62-23-7Relevant articles and documents
1,4-DIAMINO-1,4-DIDEOXY-D-GALACTITOL AND 1,5-DIAMINO-1,5-DIDEOXY-L-ALTRITOL
Kuszmann Janos
, p. 25 - 38 (1986)
The mesyloxy group of 1-azido-1-deoxy-4-O-mesyl-D-glucitol could be displaced by azide, in the 2,3:4,5-di-O-isopropylidene derivative 4 or tetraacetate, yielding, after removal of the protecting groups, 1,4-diazido-1,4-dideoxy-D-galactitol (7).The 2,3- (10( and 5,6-O-isopropylidene derivative (13) of 7 gave, on mesylation, the corresponding 5,6- (11) and 2,3-dimesylate (15), respectively.Treatment of 11 with hydrochloric acid yielded 3,6-anhydro-1,4-diazido-1,4-dideoxy-5-O-mesyl-D-galactitol, whereas 15 gave the corresponding 5,6-diol which was converted with base into 2,6-anhydro-1,4-diazido-1,4-dideoxy-3-O-mesyl-D-talitol.Cleavage of the 5,6-O-isopropylidene group of 4 gave 1-azido-1-deoxy-2,3-O-isopropylidene-4-O-mesyl-D-glucitol, which could be converted via the corresponding 4,5-epoxide into 1,5-diazido-1,5-dideoxy-2,3-O-isopropylidene-L-altritol (25).The 6-p-nitrobenzoates of 25 and 13 are derivatives suitable for the synthesis of sorbistin analogues.Reductionof the corresponding deprotected diazides afforded the title compound.
Studies on a dithiane-protected benzoin photolabile safety catch linker for solid-phase synthesis
Hong Boon Lee,Balasubramanian
, p. 3454 - 3460 (1999)
Substituted benzoinyl systems 8a-g, differing either in the substitution pattern, type of resin matrix used, or resin loading capacity, were prepared and the kinetics of their photolytic cleavage of Fmoc-β-alanine examined on resin. The linker systems 6a-g were assembled in near-quantitative yield using Corey-Seebach dithiane addition. The dithiane group that serves as a safety catch against premature photoreaction was removed by either oxidation or alkylation. Analytical methods that include FTIR and 13C gel-phase NMR spectroscopy were used for rapid reaction monitoring and sample characterization on resin. A survey of different substituted systems 8c-f for releasing Fmoc-β-alanine confirmed that the 3-alkoxybenzoin linker photocleaves most rapidly to give the highest yield (τ(1/2) = 6.7 min; 98% yield). Lowering the resin loading from 0.59 mmol/g in 8a to 0.26 mmol/g in 8b improved the cleavage kinetics to τ(1/2) = 2.6 min, 92% yield. Tentagel resin 8g exhibits similar photocleavage kinetics in both organic and aqueous media and when compared to the polystyrene counterpart, 8a. The 3- alkoxybenzoin linker 6a was also loaded with aryl carboxylic acids (12h,i) and hindered Fmoc-protected amino acids (12j-l) with varying degrees of success (57-100%) and dithiane deprotected (70-80%, 13h-1) followed by photocleavage with comparable efficiencies (8993% after 60 min).
Synthesis of 18O-labelled alcohols from unlabelled alcohols
Beddoe, Rhydian H.,Edwards, Daniel C.,Goodman, Louis,Sneddon, Helen F.,Denton, Ross M.
, p. 6480 - 6483 (2020)
The synthesis of primary, secondary and tertiary 18O-enriched alcohols from readily available 16O-alcohols via a Mitsunobu esterification and hydrolysis is described. The method is further exemplified in the labelling of the active pharmaceutical ingredient, dropropizine and is shown to be tolerant of modern, separation friendly Mitsunobu reagents. This journal is
2-(5-Arylterphenyl-4-yl)quinolines from 2-methylquinoline and 1-(het)aryl-3-phenylprop-2-yn-1-ones in just a one step: A miracle of molecular interplay
Trofimov, Boris A.,Belyaeva, Kseniya V.,Nikitina, Lina P.,Afonin, Andrei V.,Vashchenko, Alexander V.
