7577-74-4Relevant articles and documents
Competitive Pseudopericyclic [3,3]- and [3,5]-Sigmatropic Rearrangements of Trichloroacetimidates
Sharma, Shikha,Rajale, Trideep,Unruh, Daniel K.,Birney, David M.
, p. 11734 - 11743 (2015/12/11)
The Woodward-Hoffmann rules predict whether concerted pericyclic reactions are allowed or forbidden based on the number of electrons involved and whether the cyclic orbital overlap involves suprafacial or antarafacial orbital overlap. Pseudopericyclic reactions constitute a third class of reactions in which orthogonal orbitals make them orbital symmetry allowed, regardless of the number of electrons involved in the reaction. Based on the recent report of eight-centered ester rearrangements, it is predicted that the isoelectronic eight-centered rearrangements of imidates would also be allowed. We now report that these rearrangements occur, and indeed, an eight-centered rearrangement is slightly favored in at least one case over the well-known six-centered Overman rearrangements, in a trichloroacetimidoylcyclohexadienone, a molecular system where both rearrangements are possible.
Experimental and computational studies on the [3,3]- and [3,5]-sigmatropic rearrangements of acetoxycyclohexadienones: A non-ionic mechanism for acyl migration
Sharma, Shikha,Rajale, Trideep,Cordes, David B.,Hung-Low, Fernando,Birney, David M.
supporting information, p. 14438 - 14447 (2013/10/21)
Flash vacuum pyrolysis studies of substituted 6-acetoxy-2,4- cyclohexadienones (3 and 10) from 300 to 500 C provide strong experimental evidence that direct [3,5]-sigmatropic rearrangements in these molecules are favored over the more familiar [3,3]-sigma
Oxidation of o-isopropylphenol with lead tetraacetate: Synthesis of the unit of celastroidin terpenes by the Diels-Alder condensation
Jankowski,Savoie,Lesage,Boivin,Leclair,Diaz T,Reyes-Chilpa,Jimenez-Estrada,Barrios
, p. 429 - 440 (2007/10/03)
Lead tetraacetate oxidation of o-isopropyl phenol under various conditions led to the dienone acetate which, when dimerized, represents a central part of the celastroidin penta- and hexa-terpenes (natural products from the Mexican shrub Hippocratea Celastroides). Six oxidation products formed in this reaction (the iso-propyl dienolone acetate, two dimers, benzoquinone, and two phenol acetates) were identified with help of 2D and 3D NMR, GC and LC-MS. From this, we concluded that the dimer skeleton observed for the dienolone acetate in natural products corresponded to the product from the photochemical pathway, and that the synthetic dimer has the opposite geometry; this was verified by molecular modelling. The oxidation of the second compound, o-cresol, leads to a similar profile of products.
A solvolytic C-C cleavage reaction of 6-acetoxycyclohexa-2,4-dienones: Mechanistic implications for the intradiol catechol dioxygenases
Eley,Crowley,Bugg
, p. 2091 - 2097 (2007/10/03)
6-Acetoxycyclohexa-2,4-dienones are found to undergo a rapid reaction in methanol/water under mildly basic conditions to give an acyclic ketoester as the major product for 6-phenyl and 6-methyl substrates. Reaction monitoring by UV spectroscopy indicates
PHOTOLACTONIZATION : A NOVEL SYNTHETIC ENTRY TO MACROLIDES
Quinkert, Gerhard,Billhardt, Uta-Maria,Jakob, Harald,Fischer, Gerd,Glenneberg, Juergen,et al.
, p. 822 - 861 (2007/10/02)
o-Quinol acetates, hydroxyalkyalted at C(6), are easily accesible from simple phenols by Wessely acetoxylation (preferentially catalyzed by BF3).On UV irradiation ( in the presence of an appropriate tertiary amine), they are smoothly converted to macrocyclic lactones.Subtle conditions have been elaborated to lead to high overall yields, and the scope of the conversion of phenols to macrolides has been elucidated.
