Palladium-Catalyzed Carbonylation of <i>o</i>-Iodophenols with Allenes

Okuro, Kazumi; Alper, Howard

doi:10.1021/jo962283c

Cited by 78 publications

(27 citation statements)

References 22 publications

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“…Several methods have been published describing activation of allenes towards coupling with oxygen nucleophiles (including N-bromosuccinimide, HgCl 2 ), 11 but these routes are not attractive in view of the stoichiometric use of the reagents. At this point, a publication of Alper and coworkers appeared, 12 who obtained a similar acetal as a byproduct in Pd(II)-catalyzed annulation reactions with substituted allenes. Application of their conditions and further optimization (Pd(OAc) 2 (cat.…”

Section: Methodsmentioning

confidence: 99%

A Novel Transition Metal-Catalyzed Route to Functionalized Dihydropyrans and Tetrahydrooxepines

Rutjes

Kooistra

Hiemstra

et al. 1998

Synlett

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A straightforward route for the synthesis of α,α'-disubstituted dihydropyrans and tetrahydrooxepines has been developed involving Pd-and Ru-catalyzed reactions.2,6-Disubstituted dihydropyrans 1 and 2 (n = 1) occur frequently in nature as a structural unit in a wide range of natural products. 1 In addition, these compounds could serve as useful building blocks for the synthesis of biologically active saturated oxygen heterocycles via functionalization of the double bond. Examples include (poly)cyclic ethers, 2 but also modified carbohydrates and 2-carboxyl-substituted tetrahydropyrans with antibacterial activity such as KDO. 3 More specifically, dihydropyrans 2 (R 1 = OMe) have recently been used as intermediates in the synthesis of mevinolin and compactin. 4,5 In conjunction with previous work in our group on vinylsilane-terminated formation of dihydropyrans via oxycarbenium ions, 6 we set out to explore a novel entry into this compound class, which would enable us to vary the side chains and would also give facile access to enantiopure heterocycles. Moreover, the methodology outlined in this paper is not restricted to six-membered ring formation, but can also be applied to form the corresponding seven-membered rings. Especially the latter aspect provides a significant benefit compared to previously established methods for forming such rings via hetero Diels-Alder reactions. 5,7 A short retrosynthetic outline of our route is shown in Scheme 1. Scheme 1The target compounds 1 and 2 should be accessible via the allylic acetal 3, which contains (i) a terminal olefin function that can be used as a handle for ring-closing metathesis 8,9 and (ii) an acetal function to enable later modification of the system via oxycarbenium ion chemistry.The first sequence (Scheme 2) commenced with anhydrous methyl glyoxylate (5), 10 which upon treatment with BF 3 ·OEt 2 and allyltrimethylsilane led to methyl 2-hydroxy-4-pentenoate (6). Initially, attempts were made to convert 6 into the desired allylic acetal under acid-catalyzed conditions with acrolein derivatives, but without much success. Therefore, we turned our attention to other strategies, involving the use of 1-methoxy-1,2-propadiene, 11 which upon electrophilic activation and subsequent reaction with the secondary alcohol might give rise to the desired product. Several methods have been published describing activation of allenes towards coupling with oxygen nucleophiles (including N-bromosuccinimide, HgCl 2 ), 11 but these routes are not attractive in view of the stoichiometric use of the reagents. At this point, a publication of Alper and coworkers appeared, 12 who obtained a similar acetal as a byproduct in Pd(II)-catalyzed annulation reactions with substituted allenes. Application of their conditions and further optimization (Pd(OAc) 2 (cat.), Ph 2 P(CH 2 ) 3 PPh 2 (dppp), excess of 1-methoxy-1,2-propadiene, Et 3 N, MeCN, 80 °C in a sealed tube) led to a virtually quantitative yield of the desired acetal 7. 13 Not surprisingly, 7 was obtained as a ca. 1:1 mixture of diaste...

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Section: Methodsmentioning

confidence: 99%

A Novel Transition Metal-Catalyzed Route to Functionalized Dihydropyrans and Tetrahydrooxepines

Rutjes

Kooistra

Hiemstra

et al. 1998

Synlett

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“…Quinolin-4(1 H )-ones 177 were obtained by a Pd(0)-catalysed termolecular queuing process involving oxidative addition to aryl iodide 176 , followed by carbonylation, allene insertion and capture of the resulting п-allyl-Pd(II) species by an internal N -nucleophile [79]. CO at atmospheric pressure was used in contrast to Alper′s similar reported cascades [80], which were performed at high pressures of CO (20 atm). Under optimal conditions, using allene (1 atm) and CO (1 atm), a (3 + 1 + 2)-cycloaddition reaction of 2-iodo-1-tosylaniline occurred giving quinolin-4(1 H )-ones 177 in good yields (55–99%) (Scheme 58).…”

Section: Synthesis Of Quinolin-4(1h)-onesmentioning

confidence: 99%

Palladium-Catalysed Synthesis and Transformation of Quinolones

Silva

2019

Molecules

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Palladium-catalysed reactions have had a large impact on synthetic organic chemistry and have found many applications in target-oriented synthesis. Their widespread use in organic synthesis is due to the mild conditions associated with the reactions together with their tolerance of a wide range of functional groups. Moreover, these types of reactions allow the rapid construction of complex molecules through multiple bond-forming reactions in a single step, the so-called tandem processes. Pd-catalysed reactions have been applied to the synthesis of a large number of natural products and bioactive compounds, some of them of complex molecular structures. This review article aims to present an overview of the most important Pd-catalysed reactions employed in the synthesis and transformations of quinolin-2(1H)-ones and quinolin-4(1H)-ones. These compounds are widely recognized by their diverse bioactivity, being privileged structures in medicinal chemistry and useful structural moieties for the development of new drug candidates. Furthermore, they hold significant interest due to their host–guest chemistry; applications in chemical, biochemical and environmental analyses and use in the development of new synthetic methods. In some cases, the quinolone formation step cannot be ascribed to a claimed Pd-catalysed reaction but this reaction is crucial to get the appropriate substrate for cyclization into the quinolone. Herein we present and discuss different economical, efficient and selective synthetic strategies to access quinolone-type compounds.

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“…These structures may have been reported with antibacterial or antitumor activities (Scheme 8). Alper and coworkers reported the first carbonylation reaction with 2-iodophenols and allenes [31]. Using 5 mol% of Pd(OAc) 2 /dppb as the catalyst and i Pr 2 NEt as the base, the reaction favored isomer A in high regioselectivity, especially when terminal allenes (R 1 ¼H) were employed.…”

Section: Chromone and Flavonoid Derivativesmentioning

confidence: 99%

Palladium-Catalyzed Carbonylative Synthesis of Six-Membered Heterocycles from Aryl Halides

2015

Topics in Heterocyclic Chemistry

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Palladium-Catalyzed Carbonylation of o-Iodophenols with Allenes

Cited by 78 publications

References 22 publications

A Novel Transition Metal-Catalyzed Route to Functionalized Dihydropyrans and Tetrahydrooxepines

A Novel Transition Metal-Catalyzed Route to Functionalized Dihydropyrans and Tetrahydrooxepines

Palladium-Catalysed Synthesis and Transformation of Quinolones

Palladium-Catalyzed Carbonylative Synthesis of Six-Membered Heterocycles from Aryl Halides

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