Palladium-catalyzed cross-coupling of unsaturated phenols with vinylic halides and triflates

Larock, Richard C.; Yang, Hoseok; Pace, Paola; Cacchi, Sandro; Fabrizi, Giancarlo

doi:10.1016/s0040-4039(97)10502-0

Cited by 21 publications

(5 citation statements)

References 11 publications

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“…Stronger, anionic nucleophiles appear to favor the cyclization path. 2 Therefore, the reaction of ethyl 2-allyl-3-oxobutanoate with 17β-acetoxyandrosta-3,5dienyl-3-yl triflate (Scheme 3), our model system, was initially investigated in the presence of a variety of bases. The presence of additives has also been found to play a key role.…”

Section: Methodsmentioning

confidence: 99%

“…The preparation of heterocyclic compounds based on the intramolecular nucleophilic attack on η 3 -allylpalladium complexes derived from olefins containing proximate nucleophiles and vinylic triflates or halides is evolving as an efficient and versatile synthetic methodology (Scheme 1). A variety of oxygen 1 and nitrogen 2,3 heterocycles have been obtained according to this protocol.…”

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confidence: 99%

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Synthesis of Dihydropyrans via Pd-Catalyzed Cyclization of 2-Allyl-1,3-dicarbonyl Compounds and Vinylic Triflates or Halides

Cacchi¹,

Fabrizi²,

Larock³

et al. 1998

Synlett

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The palladium-catalyzed reaction of 2-allyl-1,3-dicarbonyl compounds with vinylic triflates or halides affords dihydropyran derivatives, most probably through the intermediacy of η 3 -allylpalladium complexes that undergo an intramolecular nucleophilic attack by the oxygen.The preparation of heterocyclic compounds based on the intramolecular nucleophilic attack on η 3 -allylpalladium complexes derived from olefins containing proximate nucleophiles and vinylic triflates or halides is evolving as an efficient and versatile synthetic methodology (Scheme 1). A variety of oxygen 1 and nitrogen 2,3 heterocycles have been obtained according to this protocol. Scheme 1As a further extension of this chemistry, we now report our preliminary results on the utilization of readily available 2-allyl-1,3-dicarbonyl compounds 1 4 as convenient building blocks for the preparation of the substituted dihydropyrans 3 (Scheme 2). Scheme 2Prior experience has shown that the nature of the nucleophile in these reactions can be of considerable importance in controlling the ratio of cyclization to vinylic substitution (see Scheme 4). Stronger, anionic nucleophiles appear to favor the cyclization path. 2 Therefore, the reaction of ethyl 2-allyl-3-oxobutanoate with 17β-acetoxyandrosta-3,5-dienyl-3-yl triflate (Scheme 3), our model system, was initially investigated in the presence of a variety of bases. The presence of additives has also been found to play a key role. Some of our results are summarized in Table 1.

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Section: Methodsmentioning

confidence: 99%

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confidence: 99%

Synthesis of Dihydropyrans via Pd-Catalyzed Cyclization of 2-Allyl-1,3-dicarbonyl Compounds and Vinylic Triflates or Halides

Cacchi¹,

Fabrizi²,

Larock³

et al. 1998

Synlett

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“…CH2Cl2 was the optimal one, producing 2a in 75% yield (entry 7). Other solvents including THF, toluene, EtOAc, and MeCN afforded 2a in moderate yields (entries [8][9][10][11][12]. Only trace amount of 2a was observed in N,N-dimethylformamide (DMF) (entry 13).…”

Section: Synlettmentioning

confidence: 99%

“…Under the optimized reaction conditions, the substrate scope of the intramolecular allylic reaction was investigated (Scheme 2). 12 A wide variety of secondary allylic alcohols 1 containing either electron-withdrawing or electron-donating substituents on the phenyl rings were all suitable substrates. The substituents on the phenyl ring could be halide (2b, 2d, 2h-2k), alkyl (2c, 2e, 2f), and alkoxyl (2g), providing the corresponding 2-vinyl chromans 2a-2k in 57-84% yields.…”

Section: Synlettmentioning

confidence: 99%

Brønsted Acid Catalyzed Intramolecular Allylic Substitution Reaction of Allylic Alcohols: A Facile Synthesis of 2-Vinylchromans

Ding,

Xu,

et al. 2024

Synlett

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Brønsted acid-catalyzed intramolecular allylic substitution reaction of secondary and tertiary allylic alcohols has been developed. A variety of 2-vinylchromans were efficiently prepared in moderate to excellent yields. The given method features wide substrate scope, operational simplicity, metal-free, and mild reaction conditions. The practicability of the method was demonstrated by the gram-scale reaction and further derivations of the product. Catalytic asymmetric reaction was preliminarily studied.

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“…and Pd[214][215][216][217][218][219] catalyzed reaction conditions for transformations to similar 5-membered heterocyclic substructures through phenols or acetate protected substrates. A variation to this strategy should provide the desired products in good yield with minimal steps.…”

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New synthesis and reactions of phosphonates

Richardson¹

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The importance of phosphorus can be highlighted not only through its biological significance, but also in its many varied industrial, medicinal, and synthetic applications.Phosphonate moieties in particular have broad applications including their use as reagents in the Horner-Wadsworth-Emmons olefination reaction, a widely used synthetic strategy.As an alternative to the often harsh conditions required for phosphonate synthesis, a mild and versatile one-flask protocol has been developed in which a benzylic alcohol can be directly converted to the diethyl benzylphosphonate ester. Moreover, this zinc iodide mediated process provides good yields on both small and larger scale reactions.Explorations into this unique transformation with non-racemic substrates revealed that the reaction may proceed through an S N 1-like mechanism.The new phosphonate methodology has been utilized successfully on allylic, heterocyclic, and both electron poor and rich benzylic systems. This allows the synthesis of many types of dialkyl benzylphosphonate esters. Specific examples include compounds used towards the synthesis of natural product analogues and at least one phosphonate ester not previously attainable under standard conditions. Isotopic labelling experiments provided additional mechanistic insight suggesting a probable carbocation process. The mild and facile reaction conditions and the good yields of diverse, complex phosphonate products emphasize the broad applicability of this protocol.To demonstrate the utility of this phosphorus-based methodology, synthetic sequences and Lewis acid-mediated cascade cyclizations towards the synthesis of natural products have been developed. The natural radulanins, isolated from liverworts, possess a plethora of biological properties and present the opportunity to utilize and expand upon many aspects of this research. Formation of the benzoxepin core of the radulanins through a Lewis acid-mediated cyclization ultimately led to the total synthesis of radulanin A. An additional product consisting of cyclization with electrophilic aromatic 2 substitution of a methoxymethyl substituent originating in the MOM-protecting group also was discovered, leading to a highly substituted benzoxepin that should be of value in the synthesis of radulanin E. Abstract Approved:Thesis Supervisor

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Palladium-catalyzed cross-coupling of unsaturated phenols with vinylic halides and triflates

Cited by 21 publications

References 11 publications

Synthesis of Dihydropyrans via Pd-Catalyzed Cyclization of 2-Allyl-1,3-dicarbonyl Compounds and Vinylic Triflates or Halides

Synthesis of Dihydropyrans via Pd-Catalyzed Cyclization of 2-Allyl-1,3-dicarbonyl Compounds and Vinylic Triflates or Halides

Brønsted Acid Catalyzed Intramolecular Allylic Substitution Reaction of Allylic Alcohols: A Facile Synthesis of 2-Vinylchromans

New synthesis and reactions of phosphonates

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