A convenient preparation of 3-isopropyl-1-methylcyclopentylmethanol and 1-isopropyl-3-methylcyclopentylmethanol via Favorskii rearrangement

The Favorskii rearrangement of suitable α-chloro derivatives of commercially available (+)- and (−)-carvone, and (−)-menthone served efficiently to prepare the title compounds featuring delicious fruity, floral olfactory notes.

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[(1R,3R)-3-Methyl-1-isopropylcyclopentyl]-methanolC10H20O[α]D25=+10.9 (c 1, CHCl3)Source of chirality: (2S,5R)-(−)-menthoneAbsolute configuration: (1R,3R)

[(1R,3S)-3-Isopropyl-1-methylcyclopentyl]-methanolC10H20O[α]D25=-11.4 (c 1, CHCl3)Source of chirality: (S)-(+)-carvoneAbsolute configuration: (1R,3S)

Methyl (1R,3S)-3-isopropyl-1-methyl-cyclopentanecarboxylateC11H20O2[α]D25=-7.8 (c 1, CHCl3)Source of chirality: (S)-(+)-carvoneAbsolute configuration: (1R,3S)

Methyl (1S,3R)-1-isopropyl-3-methyl-cyclopentanecarboxylateC11H20O2[α]D25=-16.3 (c 1, CHCl3)Source of chirality: (2S,5R)-(−)-menthoneAbsolute configuration: (1S,3R)

Methyl (1R,3R)-1-isopropyl-3-methyl-cyclopentanecarboxylateC11H20O2[α]D25=+3.8 (c 1, CHCl3)Source of chirality: (2S,5R)-(−)-menthoneAbsolute configuration: (1R,3R)

[(1S,3R)-3-Methyl-1-isopropylcyclopentyl]-methanolC10H20O[α]D25=+15.6 (c 1, CHCl3)Source of chirality: (2S,5R)-(−)-menthoneAbsolute configuration: (1S,3R)