590-38-5Relevant academic research and scientific papers
ALKYNYLALUMINIUM COMPOUNDS IV. REACTIONS OF DIMETHYLALKYNYLALUMINIUM COMPOUNDS WITH KETONES
Starowieyski, K. B.,Becalska, A.
, p. 223 - 230 (1984)
The addition of dimethylpropynyl-, dimethylbutynyl- and dimethylphenylethynyl-aluminium to acetone and acetophenone leads to the products of alkynylation, but the methylated products are also formed.The selectivity of the alkynylaluminium compounds used in alkynylation increases in order (Me2AlCCEt)2 CMe)2 , (Me2AlCCPh)2.The selectivity increases when an excess of the organoaluminium compound is used, or when it is applied as a complex with a Lewis base.An increase of reactivity of the investigated compounds toward ketones in order (Me3Al)2 CMe)2 CEt)2 is observed.
Synthesis of Isoquinolines through IrIII-Catalyzed C–H Activation/Annulation from Benzimidates with Hydroxylisopropylalkynes
Liu, Mingliang,Gong, Wanchun,You, Erli,Zhang, Haizhen,Shi, Lei,Cao, Weiguo,Shi, Jingjing
supporting information, p. 4991 - 4995 (2018/10/05)
An IrIII-catalyzed cascade reaction consisting of C–H activation/annulation of benzimidates with hydroxylisopropylalkynes is reported. A broad range of isoquinolines has been prepared in one step with good functiona-group tolerance and high eff
Synthesis and Utility of 2,2-Dimethyl-2 H-pyrans: Dienes for Sequential Diels-Alder/Retro-Diels-Alder Reactions
Tejedor, David,Díaz-Díaz, Abián,Diana-Rivero, Raquel,Delgado-Hernández, Samuel,García-Tellado, Fernando
supporting information, p. 7987 - 7992 (2019/01/04)
The practical use of 2,2-dimethyl-2H-pyrans as electron-rich dienes in sequential Diels-Alder/retro-Diels-Alder (DA/rDA) domino processes to generate aromatic platforms has been demonstrated. Different polysubstituted alkyl 2-naphthoates have been synthesized by the DA/rDA reaction of benzynes and 2,2-dimethyl-2H-pyrans. The use of other activated alkynes allows the access of substituted alkyl benzoate derivatives.
Synthesis of β-sulfanyl ketones via a tandem rearrangement-conjugate addition reaction catalyzed by a Re(V)-oxo complex
Garst, Alyson E.,Badiceanu, Alexandra D.,Nolin, Kristine A.
supporting information, p. 459 - 461 (2013/02/23)
A method for synthesizing β-sulfanyl ketones via a tandem rearrangement and conjugate addition reaction has been developed. This methodology provides access to a range of β-sulfanyl ketones through the rearrangement of propargyl alcohols to the corresponding enones followed by the conjugate addition of unactivated thiols. The one-pot, tandem transformation is catalyzed by ReOCl3(OPPh3)(S(CH3)2) affording aryl and alkyl β-sulfanyl ketones in good to excellent yield.
Solvolytic Reactions in Fluorinated Alcohols. Role of Nucleophilic and Other Solvation Effects
Bentley, T. William,Llewellyn, Gareth,Ryu, Zoon Ha
, p. 4654 - 4659 (2007/10/03)
Rate constants and products for solvolyses of chlorodiphenylmethane (Ph2CHCl) and p-methoxybenzyl chloride in 2,2,2-trifluoroethanol (TFE)/water and TFE/ethanol are reported, along with additional kinetic data for solvolyses of tert-butyl and other alkyl halides (RX) in 97% w/w TFE/water and in 97% w/w hexafluoropropan-2-ol/water (HFIP). Results are discussed in terms of the solvent ionizing power (Y) and the solvent nucleophilicity (N), and contributions from other solvation effects are considered. Comparisons with other SN1 solvolyses show that solvolyses of Ph2CHCl in TFE mixtures are unexpectedly fast, but product ratios are unexceptional. An additional solvation effect influences solvolyses leading to delocalized cations, and a delocalized cationic transition state for concerted elimination may explain the recent results of Takeuchi et al., (J. Org. Chem. 1997, 62, 4904) without the need to postulate additional specific solvation effects for adamantyl systems, such as Bronsted-base solvation of α- and β-hydrogen atoms; concerted elimination may occur because simple tertiary alkyl cations are too unstable to form in predominantly aqueous media. Iodide/bromide and bromide/chloride rate ratios are very similar for 1-adamantyl halides and corresponding solvolyses of tert-butyl halides; these ratios decrease in the order aq EtOH > TFE > HFIP, as expected for an electrophilic solvation effect (this effect can readily be incorporated into Y values). From kinetic data for a series of tertiary alkyl chlorides in 97% TFE/water, it is shown that the susceptibility of rates of solvolyses of RCl to N decreases with an increase in steric hindrance or with an increase in charge stabilization. Also, the small kinetic solvent isotope effects for typical solvolyses (e.g., methyl tosylate) indicate that nucleophilic attack lags behind heterolysis of the C-X bond.
