85923-52-0Relevant academic research and scientific papers
Methods for Indole Alkaloid Synthesis. A Specific Procedure for Introducing the 6,7 Double Bond into Aspidosperma-Type Alkaloids via Thiolactam Dehydrogenation
Magnus, Philip,Pappalardo, Paul A.
, p. 212 - 217 (2007/10/02)
Tetracyclic amides 6, 14, and 19 were converted into their corresponding thiolactam derivatives 7, 15, and 20 , respectively, by treatment with Lawesson's reagent.When these thiolactams were treated with p-toluenesulfinyl chloride/i-Pr2NEt/(0 deg C) followed by aqueous workup, the α,β-unsaturated thiolactams 8, 16, and 21 were isolated in good to excellent yields.S-Alkylation of the α,β-unsaturated thiolactams followed by reduction with NaBH4 gave the tetracyclic allylic tertiary amines 10, 17, and 22.Dealkylation could only be accomplished for the N-methyl system 22, and only in modest yield.The pentacyclic amide 28 was converted into the thiolactam 29 by treatment with Lawesson's reagent, followed by p-toluenesulfinyl chloride/i-Pr2NEt/65 deg C to give the α,β-unsaturated thiolactam 30 (92percent).Extension of this exceptionally mild dehydrogenation procedure to simple monocyclic thiolactams was not successful.A mechanistic rationale for this new procedure is described with an explanation for its unusual selectivity.
Indole-2,3-quinodimethanes: A New Strategy for the Synthesis of Tetracyclic Systems of Indole Alkaloids
Exon, Christopher,Gallagher, Timothy,Magnus, Philip
, p. 4739 - 4749 (2007/10/02)
The imine 7, derived from N--2-methylindole-3-carboxaldehyde (6) and 4-pentenylamine, on treatment with a range of chloroformates gave cis-octahydropyridocarbazoles 8, in yields ranging from 43 to 92percent.Similarly the series of imines 18-24 derived from 6 and the corresponding amine gave, on treatmnt with the mixed carbonyc anhydride from ethyl chloroformate and 4-pentenoic acid 25, the tetracyclic amides 26-31.The equivalent series of transformations with a 4a-ethyl group present leads directly to cis-fused tetracyclic precursors 40-42 and 45.The structure and relative stereochemistry of the tetracyclic carbamate 43 is confirmed by single-crystal X-ray crystallography.Some general examples of indole-2,3-quinodimethane cyclizations that give fused pentacyclic and spirocyclic compounds 49, 50, and 51 directly are described.
