Synthetic applications of 2-phenylselenenylenones—III

Liotta, Dennis; Saindane, Manohar; Barnum, Christopher; Zima, George

doi:10.1016/s0040-4020(01)96727-4

Cited by 34 publications

(13 citation statements)

References 20 publications

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“…Completion of the synthesis of (±)-cylindricine C required an oxidation of 16 to the corresponding 2H-piperidonyl enone 17 in order to incorporate the n-hexyl side chain at C-2 by an eventual cuprate conjugate addition. A variety of standard oxidative methods such as IBX, 28 PhSeCl/oxidation, 29 Saegusa, 30 and α-halo elimination failed to produce any synthetically useful quantity of enone 17. However, mercuric acetate eventually emerged as a superior reagent for introducing unsaturation into the 4-piperidone ring.…”

Section: Synthetic Methodsmentioning

confidence: 99%

A conjugate addition-dipolar cycloaddition approach towards the synthesis of various alkaloids

Flick¹,

Padwa²

2010

Arkivoc

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Section: Synthetic Methodsmentioning

confidence: 99%

A conjugate addition-dipolar cycloaddition approach towards the synthesis of various alkaloids

Flick¹,

Padwa²

2010

Arkivoc

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“…β-43 seems a challenging substrate, considering its antirelationship between the selenoxide moiety and the adjacent C3 proton in the possible intermediate J. Pleasingly, however, by treatment with H 2 O 2 (NaHCO 3 , THF, H 2 O, r.t., 14 h), β-43 underwent slow, but steady olefination to give 44 in 85% yield. We assumed that the success was the result of a base-induced epimerization at C2; 36 due to the enhanced acidity of the C2 proton by the presence of both the iso-…”

Section: Syn Thesismentioning

confidence: 99%

Total Synthesis of Bis-anthraquinone Antibiotic BE-43472B

et al. 2018

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This is a full account of our synthetic endeavor on the total synthesis of bis-anthraquinone antibiotic BE-43472B, an unusual octacyclic aromatic polyketide with a bis-anthraquinone scaffold. Three key steps enabled a facile access to the anthraquinone unit corresponding to the ABCF rings; (1) cyclo-condensation or -addition of benzonitrile oxides with cyclic enone derivatives, (2) benzoin cyclization for the stereoselective ring fusion with an angular hydroxy group, and (3) pinacol rearrangement for stereoselective installation of the angular aryl group. Other keys for the success include, (4) diastereoselective methylation of a lactol derivative, and (5) late-stage installation of the C3 hydroxy group through stereoselective oxirane ring formation via halohydrin derivatives. Whereas oxidation of the double bond in the enone with an adjacent 1,3-diketone moiety failed, the projected oxidation was achieved with the alkene keeping the isoxazole moiety intact as a 1,3-diketone equivalent. In the racemic total synthesis, X-ray crystal structure analysis of the target was achieved, proving the three-dimensional architecture for the first time. The asymmetric total synthesis was also achieved by exploiting a cycloadduct of the nitrile oxide and the enantiomerically pure cyclohexenone, which was convertible to the common intermediate via dehydrogenation followed by alkoxycarbonylation.

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“…In principle, the corresponding -phenylseleno alkenones could also serve as effective dienophiles for Diels-Alder reaction [24], providing facile access to -phenylseleno ketones, which might be useful in the preparation of various , -unsaturated cyclic ketones or have potential to serve as anti-cancer and anti-inflammatory agents [25]. Initial attempts to carry out Diels-Alder reactions with these dienophiles under thermal conditions were fruitless.…”

Section: -Phenylthio/phenylselenenyl/ptolylsulphinyl Cycloalkenones Amentioning

confidence: 99%

α-Activated Cross Conjugated Cycloalkenone Systems in Organic Synthesis

Wu¹,

Ly²,

Shia

2010

COS

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Under catalysis with an appropriate Lewis acid, the intermolecular Diels-Alder cycloaddition and intramolecular polyene cyclization of the -activated cross conjugated cycloalkenone systems, possessing particularly increased dienophilicity/electrophilicity in the cross conjugated double bond, proceeded constantly with a high degree of stereochemical control, leading to a variety of synthetically useful molecules, which may serve as advanced intermediates towards many structurally challenging natural products, especially cisclerodane diterpenoids. Mechanistically, an additional conjugated double bond incorporated into the cycloalkenone core of the titled systems might contribute synergistically to the classical secondary orbital effects, thus significantly enhancing the endo-to-ketone addition. In addition, a tandem multiple -bond migration process, an enzymatic pathway prevalent in nature, was proposed to rationalize the formation of structurally unusual polyene-cyclization products occurring under standard chemical conditions.

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Synthetic applications of 2-phenylselenenylenones—III

Cited by 34 publications

References 20 publications

A conjugate addition-dipolar cycloaddition approach towards the synthesis of various alkaloids

A conjugate addition-dipolar cycloaddition approach towards the synthesis of various alkaloids

Total Synthesis of Bis-anthraquinone Antibiotic BE-43472B

α-Activated Cross Conjugated Cycloalkenone Systems in Organic Synthesis

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Synthetic applications of 2-phenylselenenylenones—III

Cited by 34 publications

References 20 publications

A conjugate addition-dipolar cycloaddition approach towards the synthesis of various alkaloids

A conjugate addition-dipolar cycloaddition approach towards the synthesis of various alkaloids

Total Synthesis of Bis-anthraquinone Antibiotic BE-43472B

&#945;-Activated Cross Conjugated Cycloalkenone Systems in Organic Synthesis

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α-Activated Cross Conjugated Cycloalkenone Systems in Organic Synthesis