Strategies and approaches for constructing 1-oxadecalins

Tang, Yu; Oppenheimer, Jossian; Song, Zhenlei; You, Lingfeng; Zhang, Xuejun; Hsung, Richard P.

doi:10.1016/j.tet.2006.08.054

Cited by 108 publications

(38 citation statements)

References 217 publications

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“…The resultant benzoisoxazoline, 4 , could well be converted to benzopyran intermediate 7 through a sequence involving reductive N-O bond cleavage, followed by 1,4-elimination and, finally, 6π-electrocyclization. xxvii Finally, alkylative dearomatization of 7 would deliver intermediate 8 en route to cortistatin A. xxviii …”

Section: Introductionmentioning

confidence: 99%

Synthetic studies toward (+)-cortistatin A

2011

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We describe herein the synthesis of a late-stage intermediate en route to cortistatin A. Key transformations included a Snieckus-like cascade sequence culminating in a 6π-electrocyclization, an alkylative dearomatization, and the stereoselective functionalization of the cortistatin A-ring. While the total synthesis we sought was not accomplished, the work sets the stage for several approaches to the preparation of novel analogs via diverted total synthesis.

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Section: Introductionmentioning

confidence: 99%

Synthetic studies toward (+)-cortistatin A

2011

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“…In addition, diverse enamine methods have been developed that utilize enones and enals in combination with acid catalysts for the construction of six-membered ring heterocyclic 7,15 and carbocyclic 13d,16 compounds. Reactants other than enamines that include acrylic acid chlorides and esters 17 as well as allenes 18 and phosphorus ylides 19 and dipolar species that include aziridines 15a,20 and cyclopropanes 21 have been employed.…”

Section: Organocatalysismentioning

confidence: 99%

The [3 + 3]-Cycloaddition Alternative for Heterocycle Syntheses: Catalytically Generated Metalloenolcarbenes as Dipolar Adducts

2014

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ConspectusThe combination of two or more unsaturated structural units to form cyclic organic compounds is commonly referred to as cycloaddition, and the combination of two unsaturated structural units that forms a six-membered ring is formally either a [5 + 1]-, [4 + 2]-, [2 + 2 + 2]-, or [3 + 3]-cycloaddition. Occurring as concerted or stepwise processes, cycloaddition reactions are among the most useful synthetic constructions in organic chemistry. Of these transformations, the concerted [4 + 2]-cycloaddition, the Diels–Alder reaction, is by far the best known and most widely applied. However, although symmetry disallowed as a concerted process and lacking certifiable examples until recently, stepwise [3 + 3]-cycloadditions offer advantages for the synthesis of a substantial variety of heterocyclic compounds, and they are receiving considerable attention.In this Account, we present the development of stepwise [3 + 3]-cycloaddition reactions from virtual invisibility in the 1990s to a rapidly growing synthetic methodology today, involving organocatalysis or transition metal catalysis. With origins in organometallic or vinyliminium ion chemistry, this area has blossomed into a viable synthetic transformation for the construction of six-membered heterocyclic compounds containing one or more heteroatoms. The development of [3 + 3]-cycloaddition transformations has been achieved through identification of suitable and compatible reactive dipolar adducts and stable dipoles. The reactive dipolar species is an energetic dipolar intermediate that is optimally formed catalytically in the reaction. The stepwise process occurs with the reactive dipolar adduct reacting as an electrophile or as a nucleophile to form the first covalent bond, and this association provides entropic assistance for the construction of the second covalent bond and the overall formal [3 + 3]-cycloaddition. Organocatalysis is well developed for both inter- and intramolecular synthetic transformations, but the potential of transition metal catalysis for [3 + 3]-cycloaddition has only recently emerged. The key to the rapid development of the transition metal-based methodology has been recognition that certain catalytically generated vinylcarbenes are effective dipolar adducts for reactions with stable dipolar compounds, including aryl and vinyl ylides. In particular, metallo-enolcarbenes that are generated catalytically from conveniently prepared stable enoldiazoacetates or from donor–acceptor cyclopropenes are highly effective dipolar adducts for [3 + 3]-cycloaddition. The electron-donating oxygen of the silyl ether enhances electrophilic ring closure to the metal-bound carbon of the initial adduct from vinylogous addition, and this enhancement inhibits the alternative [3 + 2]-cycloaddition across the carbon–carbon double bond of the vinylcarbene.Catalytically generated metallo-enolcarbenes react under mild conditions with a broad spectrum of compatible stable dipoles, including nitrones, azomethine imines, ylides, and certain covalent precursors of s...

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“…Chromene and pyran cores are broadly found in natural products and pharmaceuticals [18,19] with a wide range of biological activities, such as antimicrobial, antifungal, antiproliferative, antisterility, and anticancer [20][21][22]. Also, they are vastly used in cosmetics, pigments, and agrochemicals [23,24].…”

Section: Introductionmentioning

confidence: 99%

Pyridylmethylaminoacetic acid functionalized Fe3O4 magnetic nanorods as an efficient catalyst for the synthesis of 2-aminochromene and 2-aminopyran derivatives

2017

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Abstract. 2-[(2-PyridylMethyl)Amino]Acetic acid (PMAA) functionalized Fe 3 O 4 superparamagnetic nanorods e ciently catalyzed three-component reaction of malononitrile, aromatic aldehydes, and phenolic or enolic components, such as -naphthol, -naphthol, dimedone, or kojic acid, to synthesize a variety of chromene or pyran derivatives in good to high yields. PMAA functionalized Fe3O4 magnetic nanorods were prepared via simple coprecipitation in an aqueous solution of Fe 2+ and Fe 3+ ions using NH 4 OH in the presence of glycine, followed by subjecting it to 2-pyridine carbaldehyde and then, NaBH 4 -mediated reduction of in-situ generated imine. Obtained nanorods were characterized by FT-IR, XRD, TGA, SEM, EDX, TEM, BET, and VSM analysis.

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Strategies and approaches for constructing 1-oxadecalins

Cited by 108 publications

References 217 publications

Synthetic studies toward (+)-cortistatin A

Synthetic studies toward (+)-cortistatin A

The [3 + 3]-Cycloaddition Alternative for Heterocycle Syntheses: Catalytically Generated Metalloenolcarbenes as Dipolar Adducts

Pyridylmethylaminoacetic acid functionalized Fe3O4 magnetic nanorods as an efficient catalyst for the synthesis of 2-aminochromene and 2-aminopyran derivatives

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