138152-09-7Relevant academic research and scientific papers
Simple metal salts supported on montmorillonite as recyclable catalysts for intramolecular hydroalkoxylation of double bonds in conventional and VOC-exempt solvents
Notar Francesco, Irene,Cacciuttolo, Bastien,Pucheault, Mathieu,Antoniotti, Sylvain
supporting information, p. 837 - 841 (2015/03/04)
We describe herein an efficient and particularly sustainable catalytic system for the intramolecular hydroalkoxylation of double bonds. A heterogeneous catalyst based on the impregnation of benign metals such as iron and bismuth on montmorillonite was used for a highly atom-economic transformation in DMC, a non-VOC solvent. The transformation allowed the formation of a large range of cyclic ethers from the corresponding unsaturated alcohols and the catalyst could be recycled several times.
Internal Nucleophilic Termination in Biomimetic Acid Mediated polyene Cyclizations: Stereochemical and Mechanistic Implications. Synthesis of (+/-)-Ambrox and Its Diastereoisomers
Snowden, Roger L.,Eichenberger, Jean-Claude,Linder, Simon M.,Sonnay, Philippe,Vial, Christian,Schulte-Elte, Karl H.
, p. 955 - 960 (2007/10/02)
Treatment of 10 structurally releted trienols and dienols 5-8 with an excess of fluorosulfonic acid in 2-nitropropane at -90 deg C afforded, in 74-87percent yield, diastereoisomeric mixtures of the odoriferous norlabdane oxides 9-15 ((-)-9 (Ambrox) is a naturally occuring ambergris odorant).These tranformations represent examples of efficientbiomimetic acid-mediated cyclizations in which the hydroxyl group serves as the internal nucleophilic terminator.The stereochemical outcome of these kinetically controlled processes has been analysed in detail, and mechanistic hypotheses consistent with the results have been proposed.For the four acyclic trienols 5, the major reaction pathway can be rationalized by a totally synchronous process involving three internal anti additions via chair or skew-boat conformations of the nascent cyclohexane rings.An alternative explanation postulates a nonsynchronous process in which ring closure to an intermediate cyclohexyl cation is followed by rapid cyclization, directed by a strong kinetic preference for equatorial C-C and C-O bond formation.In contrast, for the monocyclic dienols 6-8 only a nonsynchronous process, involving prior protonation of the cyclohexenyl bond, is fully consisitent with the results.In the nonsynchronous processes, the orientation of the side chain vicinal to the cyclohexyl cation directs the stereochemical course of the cyclization.For the acyclic trienols, this factor is predetermined by the configuration of the C(7)=C(8) bond, whereas, for the monocyclic dienols, this orientation is determined by the stereoselective axial protonation of the cyclohexenyl bond in 6, or by the distribution of cyclohexene and cyclohexane conformers in 7 and 8, respectively.In the cases studied, it is clear that conformational inversion of the six-membered ring is slower than cyclization and thus ensures that an equatorial side chain leads to a trans A/B ring junction in the cyclization product, whereas an axial side chain affords a cis A/B ring junction.
