Computational Investigation of Rearrangements in Huisgen Cycloadducts of Azolium <i>N</i>-Dicyanomethanide 1,3-Dipoles with Alkynes: A Mechanistic Panoply

Burke, Luke A.; Butler, R. N.

doi:10.1021/jo900063n

Cited by 5 publications

(7 citation statements)

References 79 publications

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“…The FVP of 19 and 23 was carried out on recrystallized solid samples. The compound to be pyrolyzed (19 or 23) was transferred into a quartz tube (65 cm long and 2 cm diameter) either directly as solid crystals or as a solution in diethyl ether (23) or acetone (19; due to its better solubility in acetone). The solvent was evaporated, and the compound was dried under high vacuum followed by purging the tube with nitrogen gas.…”

Section: ■ Conclusionmentioning

confidence: 99%

“…The 1 H NMR and 13 C NMR of 21 agreed with those reported in literature. 42,43 Synthesis of 1,2,4-Trimethyl-6-oxocyclohexa-2,4-dien-1-yl 2,2,2trichloroacetimidate ( 22) and 5,7,7a-Trimethyl-2-(trichloromethyl)-3a,7a-dihydrobenzo[d]oxazol-3a-ol (23). To a suspension of sodium hydride (∼27 mg, 1.05 mmol, 95% w/w) in dry THF (3 mL) was added a solution of starting alcohol 21 (200 mg, 1.32 mmol) in dry THF (2 mL) at −20 °C, and the mixture was allowed to stir at −20 °C for about 30 min.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

“…Since that time, there have been extensive efforts from our laboratory, − along with numerous insightful studies from other groups, both experimental , and computational, − exploring the scope of pseudopericyclic reactions. Aspects of this work have recently been reviewed, , and so only leading references to the extensive literature on these reactions are provided. − Four general characteristics have been suggested for pseudopericyclic reactions: ,, (1) planar, or close to planar transition states − ,− (2) low, or even nonexistent barriers, particularly when the transition state geometry is favorable, ,− ,− (3) nonaromatic transition states, ,,, and (4) perhaps most significantly and the focus of this work, no pseudopericyclic reaction can be forbidden. − ,, In particular, we have predicted , ...…”

Section: Introductionmentioning

confidence: 99%

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Competitive Pseudopericyclic [3,3]- and [3,5]-Sigmatropic Rearrangements of Trichloroacetimidates

et al. 2015

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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.

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Section: ■ Conclusionmentioning

confidence: 99%

Section: ■ Experimental Sectionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Competitive Pseudopericyclic [3,3]- and [3,5]-Sigmatropic Rearrangements of Trichloroacetimidates

et al. 2015

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“…Rablen [37] has reported that at some levels of theory, there are sequential transition structures on a symmetrical surface (as in Fig. 2) in the addition of dichlorocarbene to bicyclobutanes.…”

Section: Other Related Potential Energy Surfacesmentioning

confidence: 99%

Theory, Experiment and Unusual Features of Potential Energy Surfaces of Pericyclic and Pseudopericyclic Reactions with Sequential Transition Structures

Birney¹

2010

COC

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Recent computational and experimental studies of organic reactions that show sequential transition structures on the potential energy surfaces are reviewed. The specific focus is on pericyclic and pseudopericyclic reactions. A distinction is made between symmetric and unsymmetric systems; in the former, the intrinsic reaction coordinate connects the two transition structures. The importance of the change in the reaction coordinate for establishing the existence of the second transition structure and the influence of the energy of the second transition structure on the barrier height of the first and emphasized. In this latter context, corners on a reaction pathway are also significant. Lastly, the merging of two sequential transition structures is shown to give an "effective monkey saddle" transition structure.

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“…Burke and Butler examined the post-cycloaddition portion of the cascade shown in Scheme 37 using B3LYP calculations. 45 A variety of multi-step pathways involving a variety of different pericyclic reactions were found. Schreiner, Suffert and co-workers examined the origins of torquoselectivity observed experimentally in the fenestrane-forming 8-electron/6-electron electrocyclization cascades shown in Scheme 38 using B3PW91 calculations.…”

Section: Tandem and Hybrid Reactions Tandem Reactionsmentioning

confidence: 99%

Reaction mechanisms : Part (ii) Pericyclic reactions

Lee

Tantillo

2010

Annu. Rep. Prog. Chem., Sect. B: Org. Chem.

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This report surveys the 2009 literature on mechanisms of pericyclic reactions. Again, mechanistic studies of cycloadditions dominate, especially those of relevance to organic synthesis. Several electrocyclizations used in the synthesis of complex polycycles were also examined in detail, as were a number of sigmatropic shifts involving aza-polyenes. General theories and theoretical toolsGouverneur and co-workers provided a thorough review of pericyclic reactions involving fluoroorganic compounds, highlighting the synthetic utility of these reactions and both experimental and theoretical studies on their mechanisms with a focus on the effect of fluorine on their regio-and stereoselectivities. 1 Mandado and Ponec described the application of their multicenter bond indices to pericyclic reactions, 2 focusing in this report on electrocyclizations. The authors suggested that computed multicenter bond indices correlate with allowedness of pericyclic reactions and are likely to be applicable to other classes of pericyclic reactions. Cycloaddition reactions [4+2] ReactionsSantos and co-workers used quantum chemical calculations (MP2 and B3LYP) and NMR experiments to reexamine the mechanism of AlR 3 -promoted Diels-Alder reactions that employ dienophiles bearing the Evans chiral auxiliary (e.g., Scheme 1). 3 The authors concluded that models for the origins of stereoselectivity involving species in which Al bridges between the two carbonyl oxygens do not necessarily correspond to what actually occurs. Instead, the authors argued for the involvement of species in which Al is not chelated.

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Computational Investigation of Rearrangements in Huisgen Cycloadducts of Azolium N-Dicyanomethanide 1,3-Dipoles with Alkynes: A Mechanistic Panoply

Cited by 5 publications

References 79 publications

Competitive Pseudopericyclic [3,3]- and [3,5]-Sigmatropic Rearrangements of Trichloroacetimidates

Competitive Pseudopericyclic [3,3]- and [3,5]-Sigmatropic Rearrangements of Trichloroacetimidates

Theory, Experiment and Unusual Features of Potential Energy Surfaces of Pericyclic and Pseudopericyclic Reactions with Sequential Transition Structures

Reaction mechanisms : Part (ii) Pericyclic reactions

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