27980-52-5Relevant academic research and scientific papers
Iodine-catalyzed transformation of aryl-substituted alcohols under solvent-free and highly concentrated reaction conditions
Jereb, Marjan,Vra?i?, Dejan
, p. 747 - 762 (2018/01/17)
Iodine-catalyzed transformations of alcohols under solvent-free reaction conditions (SFRC) and under highly concentrated reaction conditions (HCRC) in the presence of various solvents were studied in order to gain insight into the behavior of the reaction intermediates under these conditions. Dimerization, dehydration and substitution were the three types of transformations observed with benzylic alcohols. Dimerization and substitution reactions were predominant in the case of primary- and secondary alcohols, whereas dehydration prevailed in the case of tertiary alcohols. The relative reactivity of substituted 1-phenylethanols in I2-catalyzed dimerization under SFRC provided a good Hammett plot ρ+ = -2.8 (r2 = 0.98), suggesting the presence of electron-deficient intermediates with a certain degree of developed charge in the rate-determining step.
Pd-Catalyzed Autotandem Reactions with N-Tosylhydrazones. Synthesis of Condensed Carbo- and Heterocycles by Formation of a C-C Single Bond and a C-C Double Bond on the Same Carbon Atom
Paraja, Miguel,Valdés, Carlos
, p. 2034 - 2037 (2017/04/27)
A new Pd-catalyzed autotandem reaction is introduced that consists of the cross-coupling of a benzyl bromide with a N-tosylhydrazone followed by an intramolecular Heck reaction with an aryl bromide. During the process, a single and a double C-C bond are formed on the same carbon atom. Two different arrangements for the reactive functional groups are possible, rendering great flexibility to the transformation. The same strategy led to 9-methylene-9H-fluorenes, 9-methylene-9H-xanthenes, 9-methylene-9,10-dihydroacridines, and also dihydropyrroloisoquinoline and dihydroindoloisoquinoline derivatives.
Synthesis and Wagner-Meerwein rearrangement of 9-(α-hydroxyalkyl) xanthenes to 10-substituted dibenz[b,f]oxepins: Scope, limitations and ab initio calculations
Storz, Thomas,Vangrevelinghe, Eric,Dittmar, Peter
, p. 2562 - 2570 (2007/10/03)
A series of 9-(hydroxy)alkyl xanthenes 5 was prepared in good yields via: (a) addition of 9-lithioxanthene to functionalized acetaldehydes, or, via a new method, (b) addition of carbanions to xanthene-9-carbaldehyde. A practical and efficient synthesis wa
Facile synthesis of 1,2-diaryl- and triarylethenes with supported fluoride bases
Hellwinkel,Goke,Karle
, p. 973 - 978 (2007/10/02)
Differently substituted arenecarbaldehydes, mainly benzaldehydes, can be very efficiently condensed with a wide variety of methylbenzenes having an electron-withdrawing group in the para-position, as well as with fluorenes, xanthene, cyclopentadienes and indenes by using a standardized KF- or CsF-Al2O3 base system in dimethylformamide.
Unstable Compounds. Synthesis and Experimental and Computational Study of the Chemical Behavior of 9--9-xanthydrol
Badejo, Ibraheem T.,Karaman, Rafik,Fry, James L.
, p. 4591 - 4596 (2007/10/02)
The title alcohol (1) was synthesized in good yield by a novel umpolung method involving reaction of the lithium dianion of 9-xanthone with tropylium ion.It was prepared to see if its derived carbenium ion might undergo spontaneous α fragmentation to form tropylium ion and singlet-state xanthylidene.In contrast to expectation, treatment of 1 with Broensted and Lewis acids under a variety of experimental conditions produced 9-benzylidenexanthene (8) as the exclusive dehydration product.Stable ion and trapping studies established that the 9-benzyl-9-xanthyl cation was the immediate precursor of 8.When this cation was generated from 1 or 8 and trapped with triethylsilane-d1, 9-benzylxanthene-9-d1 was produced with primary deuterium kinetic isotope effects of 1.27 +/- 0.07 and 1.28 +/- 0.07, respectively.The energy surfaces leading to contraction of the cycloheptatrienyl ring to the phenyl ring were explored by molecular mechanics and MNDO calculations.The computational results indicated that the most probable mechanism involved the intervention of a phenonium ion intermediate but not a tropylium ion.It was estimated that the activation energy of the reaction pathway leading to the observed ring-contracted product was ca. 31.0 kcal/mol lower than that of the unobserved α-fragmentation route (40.1 vs 71.1 kcal/mol).
Organic Reactive Intermediates: Part XI - Preparation and Reactions of Xanthenyl Ylids
Handoo, Kishan L.,Kaul, Anju
, p. 1 - 2 (2007/10/02)
Two new xanthenyl ylids, viz. triphenylphosphoniumxanthen-9-ylid and triphenylphosphoniumthioxanthen-9-ylid have been prepared.The former undergoes normal Wittig reaction with a number of carbonyl compounds yielding olefins.
Reaction of Olefins with Malonamide in the Presence of Manganese(III) Acetate. Formation of α,β-Unsaturated γ-Lactones and γ-Lactams
Nishino, Hiroshi
, p. 217 - 222 (2007/10/02)
The reaction of olefins with malonamide in the presence of manganese(III) acetate gave 2-buten-4-olides and/or 1H-pyrrol-2(5H)-ones in one-step, short reaction time and moderate yields.The product distribution can be accounted for in terms of the stabilization of the intermediate carbocation in the oxidation process.The synthetic application and limitation, and the oxidation mechanism for the formations of α,β-unsaturated γ-lactones and γ-lactams are discussed.
Studies on Betaine Decomposition of Arsonium Ylides
Tewari, R. S.,Suri, S. K.,Gupta, K. C.
, p. 95 - 98 (2007/10/02)
A systematic study on the nature of decomposition of betaine formed by nucleophilic attack of semistabilized arsonium ylides on thiocarbonyl substrates has been carried out.A series of substituted benzylidenetriphenylarsenanes have been generated from their corresponding salts and condensed with few cyclic thioketones to yield exocyclic olefins as exclusive products.The non-availability of thioepoxides indicates that the mode of decomposition of such type of betaines is quite analogous to the betaine formed by phosphonium ylides.The structure of the products have been assigned by IR and NMR spectral studies. - Keywords: Betaine, Arsonium Ylides
