Memory Effects in Palladium‐Catalyzed Allylic Alkylations of 2‐Cyclohexen‐1‐yl Acetate

Svensen, Nina; Fristrup, Peter; Tanner, David; Norrby, Per‐Ola

doi:10.1002/adsc.200700315

Cited by 25 publications

(16 citation statements)

References 37 publications

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“…This procedure maintains the overall charge, minimizing computational artifacts arising from imperfect solvation of complexes with different charges. 12 All calculations were performed in Jaguar 25 with B3LYP-D3, which uses the dispersion-correction of Grimme and co-workers 26 together with the classical B3LYP functional. 27 We utilized the LACVP* basis set 28 and PBF solvation 29 with default parameters for THF.…”

Section: Resultsmentioning

confidence: 99%

“…Aer observing a switch in regioselectivity upon changing the size of substituent at the 2-position, we employed the larger 2-cyclohexyl group to further explore this trend. Substrate 1j underwent reaction with NaCH(CO 2 Me) 2 and catalyst generated from [Pd(allyl)Cl] 2 or Pd(OAc) 2 to afford predominantly product 2j via benzylic attack with regioselectivities of 84 : 16 and 86 : 14, respectively (entries [11][12][13]. It is noteworthy that benzylic acetate 1j is more reactive with the Pd(OAc) 2 -based catalyst than aliphatic acetate 1h, which did not react with this catalyst (as noted earlier).…”

Section: Factors Controlling Regioselectivity With 2-alkyl Substitute...mentioning

confidence: 99%

“…However, if the isomerization is slow relative to nucleophilic attack, 10 or in the presence of chiral 11 or electronically differentiated 12 ligands, the reaction can show strong memory effects. Under conditions of slow isomerization, nucleophilic attack has a strong preference for reaction at anti -oriented termini.…”

Section: Introductionmentioning

confidence: 99%

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Breaking conjugation: unusual regioselectivity with 2-substituted allylic substrates in the Tsuji–Trost reaction

et al. 2014

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η3-Allyl palladium complexes are key intermediates in Tsuji-Trost allylic substitution reactions. It is well known that (η3-1-aryl-3-alkyl substituted allyl)Pd intermediates result in nucleophilic attack at the alkyl substituted terminus. In contrast, the chemistry of (η3-1,2,3-trisubstituted allyl)Pd intermediates is relatively unexplored. Herein we probe the regioselectivity with 1,2,3-trisubstituted allylic substrates in Tsuji-Trost allylic substitution reactions. DFT investigation of cationic (η3-1-Ph-2-B(pin)-3-alkyl-allyl)Pd(PPh3)2 intermediates predict that nucleophilic attack should occur preferentially on anti-allyls rather than the syn-isomers to generate benzylic substitution products under Curtin-Hammett conditions. Experimentally, systematic studies with 1,2,3-trisubstituted allylic substrates revealed that a Linear Free Energy Relationship (LFER) is observed when Charton steric parameters of the C-2 substituents are plotted against the log of the ratio of regioisomers. Bulkier C-2 substituents in 1,2,3-trisubstituted η3-allyl palladium intermediates provide stronger preference for nucleophilic attack at anti-oriented benzylic termini. Additionally, the geometry of 1,4-elimination products supports the presence of anti-allyl palladium intermediates.

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Section: Resultsmentioning

confidence: 99%

Section: Factors Controlling Regioselectivity With 2-alkyl Substitute...mentioning

confidence: 99%

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Breaking conjugation: unusual regioselectivity with 2-substituted allylic substrates in the Tsuji–Trost reaction

et al. 2014

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“…The mechanism of the reaction may vary according to the conditions used, but the general steps are the complexation of the olefin to palladium, followed by oxidative addition, nucleophilic attack on the p-allyl and dissociation of the product (Scheme 2) [15].…”

Section: Introductionmentioning

confidence: 99%

Palladium-Catalyzed Enantioselective Allylic Substitution

Milhau

Guiry

2011

Topics in Organometallic Chemistry

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Palladium-catalyzed allylic substitution is one of the main reactions for testing new chiral ligands. The most relevant examples from the work published in the period 2007 to mid-2010 are reviewed. The vast majority of the work published within this timeframe relies upon the application of chiral ligands for asymmetric induction. The recent advances in the development and applications of new chiral P-P, P-N, P-O, P-S, N-N, N-S, S-S, and NHC ligands are covered and are the main focus of this chapter. Other aspects of enantioselective palladium allylic alkylations are discussed in the subsequent sections, for example, heterogeneous catalysis, the use of chiral salt additives, and recent applications in kinetic resolution.

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“…[44] Analogously, in nucleophilic additions to monosubstituted (h 3 -allyl)Pd complexes, it has been assumed that (due to the relative trans influences of the ligands) [45] the nucleophile would preferentially attack the allylpalladium terminus trans to the phosphine ligand. [46] The plausible transition structures involving both the allylic carbons and both the d-and e-OH functionalities have been calculated starting from the [Pd(h 3 -allyl)] complexes 31 and 31' (Figure 4). The optimized transition structures show an Hbonding interaction between the attacking nucleophile and the iodide.…”

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A Versatile Synthesis of β‐Lactam‐Fused Oxacycles through the Palladium‐Catalyzed Chemo‐, Regio‐, and Diastereoselective Cyclization of Allenic Diols

Alcaide

Almendros

Carrascosa

et al. 2014

Chemistry A European J

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Chemo-, regio- and stereocontrolled palladium-catalyzed preparations of enantiopure morpholines, oxocines, and dioxonines have been developed starting from 2-azetidinone-tethered γ,δ-, δ,ε-, and ε,ζ-allendiols. The palladium-catalyzed cyclizative coupling reaction of γ,δ-allendiols 2 with allyl bromide or lithium bromide was effective as 8-endo cyclization by attack of the primary hydroxy group to the terminal allene carbon to afford enantiopure functionalized oxocines; whereas the palladium-catalyzed cyclizative coupling reaction of 2-azetidinone-tethered ε,ζ-allendiols 4 furnished dioxonines 16 through a totally chemo- and regioselective 9-endo oxycyclization. By contrast, the palladium-catalyzed cyclizative coupling reaction of 2-azetidinone-tethered δ,ε-allendiols 3 with aryl and alkenyl halides exclusively generated six-membered-ring compounds 14 a and 15 a. These results could be explained through a 6-exo cyclization by chemo- and regiospecific attack of the secondary hydroxy group to the internal allene carbon. Chemo- and regiocontrol issues are mainly influenced by the length of the tether rather than by the nature of the metal catalysts and substituents. This reactivity can be rationalized by means of density functional theory calculations.

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Memory Effects in Palladium‐Catalyzed Allylic Alkylations of 2‐Cyclohexen‐1‐yl Acetate

Cited by 25 publications

References 37 publications

Breaking conjugation: unusual regioselectivity with 2-substituted allylic substrates in the Tsuji–Trost reaction

Breaking conjugation: unusual regioselectivity with 2-substituted allylic substrates in the Tsuji–Trost reaction

Palladium-Catalyzed Enantioselective Allylic Substitution

A Versatile Synthesis of β‐Lactam‐Fused Oxacycles through the Palladium‐Catalyzed Chemo‐, Regio‐, and Diastereoselective Cyclization of Allenic Diols

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