Petasis-Ferrier-type rearrangement

The catalytic cycle and stereochemical preferences of a stoichiometric variant of the Petasis-Ferrier rearrangement were recently thoroughly studied computationally This enabled the computational study of the reaction catalyzed by chiral BlNOL-based phosphoric acids.  

Computations showed that during the whole transformation the bond lengths of two oxygen atoms of the PO4 unit that are involved in the coordination with the substrate remain the same and approximately equal (1.47-1.50 A). Thus, the phosphoric acid releases a proton as an anionic conjugate base, and the resultant negative charge is delocalized over the phosphoric acid moiety. As a result, the interaction between the catalyst and the 

the stereoselection in the Petasis-Ferrier-type rearrangement catalyzed by chiral phosphoric acids is based according to this study on a subtle interplay of the nonconventional weak interactions. The importance of the aldehyde C-H...O hydrogen bonding has been earlier suggested in various transformations catalyzed by chiral phosphoric acids.  

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A chiral phosphoric acid-catalyzed Petasis-Ferrier-type rearrangement of a seven-membered cyclic vinyl acetal resulted in the formation of a chiral tetrahydrofuran species. It was found that nonclassical hydrogen bonds between the catalyst and the substrate play an important role in controlling the stereoselectivity (14CS3515). 

Kanomata, K. Toda, Y. Shibata, Y. Yamanaka, M. Tsuzuki, S. Gridnev, I. D. Terada, M. Secondary Stereocontrolling Interactions in Chiral Bronsted Acid Catalysis Study of a Petasis-Ferrier-Type Rearrangement Catalyzed by Chiral Phosphoric Acids. Chem. Sci. 2014,5,3515-3523. 

Similarly, the C22-C26 fully substituted central tetrahydropyran ring of phorboxazole was prepared using the modified Petasis-Ferrier rearrangement. Based on the known mechanistic model, the enol acetal moiety of the rearrangement substrate required the (Z)-configuration. The synthesis of this enol ether was not possible with either the Takai- or Petasis-Tebbe oiefinations. Utilization of the Type-ll Julia olefination afforded the desired enol acetal, but with no /Z selectivity. Upon treatment of these enol ethers with Me2AICI, the rearrangement afforded only the desired tetrahydropyran in excellent yield. 

The aza-Petasis-Ferrier rearrangement is not a true concerted sigmatropic reaction, since it is thought to proceed via C-O bond cleavage of a hemiaminal vinyl ether by the action of an acid catalyst to afford a reactive iminium cation and the enol form of an aldehyde these two intermediates combine subsequently in a Mannich-type process, leading to 3-amino aldehydes (Scheme 40.45) [54]. Recently, Terada and Toda used a BINOL-derived phosphoric acid diester as a catalyst for this interesting reaction [55]. 

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