A Mnemonic for the Inositols

• Terence J. Painter ^[1]
  1. [1] University of Trondheim, Norway
• Localización: Journal of chemical education, ISSN 0021-9584, Vol. 73, Nº 10 (October), 1996, págs. 949-950
• Idioma: inglés
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• Resumen

  • The mnemonic derives from the mythical tale of Scylla and Charybdis in Homer's Odyssey (chapter 12). It takes the form of an imaginary headline in a newspaper: SCYLLA MEETS CHARYBDIS - EPIC NEWS MUCH ALARMS SICILY. The first two or three letters in each of these eight words remind the user that the nine configurational prefixes are scyllo-, meso-, (or myo-), chiro- [(+) and (-)], epi-, neo-, muco-, allo-, and cis-, respectively. The mnemonic also arranges the prefixes in an order that allows the configurations to be derived in a logical manner by performing a defined sequence of imaginary configurational inversions (epimerizations) around a cyclohexane ring. The all-equatorial, chair conformation of scyllo-inositol is selected as the starting point, and the sequence of inversions is defined by a systematic permutation of possibilities for performing one, two or three inversions in succession (1; 1 and 2; 1 and 3; 1 and 4; 1, 2 and 3; 1, 2 and 4; and finally 1, 3 and 5). In the case of the two chiro-inositols, the enantiomeric form is determined simply by the direction (clockwise or counterclockwise) around the ring in which the imaginary inversions are performed. This also applies formally to allo-inositol, but in that case the two optical enantiomers are isoenergetic chair conformers in rapid equilibrium.