Nomenclature of Lignans and Neolignans

These Rules are as close as possible to the published version [see Pure Appl. Chem., 2000, 72, 1493-1523; reproduced with the permission of IUPAC and IUBMB]. If you need to cite these rules please quote this references as their source.

A PDF of these recommendations is available.

German translation see Angew. Chem., 2005, 117, 2339-2351.

Any comments should be sent to any member of the Committee

This document was prepared by G. P. Moss in collaboration with P. K. Agrawal (India), D. C. Ayres (UK), E. Brown (France), J. R. Bull (South Africa), J. R. Cole (USA), P. M. Dewick (UK), J. M. Fang (Taipei), S. F. Fonseca (Brazil), O. R. Gottlieb (Brazil), Y. Kato (Japan), L. H. Klemm (USA), J. Mann (UK), A. Pelter (UK), R. Stevenson (USA), J. Van der Eycken (Belgium) and D. A Whiting (UK).

Abstract: Lignans and neolignans are a large group of natural products characterised by the coupling of two C₆C₃ units. For nomenclature purposes the C₆C₃ unit is treated as propylbenzene and numbered from 1 to 6 in the ring, starting from the propyl group, and with the propyl group numbered from 7 to 9, starting from the benzene ring. With the second C₆C₃ unit the numbers are primed. When the two C₆C₃ units are linked by a bond between positions 8 and 8' the compound is referred to and named as a lignan. In the absence of the C-8 to C-8' bond, and where the two C₆C₃ units are linked by a carbon-carbon bond it is referred to and named as a neolignan. The linkage with neolignans may include C-8 or C-8'. Where there are no direct carbon-carbon bonds between the C₆C₃ units and they are linked by an ether oxygen atom the compound is named as an oxyneolignan. The nomenclature provides for the naming of additional rings and other modifications following standard organic nomenclature procedures for naming natural products. Provision is included to name the higher homologues. The sesquineolignans have three C₆C₃ units and dineolignans have four C₆C₃ units.

Contents

• LG-0 Introduction
  • 0.1 Previous Proposals
  • 0.2 General Principles
• LG-1 Fundamental Parent Structures
  • 1.1 Lignane
  • 1.2 Neolignane
  • 1.3 Indicated Hydrogen
  • 1.4 Oxyneolignane
  • 1.5 Numbering of Lignane, Neolignane and Oxyneolignane Skeletons
• LG-2 Modification of the Fundamental Parent Structure
  • 2.1 Additional Carbocyclic Rings (the prefix cyclo-)
  • 2.2 Ring Cleavage (the prefix seco-)
  • 2.3 Removal of Skeletal Atoms (the prefix nor-)
  • 2.4 Addition of Skeletal Atoms (the prefix homo-)
  • 2.5 Replacement of Skeletal Atoms (the prefix oxa-, etc)
  • 2.6 Bridged Parent Structures (the prefix epoxy-, etc)
  • 2.7 Bond Migration (the prefix abeo-)
  • 2.8 Combination of Prefixes
• LG-3 Changes in Hydrogenation Level
  • 3.1 Unsaturation in the Side Chain
  • 3.2 Reduction of the Aromatic Ring
  • 3.3 Double Bonds Between the Aromatic Ring and Side Chain
• LG-4 Lignane, Neolignane and Oxyneolignane Derivatives
  • 4.1 Carboxylic Acids
  • 4.2 Lactones
  • 4.3 Esters
  • 4.4 Ketones
  • 4.5 Alcohols or Phenols
  • 4.6 Ethers and Alcohol or Phenol Derivatives
• LG-5 Stereochemistry
  • 5.1 Orientation of Formulae
  • 5.2 Configuration Symbols
  • 5.3 Absolute Configuration
  • 5.4 Relative Configuration
  • 5.5 Racemate
  • 5.6 Enantiomers
  LG-6 Trimers of the C₆C₃ Unit and Higher Analogues
  • 6.1 Sesquineolignans
  • 6.2 Dineolignans
• LG-7 Summary
• References