Exo-Selective Diels−Alder Reactions of Vinylazepines. Origin of Divergent Stereoselectivity in Diels−Alder Reactions of Vinylazepines, Vinylpiperideines, and Vinylcycloalkenes

Boren, Brant C.; Hirschi, Jennifer S.; Reibenspies, Joseph H.; Tallant, Matthew D.; Singleton, Daniel A.; Sulikowski, Gary A.

doi:10.1021/jo034462h

Cited by 22 publications

(19 citation statements)

References 33 publications

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“…The axial structure is slightly favored in keeping with related trends in other additions to cyclohexenes. 28 Each of the transition structures 7 , 8-ax , 8-eq , 9 , and 10 are spin-stable. )…”

Section: Resultsmentioning

confidence: 99%

Control Elements in Dynamically Determined Selectivity on a Bifurcating Surface

et al. 2008

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The mechanism and the nature of the dynamically-determined product selectivity in Diels-Alder cycloadditions of 3-methoxycarbonylcyclopentadienone (2) with 1,3-dienes was studied by a combination of product studies, experimental kinetic isotope effects, standard theoretical calculations, and quasiclassical trajectory calculations. The low-energy transition structures in these reactions are structurally balanced between [4π diene + 2π dienone ] and the [2π diene + 4π dienone ] modes of cycloaddition. The accuracy of these structures and their bispericyclic nature is supported by the experimental isotope effects. Trajectories passing through these transition structures can lead to both [4π diene + 2π dienone ] and [2π diene + 4π dienone ] cycloadducts, and the mixture of products obtained varies with the structure of the diene. The factors affecting this selectivity are analyzed. The geometry of the transition structure is a useful predictor of the major product, but the selectivity is also guided by the shape of the energy surface as trajectories approach the products and by how trajectories cross the transition state ridge.

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Section: Resultsmentioning

confidence: 99%

Control Elements in Dynamically Determined Selectivity on a Bifurcating Surface

et al. 2008

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“…Apart from some isolated cases,4, 5 certain structural motifs on the dienophile are well-known to lead predominantly to exo cycloadducts, including conformationally restricted cyclic s- cis- dienophiles,6 and α-halo α,β-unsaturated carbonyl compounds 7…”

Section: Introductionmentioning

confidence: 99%

Diels−Alder Exo Selectivity in Terminal-Substituted Dienes and Dienophiles: Experimental Discoveries and Computational Explanations

et al. 2009

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The Diels-Alder reactions of a series of silyloxydienes and silylated dienes with acyclic α,β-unsaturated ketones and N-acyloxazolidinones have been investigated. The endo/exo stereochemical outcome is strongly influenced by the substitution pattern of the reactants. High exo selectivity was observed when the termini of the diene and the dienophile involved in the shorter forming bond are both substituted, while the normal endo preference was found otherwise. The exo-selective asymmetric Diels-Alder reactions using Evans' oxazolidinone chiral auxiliary furnished a high level of π-facial selectivity in the same sense as their well-documented endo-selective counterparts. Computational results of these Diels-Alder reactions were consistent with the experimental endo/ exo selectivity in most cases. A twist-asynchronous model accounts for the geometries and energies of the computed transition structures.

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“…For example, they may be used as dienes in hexannelations en route to the synthesis of polycylic alkaloids such as stenine (see Figure 1). 13 Historically, palladium-catalyzed alkenylation of enamides related to 1a/b is possible at C-2 under Heck-type conditions and at C-3 under the Fujiwara–Moritani 14 conditions. 3 As such, a mixture containing 1a , styrene ( 3a ), 5 mol % of Pd(OAc) 2 , and 1 equiv of Cu(OAc) 2 , 3,15 in DMF was warmed to 80 °C.…”

Section: α-Alkenylation Of 1a/bmentioning

confidence: 99%

“…Previously, Occhiato, Coudert, and Sulikowski have reported isolated examples of cross-couplings of vinyl triflate ( I , Figure 2, top), 7 vinyl phosphate ( II ), 9 and α-iodo enecarbarmate ( III ), 13 respectively, with metalated coupling partners. 7 The instability of I , II , and III , as noted by the authors, 7,13 likely necessitated the use of highly reactive metalated cross-coupling partners. The lability of the substrates under the coupling conditions, and especially of the enecarbamate-derived products (due to their proneness to ring-opening 7 ), diminishes the practicality of these previously reported methodologies.…”

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confidence: 99%