5770-68-3Relevant academic research and scientific papers
A facile synthesis of 2-hydroxy-2-aryl 1,4-benzodioxanes
Ganesh,Harish Kumar,David Krupadanam
, p. 2069 - 2078 (2007/10/03)
Condensation of catechol with 2-bromo-1-aryl-ethanones and 2-bromo-1- aryl-propanones in dry acetone-K2CO3 medium afforded 2-hydroxy-2-aryl-1,4- benzodioxanes in good yield.
Clean synthesis of α-bromo ketones and their utilisation in the synthesis of 2-alkoxy-2,3-dihydro-2-aryl-1,4-benzodioxanes, 2-amino-4-aryl-1,3-thiazoles and piperidino-2-amino-1,3-thiazoles using polymer-supported reagents
Habermann, Joerg,Levy, Steven V.,Scicinski, Jan J.,Scott, James S.,Smits, Rene,Thomas, Andrew W.
, p. 2425 - 2428 (2007/10/03)
An array of 2-alkoxy-2,3-dihydro-2-aryl-1,4-benzodioxane derivatives and 2-amino-1,3-thiazoles were prepared in high yield using a straightforward three-step and two-step sequence of polymer-supported reagents, respectively and other polymer-supported sequestering reagents without any chromatographic purification step. A key step involves clean and efficient bromination of acetophenones using polymer-supported pyridinium bromide perbromide (PSPBPB) and subsequent cyclisation reaction.
Convenient synthesis of 2,2-disubstituted-2,3-dihydro-1,4-benzodioxins from 2-substituted-2-hydroxy-2,3-dihydro-1,4-benzodioxins
Thiery, Valerie,Coudert, Gerard,Guillaumet, Gerald
, p. 2061 - 2074 (2007/10/03)
Convenient syntheses of relatively rare 2,2-disubstituted-2,3-dihydro-1,4-benzodioxins from 2-substituted-2-hydroxy-2,3-dihydro-1,4-benzodioxins, as key synthetic intermediates, are reported. These new synthetic approaches require Lewis acid BF3-Et2O mediated nucleophilic substitution reaction or cyclization of suitable hydroxyphenols.
ACYLOTROPIC REARRANGEMENT OF o-ACYLOXYPHENOXYACETONES
Dzvinchuk, I. B.,Lozinskii, M. O.
, p. 1146 - 1152 (2007/10/02)
A new type of intramolecular ester Claisen condensation, i.e., the alkali-catalyzed O,C--acylotropic rearrangement of o-acyloxyphenoxyacetones, is described.The reaction leads to the products from intramolecular cyclization or alkaline hydrolysis of
EFFECT OF PROPERTIES OF THE MEDIUM AND ELECTRONIC EFFECTS OF SUBSTITUENTS ON RING-CHAIN TAUTOMERISM IN 2-ARYL-2-HYDROXY-2,3-DIHYDRO-1,4-BENZODIOXINS
Dzvinchuk, I. B.,Lozinskii, M. O.
, p. 1954 - 1961 (2007/10/02)
The constants of the ring-chain tautomeric equilibrium in 2-aryl-2-hydroxy-2,3-dihydro-1,4-benzodioxins in various solvents were measured by PMR.The experimental data treated by means of the Palm-Koppel and Yukawa-Tsuno equations, indicate that the position of the equilibrium is determined by the joint effect of such characteristics of the medium as polarity, polarizability, and particularly general basicity and also by the electron-deficiency at the carbonyl carbon atom of the noncyclic tautomer.A tendency was found for the reaction constant to decrease and the resonance stabilization of the noncyclic tautomer to increase with increase in the nucleophilic characteristics of the solvent.
STRUCTURE OF THE PRODUCTS OF THE O-MONOALKYLATION OF PYROCATECHOL BY α-BROMOKETONES
Dzvinchuk, I.B.,Kuznetsov, N.V.,Lozinskii, M.O.
, p. 386 - 389 (2007/10/02)
The reaction of pyrocatechol with α-bromoketones in the presence of triethylamine leads to the formation of o-hydroxyphenoxymethyl ketones or 2-hydroxy-2,3-dihydro-1,4-benzodioxines.PMR spectroscopy revealed ring-chain tautomerism of the products obtained
α-Adrenoreceptor Reagents. 3. Synthesis of Some 2-Substituted 1,4-Benzodioxans as Selective Presynaptic α2-Adrenoreceptor Antagonists
Stillings, Michael R.,Chapleo, Christopher B.,Butler, Richard C. M.,Davis, J. Alfred,England, C. David,et al.
, p. 1054 - 1062 (2007/10/02)
The synthesis and pharmacological activity of a series of 2-substituted derivatives of the selective α2-adrenoreceptor antagonist idazoxan (RX 781094) is described.Substitution in this position by alkyl, alkenyl, cycloalkenyl, and alkoxy groups in many cases gives compounds whose potencies and selectivities are significantly greater than those of the parent compound.
Synthesis, Thermal Stability, and Chemiluminescence Properties of the Dioxetanes Derived from 1,4-Dioxines
Adam, Waldemar,Peters, Eva-Maria,Peters, Karl,Platsch, Herbert,Schmidt, Ernst,et al.
, p. 3920 - 3928 (2007/10/02)
Photosensitized oxygenation of benzo- and naphtho-1,4-dioxins 3 afforded the corresponding 1,2-dioxetanes 4 in moderate to good yields.Ene products 7 were obtained in those cases in which the 1,4-dioxins 3 bear alkyl substituents.Thermal decomposition of the 1,2-dioxetanes 4 afford the corresponding diesters 5 essentially quantitatively.The X-ray crystal structures of the dioxetanes 4g, 4h, and 4j indicate that the four-membered rings are all essentially planar.These dioxetanes exhibit surprisingly similar thermal stabilities; the free energies of activation (ΔG(excit.)) at 298 K fall within 26 +/- 1 kcal/mol, the enthalpies of activation (ΔH(excit.)) within 24 +/- 1.5 kcal/mol, and the entropies of activation (ΔS(excit.)) within -6 +/- 2 eu.In their chemiluminescence properties they are inefficient sources of chemienergized, electronically excited diester products.The singlet excitation yields (ΦS) range between 0.0001percent and 0.003percent and the triplet excitation yields (ΦT) between 0.01percent and 3.5percent.They represent typical dioxetanes in that preferentially triplet excited carbonyl products are chemienergized.
