Please use this identifier to cite or link to this item:
http://hdl.handle.net/2080/515
Title: | A Sequential Pummerer-Diels-Alder Route for the Generation and Trapping of Furo[3,4-c]pyridines: Synthesis of Heterocyclic Analogues of 1-Arylnaphthalene Lignans |
Authors: | Sarkar, T K Panda, Niranjan Basak, S |
Issue Date: | 2003 |
Publisher: | American Chemical Society |
Citation: | Journal of Organic Chemistry, Vol 68, Iss 18, P 6919-6927 |
Abstract: | The Pummerer reaction of an o-benzoyl-substituted pyridylmethyl sulfoxide generates an -thiocarbocation, the interception of which by a neighboring keto functionality produces an -thio-substituted furo[3,4-c]pyridine as transient intermediate; the latter undergoes a Diels-Alder cycloaddition with an added dienophile. Base-induced ring opening of the cycloadduct followed by aromatization gives an isoquinoline derivative that may be looked upon as a heterocyclic analogue of 1-arylnaphthalene lignans. This procedure occurs readily with electron-poor dienophiles and the entire sequence can be run in one pot. The facility of the sequential Pummerer-Diels-Alder reaction hinges on the experimental conditions, the best results being obtained with heptafluorobutyric anhydride as the triggering agent in toluene containing a catalytic amount of p-toluenesulfonic acid. In the absence of a dienophile it is possible to isolate and characterize a rather unstable furo[3,4-c]pyridine derivative. An intramolecular variant of this protocol is also feasible with use of unactivated alkenyl tethers of variable length; however, the bridged cycloadducts are unisolable in these cases as they undergo spontaneous ring opening and aromatization to yield cycloalka[h]isoquinolines. The usefulness of the sequential Pummerer-Diels-Alder reaction is further demonstrated through the synthesis of a heterolignan with a built-in lactone ring via oxidation of the initial [4+2]-cycloadduct followed by extrusion of phenyl sulfinate and elaboration of the resulting hydoxylated isoquinoline derivative |
Description: | Copyright for the published version belongs to American Chemical Society |
URI: | http://dx.doi.org/10.1021/jo0344081 S0022-3263(03)04408-6 http://hdl.handle.net/2080/515 |
Appears in Collections: | Journal Articles |
Files in This Item:
File | Description | Size | Format | |
---|---|---|---|---|
niranjanACS.pdf | 24.39 kB | Adobe PDF | View/Open |
Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.