83043-84-9Relevant articles and documents
Synthesis of Cyclobutene-Fused Eight-Membered Carbocycles through Gold-Catalyzed Intramolecular Enyne [2+2] Cycloaddition
Iwai, Tomohiro,Ueno, Masahiro,Okochi, Hiori,Sawamura, Masaya
supporting information, p. 670 - 675 (2017/12/26)
Cationic gold(I) complexes with hollow-shaped triethynylphosphine ligands efficiently catalyzed intramolecular [2+2] cycloaddition of 1,9-enynes to afford cyclobutene-fused eight-membered carbocycles that were difficult to synthesize by other catalytic systems. Various 1,9-enynes with carbon linkers with or without a fused ring underwent efficient [2+2] cycloaddition with 5 mol% of the Au catalyst bearing the triarylmethyl-end-capped triethynylphosphine in CH2Cl2 at rt in the presence of MS 4A as an additive. More challenging 1,9-enyne substrates with fully saturated acyclic carbon linkers underwent eight-membered ring formation at 60 °C in ClCH2CH2Cl in the absence of MS 4A, forming monocyclic 1,3-dienes as major products. (Figure presented.).
Modular Construction of Fluoroarenes from a New Difluorinated Building Block by Cross-Coupling/Electrocyclisation/Dehydrofluorination Reactions
Percy, Jonathan M.,Emerson, Helena,Fyfe, James W. B.,Kennedy, Alan R.,Maciuk, Sergej,Orr, David,Rathouská, Lucie,Redmond, Joanna M.,Wilson, Peter G.
, p. 12166 - 12175 (2016/08/16)
Palladium-catalysed coupling reactions based on a novel and easy-to-synthesise difluorinated organotrifluoroborate were used to assemble precursors to 6π-electrocyclisations of three different types. Electrocyclisations took place at temperatures between 90 and 240 °C, depending on the central component of the π-system; nonaromatic trienes were most reactive, but even systems that required the temporary dearomatisation of two arenyl subunits underwent electrocyclisation, albeit at elevated temperatures. Photochemical conditions were effective for these more demanding reactions. The package of methods delivered a structurally diverse set of fluorinated arenes, spanning a 20 kcal mol?1range of reactivity, by a flexible route.
Formation of enehydrazine intermediates through coupling of phenylhydrazines with vinyl halides: Entry into the Fischer indole synthesis
Zhan, Fuxu,Liang, Guangxin
supporting information, p. 1266 - 1269 (2013/03/13)
Cut to the chase: Direct formation of an enehydrazine, an intermediate in the classic Fischer indole synthesis, solves the regioselectivity problem associated with indolization. This approach not only achieves selective synthesis of indoles through proper selection of the vinyl halide, but also leads to quick construction of desoxyeseroline and esermethole, as well as the key structural motif in the Akuammiline alkaloid vincorine. Copyright
Gold-catalyzed oxidative cyclizations of cis-3-En-1-ynes to form cyclopentenone derivatives
Bhunia, Sabyasachi,Ghorpade, Satish,Huple, Deepak B.,Liu, Rai-Shung
, p. 2939 - 2942 (2012/05/20)
Golden tendencies: The title reaction for synthesizing cyclopentenone derivatives utilizes a gold complex and 8-methylquinoline oxide as the catalyst system (see scheme; IPr=1,3-bis(diisopropylphenyl)imidazol-2-ylidene). Such products are not attainable using diazocarbonyl reagents, as the gold carbenoids tend to react with C-H bonds. Copyright
Thermally induced cyclobutenone rearrangements and domino reactions
Harrowven, David C.,Pascoe, David D.,Guy, Ian L.
, p. 425 - 428 (2008/02/02)
(Chemical Equation Presented) Four thermal-rearrangement pathways and a domino reaction leading to quinones arise from the thermolysis of cyclobutenones. The course of vinylcyclobutenone rearrangements is dictated by the nature of the substituent, R (see
Palladium-catalyzed carbonylative cyclization of unsaturated aryl iodides and dienyl triflates, iodides, and bromides to indanones and 2-cyclopentenones
Gagnier, Steve V.,Larock, Richard C.
