80041-00-5Relevant articles and documents
Exploiting the vicinal disubstituent effect on the diastereoselective synthesis of γ and δ lactones
Brenna, Elisabetta,Dalla Santa, Francesco,Gatti, Francesco G.,Gatti, Giuseppe,Tessaro, Davide
, p. 813 - 821 (2019/02/01)
Trifluoroacetic acid catalysed lactonization of vicinal disubstituted γ-hydroxyesters was investigated in different solvents. The reaction kinetics, monitored by NMR spectroscopy, showed that: (i) the vic-disubstituent effect is stereoselective since the anti diastereoisomer ring closes substantially more rapidly than the syn isomer ring; (ii) the anti-vic effect is much stronger than the classical Thorpe-Ingold effect (known also as the gem-disubstituent effect), instead the syn diastereoisomers have rate constants comparable to that of the gem-disubstituted ester; (iii) the vic-effect can be enhanced by increasing the steric hindrance of one of the two substituents or carrying out the reaction in non-polar solvents. DFT computations of energy barriers (ΔG?) were in good agreement with the experimental data. The distortion/interaction-activation strain model together with the Winstein-Holness kinetic scheme gave more insights into the origin of the vic-effect. An application of this effect consists of the diastereomeric resolution of disubstituted γ and δ lactones, among which are the naturally occurring Nicotiana t. lactone, the whisky and cognac oak lactones, and the Aerangis lactone. Both cis and trans diastereoisomers of these lactones were isolated in good yield and with high diastereomeric excess (de >92%). The selectivities of the diastereomeric resolution process, determined by NMR spectroscopy, are reported as well.
An expedient synthesis of olfactory lactones by intramolecular hydroacylalkoxylation reactions
Adrio, Luis A.,Hii, King Kuok Mimi
, p. 1852 - 1857 (2011/05/05)
A series of 4,5-disubstituted γ-lactones, including whisky and cognac lactones, was synthesised in four steps from a readily available chiral precursor. By using an intramolecular hydroacylalkoxylation reaction in the final step, a correlation between the (E)/(Z) configuration of the precursor and the product distribution has been established, for the first time, in this type of cyclisation reactions. Copyright
Oxidative rearrangement of 2-alkoxy-3,4-dihydro-2H-pyrans: stereocontrolled synthesis of 4,5-cis-disubstituted tetrahydrofuranones including whisky and cognac lactones and crobarbatic acid
Armstrong, Alan,Ashraff, Cassim,Chung, Hunsuk,Murtagh, Lorraine
experimental part, p. 4490 - 4504 (2009/10/09)
Oxidation of 2-alkoxy-3,4-dihydro-2H-pyrans 3 with dimethyldioxirane or MTO/urea-H2O2 followed by Jones oxidation leads to rearrangement and stereocontrolled formation of 4,5-cis-disubstituted tetrahydrofuranones. The method is applied to the synthesis of the whisky lactone 9, cognac lactone 10 and crobarbatic acid 17.