Carbopalladation of allenic hydrocarbons.

Ahmar, Mohammed; Barieux, J.-J.; Cazes, Bernard; Goré, J.

doi:10.1016/s0040-4020(01)89984-1

Cited by 73 publications

(11 citation statements)

References 44 publications

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“…The Robinson annelation represents an early milestone.151 The culmination of steroid synthesis by polyolefin cyclization some fifty years later systematizes cation-induced cyclizations as a good strategy for ring formation if the proper initiator and terminator are found. [61 The discovery and structure elucidation of prostaglandins in the 1960s unleashed a fierce attack on methods for fivemembered ring synthesis. 17.…”

Section: Introductionmentioning

confidence: 99%

Cyclizations via Palladium‐Catalyzed Allylic Alkylations [New Synthetic Methods (79)]

Trost

1989

Angew. Chem. Int. Ed. Engl.

300

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The history of ring systems in organic chemistry parallels their synthetic accessibility. Transition-metal-catalyzed cyclizations offer a new opportunity to create carbo-and heterocyclic compounds with great facility. Among these methods, allylic alkylations catalyzed by palladium have proven unusually productive because of the extraordinary chemo-, regio-, and diastereoselectivity and the continuing possibility for the development of enantioselectivity. The rules for ring closure differ from those for non-transition-metal-catalyzed reactions. A major benefit is the ability to generate medium (eight-, nine-, ten-, and eleven-membered) and large rings in preference to normal (five-, six-and seven-membered) rings. With the appropriate substrate, efficient macrocyclizations are possible under conditions of normal concentrations. A second major benefit derives from the complementary stereochemistry of the metalcatalyzed substitution (net retention of configuration) compared to non-metal-catalyzed reactions (inversion of configuration). Further, the requirement for the substrate to conform to the transition-metal template may impose a stereochemical preference in the intermediate that ultimately translates into the thermodynamically less stable organic product regardless of the stereochemistry of the starting material. While more work has focused on carbocyclic synthesis, the possibilities for heterocyclic synthesis are just beginning to be tapped. In addition to forming heterocycles by C-C bond formation, use of a heteroatom as a nucleophile has already proven effective for oxygen and nitrogen, with other nucleophiles awaiting investigation. New dimensions for cyclization via allylic alkylation arise by generating the requisite 7r-allylpalladium intermediates by methods other than palladium(0)-initiated allylic ionizations. In addition, metals other than palladium will clearly expand the possibilities, but as yet remain untapped.

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Section: Introductionmentioning

confidence: 99%

Cyclizations via Palladium‐Catalyzed Allylic Alkylations [New Synthetic Methods (79)]

Trost

1989

Angew. Chem. Int. Ed. Engl.

300

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“…Thus, the C-5 carbon nucleus of cyclopentenone (E)-4 resonates at high-field (δ = 37-39 ppm) compared to the analogous carbon of the (Z)-4 isomer (δ = 40-43 ppm) because of the shielding due to a positive cis-γ-effect (γ-compression effect) from the allylic carbon (C-4)=C-CH 2 at δ = 30-31 ppm [δ = 37.3 ppm for (E)-4cb and 42.8 ppm for (Z)-4cb]. [45,46] A similar shielding effect is observed for the C-3 carbon in cyclopentenone (Z)-4, which resonates at higher field [δ =167.7 ppm for (Z)-4cb], whereas it is further downfield for the isomer (E)-4 [δ =168.2 ppm for (E)-4cb]. This last shielding effect is stronger (by approximately 5 ppm) for the C-3 carbon of 3-unsubstituted cyclopentenones (Z)-4 (RЈ = H).…”

Section: Structure and Stereochemistry Assignments Of 4-and 5-alkylidmentioning

confidence: 99%

Pauson–Khand Reaction of Allenic Hydrocarbons: Synthesis of 4‐Alkylidenecyclopentenones

et al. 2010

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“…The reaction takes place in boiling MeCN in the presence of 5 mol % [Pd(PPh 3 ) 4 ] and 10 mol % nBu 4 NBr, with a variety of organic halides, including phenyl bromide, as well as phenyl triflate participating as coupling partners. On some rare occasions, however, the premature three-membered cycle 82, normally obtained in the absence of imine, [47,48] is isolated as side product. Scheme 30 …”

Section: Carbopalladation Of Allenesmentioning

confidence: 99%

Pd‐Assisted Multicomponent Synthesis of Heterocycles

2003

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This review highlights some remarkable recently made achievements in the application of palladium‐mediated processes to the design of multicomponent one‐pot syntheses of heterocyclic compounds. Palladium‐catalysed cascade reactions are surveyed, together with processes based on sequential, one‐pot performance of individual transformations in which at least one is catalysed by palladium. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)

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Carbopalladation of allenic hydrocarbons.

Cited by 73 publications

References 44 publications

Cyclizations via Palladium‐Catalyzed Allylic Alkylations [New Synthetic Methods (79)]

Cyclizations via Palladium‐Catalyzed Allylic Alkylations [New Synthetic Methods (79)]

Pauson–Khand Reaction of Allenic Hydrocarbons: Synthesis of 4‐Alkylidenecyclopentenones

Pd‐Assisted Multicomponent Synthesis of Heterocycles

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