1515-82-8Relevant academic research and scientific papers
Merging organocatalysis with an indium(III)-mediated process: A stereoselective α-alkylation of aldehydes with allylic alcohols
Capdevila, Montse Guiteras,Benfatti, Fides,Zoli, Luca,Stenta, Marco,Cozzi, Pier Giorgio
supporting information; experimental part, p. 11237 - 11241 (2010/11/04)
Curiosity killed the CAT..ions! The use of stabilized cationic intermediates can be considered as a new frontier in the development of stereoselective reactions. An organocatalytic procedure mediated by the MacMillan imidazolidinone catalyst was coupled with an InBr3-mediated process for the development of a novel stereoselective allylation reaction of aldehydes. Up to 98 % ee and up to 5:1 d.r. were obtained in the process.
Reactivity of individual organolithium aggregates: A RINMR study of n-butyllithium and 2-methoxy-6-(methoxymethyl)phenyllithium
Jones, Amanda C.,Sanders, Aaron W.,Bevan, Martin J.,Reich, Hans J.
, p. 3492 - 3493 (2008/01/01)
Low-temperature rapid injection NMR (RINMR) experiments were performed on two lithium reagents, n-butyllithium and 2-methoxy-6-(methoxymethyl)phenyllithium (5), with the goal of measuring the relative reactivity of the different aggregates (dimer, mixed dimer, and tetramer for n-BuLi, monomer and tetramer for 5) toward typical electrophiles. The reaction of the n-BuLi dimer with (trimethylsilyl)acetylene first forms the mixed dimer n-BuLi·Me3SiC≡CLi, which is about 1/60 as reactive as the n-BuLi homodimer. The tetramer does not react. In the deprotonation of (phenylthio)acetylene, the n-BuLi dimer was found to be 3.5 × 108 as reactive as the tetramer, and in the addition to p-diethylaminobenzaldehyde, the relative reactivity was at least 2 × 104. In the deprotonation of (p-tolylsulfonyl)acetylene, the monomer of 5 was at least 1014 times as reactive as the tetramer. These measurements show that the difference in reactivity between the lower and higher aggregates of organolithium reagents can be many orders of magnitude higher than all previous estimates. Copyright
[1,2]-Wittig rearrangement from chloromethyl ethers
Gómez, Cecilia,Maciá, Beatriz,Lillo, Victor J.,Yus, Miguel
, p. 9832 - 9839 (2007/10/03)
The reaction of different chloromethyl ethers 1 with an excess of lithium powder and a catalytic amount of 4,4′-di-tert-butylbiphenyl (2.5 mol %) in THF at 0 °C leads to the corresponding α-lithiomethyl ether intermediates, through a chlorine-lithium exchange, which spontaneously undergo a clean [1,2]-Wittig rearrangement affording the expected homobenzylic alcohols 2. This is the first version of this rearrangement starting from easily available chloromethyl ethers.
The total synthesis of coleophomones B, C, and D
Nicolaou,Montagnon, Tamsyn,Vassilikogiannakis, Georgios,Mathison, Casey J. N.
, p. 8872 - 8888 (2007/10/03)
Members of the coleophomone family of natural products all possess several intriguing and challenging architectural features, as well as exhibit unusual biological activity. They, therefore, constitute attractive targets for synthesis. In this Article, we describe the total synthesis of coleophomones B (2), C (3), and D (4). The highly strained and congested 11-membered macrocycle of coleophomones B (2) and C (3) was constructed using an impressive olefin metathesis reaction. Furthermore, both of the requisite geometric isomers of the Δ within the macrocycle could be accessed from a common precursor, facilitating a divergence that lent the coleophomone B (2)/C (3) synthesis an unusually high degree of efficiency. The synthesis of coleophomone D (4) confirmed that it exists as a dynamic mixture of isomeric forms with a different aromatic substitution pattern from the other family members.
Oxidation of benzylic alcohols and ethers to carbonyl derivatives by nitric acid in dichloromethane
Strazzolini, Paolo,Runcio, Antonio
, p. 526 - 536 (2007/10/03)
Nitric acid in dichloromethane may be successfully employed for the oxidation of benzylic alcohols and ethers to the corresponding carbonyl compounds. The proposed method proved to be of general applicability, affording very good yields of aldehydes and ketones and showing interesting chemoselectivity in many instances, allowing competitive aromatic nitration to be avoided, as well as - in the case of aldehydes - any further oxidation to carboxylic acids. The reaction probably proceeds by a radical mechanism, the active species in the oxidation process being NO2. Competitive formation of nitro esters was observed in some cases, whereas poor results were obtained with allylic and non-benzylic substrates. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003.
Reductive etherification of aromatic aldehydes with decaborane
Lee, Seung Hwan,Park, Yong June,Yoon, Cheol Min
, p. 6049 - 6050 (2007/10/03)
Aromatic aldehydes were easily convened to the corresponding ethers in methanol or ethanol using decaborane at r.t. under nitrogen in high yields.
SUBSTITUENT EFFECTS IN THE PHOTOSOLVOLYSIS OF BENZYL DERIVATIVES. GENERAL STRUCTURE-REACTIVITY RELATIONSHIPS.
Wan, Peter,Chak, Becky,Li, Carrier
, p. 2937 - 2940 (2007/10/02)
The relative reactivity of photosolvolysis of a number of substituted benzyl acetates is in the order ortho > meta > para, these substitutent effects being apparently additive, as suggested by the relative reactivity of photomethanolysis of several dimethoxy-susbstituted benzyl alcohols.
Structure-Reactivity Studies and Catalytic Effects in the Photosolvolysis of Methoxy-substituted Benzyl Alcohols
Wan, Peter,Chak, Becky
, p. 1751 - 1756 (2007/10/02)
The photosolvolysis of several methoxy-, dimethoxy-, and hydroxy-substituted benzyl alcohols has been studied in aqueous solution.The primary photochemical event is photodehydroxylation, to give a benzyl cation intermediate, which can be trapped by added external nucleophiles.The reaction is via the singlet excited state, based on observation of fluorescence quenching by hydronium ion in a complementary manner with acid catalysis of reaction observed for several derivatives.Solvent isotope effects on fluorescence efficiency and reaction for (7) and (8) provide additional support of singlet-state reactivity for these compounds.Dimethoxy-substituted alcohols are more reactive than monosubstituted compounds, with quantum yields of methanolysis of up to 0.31 for the most reactive compound, 2,6-dimethoxybenzyl alcohol (8).Using a kinetic argument, the quantum yields of the primary photodehydroxylation process has been estimated to be 1.0 +/- 0.1 for this compound.The results observed for the dimethoxy-substituted derivatives suggest the existence of additivity of substituent effects in these photodehydroxylation reactions.
A Convenient Synthesis of 7-Methoxyisochroman-3-one
Khanapure, Subhash P.,Bhawal, B. M.,Hazra, Braja G.
, p. 889 - 890 (2007/10/02)
m-Methoxybenzyl methyl ether (2), on chloromethylation affords chloromethylation product (3) which on treatment with potassium cyanide furnishes a mixture of isomeric cyano compounds (4).Acid hydrolysis of 4 provides besides the title compound (5) in 46pe
