Heteroatom‐Nucleophile‐Induced CC Fragmentations: Synthesis of Allenes and Entry to Domino Reactions

Saget, Tanguy; Cramer, Nicolai

doi:10.1002/anie.201004795

Cited by 34 publications

(8 citation statements)

References 56 publications

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“…It is of note that the formation of 6 from 3 a , and ultimately, from 2‐methyl‐1,3‐cyclopentanedione highlights the ability of such cyclic 1,3‐diones to act as convenient synthons of a formal 1,4‐dicarbonyl dipole, as seen in Scheme B. A related concept was recently exploited by Saget and Cramer in the synthesis of functionalized allenes 19…”

Section: Resultsmentioning

confidence: 99%

Hypervalent Activation as a Key Step for Dehydrogenative ortho CC Coupling of Iodoarenes

Arenas

Broomfield

et al. 2015

Chemistry A European J

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Abstract:Building on earlier results, we report here a direct metalfree a-arylation of substituted cyclic 1,3-diones using ArI(O2CCF3)2 reagents; unlike other arylative approaches, the arylated products which retain the iodine substituent ortho to the newly formed C-C bond. The mechanism was explored using DFT calculation showing a vanishingly small activation barrier for the C-C bond-forming step. In fact, taking advantage of an efficient in situ hypervalent activation, the iodoarenes are shown to undergo a cross-dehydrogenative C-C coupling at the C-H ortho to the iodine. When using Oxone® as terminal oxidant, the process was found to benefit from a rapid initial formation of the hypervalent ArI(OR)2 species and the sulphateaccelerated final coupling with a ketone. The method complements the ipso-selectivity obtained in the metal-catalysed α-arylation of carbonyl compounds..

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Section: Resultsmentioning

confidence: 99%

Hypervalent Activation as a Key Step for Dehydrogenative ortho CC Coupling of Iodoarenes

Arenas

Broomfield

et al. 2015

Chemistry A European J

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“…We have been developing ring-opening fragmentation reactions that produce diverse keto-alkyne building blocks (Scheme ). , These triflate-centered studies build on the pioneering work of Eschenmoser, Coke, and others and perhaps foreshadow recent efforts to produce allenes . Our ongoing methodology is proving useful for synthesis .…”

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confidence: 99%

Synthesis of High-Value 1,6-Enynes by Tandem Fragmentation/Olefination

Hoang

Dudley

2013

Org. Lett.

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A tandem process provides high-value 1,6-enynes that are otherwise difficult to prepare. Two base-mediated reactions-fragmentation and olefination-are executed in a coordinated manner that is overall more efficient than either reaction on its own. The 1,6-enynes can be strategically employed in conjunction with carbocyclization to deliver important targets, as noted for reported syntheses of hirsutene and illudol.

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“…In 2010, Cramer and coworkers developed a heteroatominduced Grob-type fragmentation of vinyl triflates to form allenes containing a terminal carbonyl functionality; 154 one example is illustrated in Scheme 115a. Cramer applied this fragmentation method to 364 to form the hydroxamic acid 366 in good yield.…”

Section: Nitrogen-and Oxygen-centered Radicalsmentioning

confidence: 99%

Mechanistic Aspects and Synthetic Applications of Radical Additions to Allenes

2019

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More than 50 years have passed since Haszeldine reported the first addition of a trifluoromethyl radical to an allene; in the intervening years, both the chemistry of allenes and the reactivity of single-electron species have become topics of intense interest. In this Review, we provide an overview of the fundamentals of radical additions to allenes and highlight the emergence of theoretical and experimental evidence that reveals unique reactivity patterns for radical additions to allenes as compared with other unsaturated compounds. Factors capable of exerting control over the chemo-, regio-, and stereoselectivities of the attack of carbon-and heteroatom-based radicals at each of the three potential reactive sites in an allene substrate are described. These include reaction conditions, the nature of the attacking radical, the substitution pattern of the allene, and the length of the linker between the radical center and the proximal allene carbon in the substrate. Cycloaddition reactions between allenes and partners containing π-bonds, which are likely to proceed through radical pathways, are presented to highlight their ability to rapidly access complex polycyclic scaffolds. Finally, the synthetic utility of the products arising from these chemistries is described, including their applications to the construction of complex molecules.

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Heteroatom‐Nucleophile‐Induced CC Fragmentations: Synthesis of Allenes and Entry to Domino Reactions

Cited by 34 publications

References 56 publications

Hypervalent Activation as a Key Step for Dehydrogenative ortho CC Coupling of Iodoarenes

Hypervalent Activation as a Key Step for Dehydrogenative ortho CC Coupling of Iodoarenes

Synthesis of High-Value 1,6-Enynes by Tandem Fragmentation/Olefination

Mechanistic Aspects and Synthetic Applications of Radical Additions to Allenes

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