Convenient synthesis of 4-methylene-2-oxazolidinones and 4-methylenetetrahydro-1,3-oxazin-2-ones via transition-metal catalyzed intramolecular addition of nitrogen atom to actylenic triple bond
Tamaru,Kimura,Tanaka,Kure,Yoshida
, p. 2838 - 2849 (2007/10/02)
2-Propynyl tosylcarbamates 1 undergo cyclization smoothly by the catalysis of CuCl/Et3N or AgNCO/Et3N to furnish 4-methylene-2-oxazolidinones 2 in good yields. The similar cyclization of the N-acyl derivatives of 1 (PhCO, MeCO, EtOCO, etc.) is catalyzed effectively by AgNCO/t-BuOK. These reactions accommodate a variety of substituents at C1 and C3 of 2-propyn-1-ol and provide (Z)-2 as single stereoisomers. The scope of the cyclization of 3-butynyl carbamates is rather limited, and in general only N-tosyl derivatives of terminally unsubstituted 3-butyn-1-ols undergo cyclization to give 4-methylenetetrahydro-1,3-oxazin-2-ones in synthetically useful yields by the catalysis of AgNCO/Et3N or AgNCO/t-BuOK.
Convenient generation of 1-propynyllithium. One-pot synthesis of acetylenic carbinols from 1,2-dibromopropane and aldehydes and ketones
Gribble,Joyner,Switzer
, p. 2997 - 3002 (2007/10/02)
Treatment of 1,2-dibromopropane (1) with 3 equiv of lithium diisopropylamide (-60° to 0°C, THF) generates 1-propynyllithium (2), which with aldehydes or ketones affords acetylenic carbinols 3 in 82-96% yields.
Cycloaddition Reactions of Allenyl Cations with Cyclopentadiene
Mayr, Herbert,Halberstadt-Kausch, Inge K.
, p. 3479 - 3515 (2007/10/02)
Propargyl halides R1-C=-C-CR2R3X (14) and cyclopentadiene react with zinc halide catalysis in ether/dichloromethane solution to give 3-halogenobicycloocta-2,6-dienes 13 (R1 = alkyl) or 5-(α-halogenobenzylidene)norbornenes 15 (R1 = aryl).The reactions are interpreted by stepwise - and -cycloadditions of intermediate allenyl cations 1, proceeding via propargylcyclopentenyl cations 5 and bicyclic vinyl cations 9 or 12.If the reactions are initiated by equimolar amounts of silver trifluoroacetate, quenching products of all postulated intermediates are isolated.The relative energies of the intermediate carbenium ions are estimated on the basis of force field calculations and of gas phase stabilities of simple carbocations.Stereochemical studies indicate that the addition reactions proceed via the compact transition state 42 rather than 41.The zinc chloride catalysed reaction of propargyl chloride 14e with cyclopentadiene yields the 2:1 product 17 (structurally assigned by X ray analysis) in addition to the 1:1 product 15e.The formation of 17 is rationalised by a -cycloaddition of allenyl cation 1 with cyclopentadiene.
Cycloadditions of Allyl Cations, 22. Allyl Alcohols as Precursors of Allyl Cations
Hoffmann, H. M. R.,Matthei, Juergen
, p. 3837 - 3847 (2007/10/02)
Allyl alcohols such as 3-ethoxy-2-methyl-3-buten-2-ol (4), the silylated alcohol 8 and also 2-methyl-3-pentyn-2-ol (12) have been converted into the corresponding trifluoroacetates (5, 9, 13), which in the presence of zinc halide/ethyldiisopropylamine react with conjugated dienes to form bridged seven-membered rings (14, 16, 18, 20 - 24) in good to excellent yields.Thus, unlike all other oxyallyl precursors studied so far, 5 gives the bridged 1-ethoxy-1,4-cycloheptadiene (14, 16, 18, 20) under the present conditions rather than the thermodynamically more stable 4-cyclohep ten-1-one (15, 17, 19, 21) which is formed from the initial enol ether by hydrolysis.It is concluded that structurally complex allyl cations can now be generated in very mild conditions, and owing to the presence of ethyldiisopropylamine, even in weakly alkaline solutions.