, p. 4804 - 4807 (2007/10/03)
Indanones and 2-cyclopentenones have been successfully prepared in good to excellent yields by the palladium-catalyzed carbonylative cyclization of unsaturated aryl iodides and dienyl triflates, iodides, and bromides, respectively. The best results are obtained by employing 10 mol % of Pd(OAc)2, 2 equiv of pyridine, 1 equiv of n-Bu4NCl, 1 atm of CO, a reaction temperature of 100 °C, and DMF as the solvent. This carbonylative cyclization is particularly effective on substrates that contain a terminal olefin. The proposed mechanism for this annulation includes (1) Pd(OAc)2 reduction to the active palladium(0) catalyst, (2) oxidative addition of the organic halide or triflate to Pd(0), (3) coordination and insertion of carbon monoxide to produce an acylpalladium intermediate, (4) acylpalladation of the neighboring carbon-carbon double bond, (5) reversible palladium β-hydride elimination and re-addition to form a palladium enolate, and (6) protonation by H2O to produce the indanone or 2-cyclopentenone.
A one-pot sequence of Stille and Heck couplings: Synthesis of various 1,3,5-hexatrienes and their subsequent 6π-electrocyclizations
Von Zezschwitz, Paultheo,Petry, Frauke,De Meijere, Armin
, p. 4035 - 4046 (2007/10/03)
Palladium-catalyzed crosscoupling reactions of 2-bromocyclohex1-enyl triflates 7 and 11 with a variety of alkenylstannanes occurred chemoselectively at the site of the triflate leaving group to give bromobutadienes which readily underwent Heck reactions w
A STUDY OF PERISELECTIVITY IN THE THERMAL CYCLISATION REACTIONS OF DIENE-CONJUGATED DIAZO COMPOUNDS: 1,7-CYCLISATION AS A ROUTE TO 3H-1,2-DIAZEPINES AND 1,5-CYCLISATION LEADING TO NEW REARRANGEMENT REACTIONS OF 3H-PYRAZOLES
Robertson, Ian R.,Sharp, John T.
, p. 3095 - 3112 (2007/10/02)
A range of diene-conjugated diazo compounds has been generated by the thermal decomposition of the sodium salts of the tosylhydrazones of 1-acyl-1,3-dienes. Those of type (21) with a cis relationship of the diazo group and the γ,δ-double bond and having a cis hydrogen atom at the dien terminus cyclised only by 1,7 ring closure to give 3H-1,2-diazepines (23).This mode of cyclisation was inhibited by the presence of cis methyl or phenyl groups at the diene terminus eg in (45). Compounds of this type cyclised by the alternative 1,5- ring closure to give 3-alkenyl-3H-pyrazoles eg (46) as primary products. These observations are explained on the basis of a helical transition state (54) for the 8? electron 1,7-electrocyclisation reaction. Diene-conjugated diazo compounds with a trans γ,δ double bond eg (32) also cyclised predominantly by 1,5-electrocyclisation to give 3-alkenyl-3H-pyrazoles eg (33). In most cases the 3H-pyrazoles rearranged under the reaction conditions via alkenyl group and hydrogen migrations to give 1H-pyrazoles eg (34) and (37).
12-s-Cis Conformationally Locked 11cis-Retinoids: A Delineation of the Thermal Requirements for -Sigmatropic Shifts and Electrocyclizations in the Vitamin A Series and Novel Spectral Properties
Chandraratna, Roshantha, A. S.,Bayerque, Ann L.,Okamura, William H.
, p. 3588 - 3594 (2007/10/02)
The thermally induced -sigmatropic rearrangement (69 deg C, 4 h) of the six-membered ring fused vinylallenol 5b, a process specific for preparing 11-cis-retinoids, afforded 24 (12percent) and the 12-s-cis-locked retinols 11-cis-7a (14percent), 11-cis
