryptamine with an overall yield of 14%. The versatility of the method was demonstrated by the synthesis of non-natural ethyl and benzyl congeners of deoxyampbimedine and amphimedine.
The asymmetric catalytic synthesis of 3-cyclotryptamine substituted oxindoles through formal [4 + 2] cycloaddition/cyclization cascade is described. A wide range of cyclotryptamine derivatives were obtained in enantioenriched form under mild reaction conditions and were found to have potential anticancer activity. The strategy enables ready assembly of cyclotryptamine subunits at the C3a–C3a′ positions
描述了通过正式的[4 + 2]环加成/环化级联反应3-环色胺取代的羟吲哚的不对称催化合成。在温和的反应条件下,以对映体富集的形式获得了广泛的环色胺衍生物,发现它们具有潜在的抗癌活性。该策略使C 3a – C 3a'位置的环色胺亚基易于组装,并具有两个四级立体异构中心,具有顺式选择性,从而可以合成光学活性的顺式双(六氢吡咯并吲哚)和环色胺生物碱家族的其他化合物。
Highly Enantioselective Tandem Michael Addition of Tryptamine-Derived Oxindoles to Alkynones: Concise Synthesis of Strychnos Alkaloids
to alkynones was developed by taking advantage of a chiral N,N′‐dioxide Sc(OTf)3 catalyst. The reaction enables the facile preparation of enantioenriched spiro[pyrrolidine‐3,3′‐oxindole] compounds, which provides a novel strategy for the synthesis of monoterpenoid indole alkaloids. As a demonstration, the asymmetric synthesis of strychnos alkaloids [(−)‐tubifoline, (−)‐tubifolidine, (−)‐dehydrotubifoline]
An operationally simple photochemical strategy for the direct arylation of oxindoles with (hetero)arylhalides in the absence of both transition metals and photoredox catalysts has been developed. The reaction provides an efficient way to construct various 3-aryloxindole building blocks of pharmaceutical interest at ambient temperature by using household compact fluorescent light (CFL) bulbs as the
Enantioselective Steglich Rearrangement of Oxindole Derivatives by Easily Accessible Chiral <i>N</i>,<i>N</i>-4-(Dimethylamino)pyridine Derivatives
作者:Hiroki Mandai、Takuma Fujiwara、Katsuaki Noda、Kazuki Fujii、Koichi Mitsudo、Toshinobu Korenaga、Seiji Suga
DOI:10.1021/acs.orglett.5b02089
日期:2015.9.18
Chiral N,N-4-(dimethylamino)pyridine (DMAP) derivatives, which can be readily prepared by the Ugi multicomponent reaction in a one-pot manner, have been efficiently applied to the enantioselective Steglich rearrangement of oxindole derivatives to give the desired products bearing a quaternary carbon center in high yield (>98% yield) and with high enantioselectivity (up to 99:1 er).
Regioselective oxidation of indoles to 2-oxindoles
作者:Santosh V. Shelar、Narshinha P. Argade
DOI:10.1039/c9ob00764d
日期:——
Facile regioselective oxidation of indoles to 2-oxindoles promoted by sulfuric acid adsorbed on silica gel is reported. The demonstrated practical site-selective heterogeneous oxidation reactions conveniently take place with a broad substrate scope and functional group tolerances. The present oxidation strategy is also employed to accomplish the total synthesis of natural products donaxaridine and