Absolute configuration of methyl isoeichlerialactone
Abstract:
The title compound, C(28)H(44)O(4)·0.56H(2)O, is a co-crystal of methyl isoeichlerialactone monohydrate as the major component and methyl isoeichlerialactone as the minor component in a 0.55778 (3):0.44222 (3) ratio. The conformations of both components are identical except for that of the -COOCH(3) group of the methyl propanoate side chain on the cyclo-hexane ring which is positionally disordered over two orientations. The mol-ecule of methyl isoeichlerialactone has three fused rings and all rings are trans-fused. The two cyclo-hexane rings are in standard chair conformations and the cyclo-pentane ring adopts an envelope conformation. In the crystal, weak C-H⋯O inter-actions link methyl isoeichlerialactone mol-ecules into screw chains along [010]. The crystal structure is further stabilized by O-H⋯O hydrogen bonds and weak C-H⋯O inter-actions.
Related Concept Videos
Isomerism in Alkenes
An isomer is called cis-2-butene when the methyl groups are on the same side of the double bond, and the other stereoisomer, in which methyl groups are on the opposite side of the double bond, is called trans-2-butene. The cis and trans stereoisomers are not...
Stereoisomerism of Cyclic Compounds
Disubstituted Cyclohexanes: cis-trans Isomerism
In cyclohexane, the substituents can occupy different positions generating distinct isomers.
Stability of Substituted Cyclohexanes
The two chair conformations of cyclohexanes undergo rapid interconversion at room temperature. Both forms have identical energies and stabilities, each comprising equal amounts of the equilibrium mixture. Replacing a hydrogen atom with a functional group makes the two conformations energetically non-equivalent.
For example, in...
Isomerism
[3,3] Sigmatropic Rearrangement of Allyl Vinyl Ethers: Claisen Rearrangement


