119146-62-2Relevant articles and documents
Total synthesis of meloscine by a [2+2]-photocycloaddition/ring-expansion route
Selig, Philipp,Herdtweck, Eberhardt,Bach, Thorsten
experimental part, p. 3509 - 3525 (2010/01/11)
The unusual monoterpenoid indole alkaloid meloscine was synthesized starting from a protected aminoethylquinolone in 15 steps and an overall yield of 9%, employing a [2+2]-photocycloaddition as the stereochemistry defining key step. After the initial plan of a Wagner-Meerwein type rearrangement of a [4.2.0]- into a [3.3.0]-bicyclic substructure could not be realized, the required ring enlargement of a cyclobutane was eventually achieved by a retro-benzilic acid rearrangement. Generation of the central pyrrolidine ring was possible by a three-step reductive amination domino sequence. The final ring was built up by a ring-closing metathesis after the last quaternary stereocenter had been constructed by a Johnson-Claisen rearrangement. The synthesis was concluded by a selenylation-elimination sequence to build up the exocyclic vinyl group of meloscine. Using our methodology for enantioselective [2+2]-photocycloaddition mediated by a chiral complexation agent, the experimentally very simple synthesis could be performed in an enantioselective fashion (7% overall yield). The enantioselective synthesis of (+)-meloscine represents the first example of a natural product synthesis employing an enantioselective [2+2]-photocycloaddition as its key step, and illustrates nicely the synthetic potential of photochemical transformations for the construction of complex heterocyclic structures.
Uses of aza-cope rearrangement-mannich cyclization reactions to achieve a general entry to melodinus and aspidosperma alkaloids. stereocontrolled total syntheses of (±)-deoxoapodine, (±)-meloscine, and (±)-epimeloscine and a formal synthesis of (±)-1-acetylaspidoalbidine
Overmann, Larry E.,Robertson, Graeme M.,Robichaud, Albert J.
, p. 2598 - 2610 (2007/10/02)
The first total syntheses of the structurally unusual pentacyclic Melodinus alkaloids (±)-meloscine (1) and (±)-epimeloscine (2) and the hexacyclic Aspidosperma alkaloids (±)-deoxoapodine (4) are reported. The syntheses proceed via a highly functionalized common tetracyclic intermediate 7, which is accessed (with complete stereocontrol) by the title rearrangement of pyrindinol 10. These syntheses provide excellent examples of the power of tandem of aza-Cope rearrangement-Mannich cyclization reactions as the key element of stereocontrolled alkaloid synthesis design.
Total Synthesis of (+/-)-Meloscine and (+/-)-Epimeloscine
Overman, Larry E.,Robertson, Graeme M.,Robichaud, Albert J.
, p. 1236 - 1238 (2007/10/02)
Total syntheses of the Melodinus alkaloids (+/-)-meloscine and (+/-)-epimeloscine are reported.These are the first reported total syntheses of members of this structurally unique alkaloid class.