, p. 267 - 269 (2018)
2-Methylquinoline reacts with 1-(het)aryl-3-phenylprop-2-yn-1-ones under mild transition metal-free conditions (55–60 °C, 20 mol% KOH, H2O, MeCN) to afford 2-{5’-(het)aryl[1,1’: 3’,1”]terphenyl-4’-yl}quinolines in up to 35% yield. The reaction likely proceeds via the intermediate 1,3-dipole followed by the double nucleophilic vinylation of the methyl group with two molecules of ynone and subsequent elimination of (het)arenecarboxylic acid.
Sodium percarbonate: A convenient reagent for the thermal and sonic oxidative cleavage of α-haloketones
Yang,Cao,Kabalka
, p. 3695 - 3699 (1995)
Sodium percarbonate has been found to be a mild and effective reagent for the oxidative cleavage of α-haloketones to carboxylic acids. Furthermore, the reactions are dramatically accelerated in the presence of ultrasound with significant enhancement in yields.
Novel rearrangement of 4-aroyloxy-3-bromomethyl-2-isoxazolines to 3-aroyloxymethylisoxazoles and a mechanistic study
Chang,Kim
, p. 8499 - 8503 (2000)
Treatment of 4-aroyloxy-3-bromomethyl- and 4-aroyloxy-3-aroyloxymethyl-2-isoxazolines with NaHCO3 in DMF at 120°C gave 3-aroyloxymethylisoxazoles in moderate to good yields. A concerted mechanism is proposed to explain the formation of the rearrangement products. (C) 2000 Elsevier Science Ltd.
Use of ozone for preparing 4-nitrobenzoic acid in a closed process cycle
Galstyan,Tyupalo,Patapenko,Andreev
, p. 1777 - 1779 (2001)
The possibility of preparing 4-nitrobenzoic acid in a closed process cycle by oxidation of 4-nitrotoluene with an ozone air mixture was examined. The optimal conditions of oxidation with multiple use of mother liquors were found, and the conditions for crystallization of 4-nitrobenzoic acid from the reaction mixture were determined. The effects of water, acetic anhydride, and catalyst on the oxidation performed in mother liquors after filtration of the target product were examined.
Transformation of Thioacids into Carboxylic Acids via a Visible-Light-Promoted Atomic Substitution Process
Fu, Qiang,Liang, Fu-Shun,Lou, Da-Wei,Pan, Gao-Feng,Wang, Rui,Wu, Min,Xie, Kai-Jun
supporting information, p. 2020 - 2024 (2022/03/31)
A visible-light-promoted atomic substitution reaction for transforming thiocacids into carboxylic acids with dimethyl sulfoxide (DMSO) as the oxygen source has been developed, affording various alkyl and aryl carboxylic acids in over 90% yields. The atomic substitution process proceeds smoothly through the photochemical reactivity of the formed hydrogen-bonding adduct between thioacids and DMSO. A DMSO-involved proton-coupled electron transfer (PCET) and the simultaneous generation of thiyl and hydroxyl radicals are proposed to be key steps for realizing the transformation.
Efficiency of lithium cations in hydrolysis reactions of esters in aqueous tetrahydrofuran
Harada, Yumi,Hayashi, Kazuhiko,Ichimaru, Yoshimi,Imai, Masanori,Kojima, Yuki,Maeda, Azusa,Nakayama, Kanae,Sugiura, Kirara
, p. 581 - 594 (2021/06/06)
Lithium cations were observed to accelerate the hydrolysis of esters with hydroxides (KOH, NaOH, LiOH) in a water/tetrahydrofuran (THF) two-phase system. Yields in the hydrolysis of substituted benzoates and aliphatic esters using the various hydroxides were compared, and the effects of the addition of lithium salt were examined. Moreover, it was presumed that a certain amount of LiOH was dissolved in THF by the coordination of THF with lithium cation and hydrolyzed esters even in the THF layer, as in the reaction by a phase-transfer catalyst.
Hydrolysis of amides to carboxylic acids catalyzed by Nb2O5
Siddiki,Rashed, Md. Nurnobi,Touchy, Abeda Sultana,Jamil, Md. A. R.,Jing, Yuan,Toyao, Takashi,Maeno, Zen,Shimizu, Ken-Ichi
, p. 1949 - 1960 (2021/03/26)
Hydrolysis of amides to carboxylic acids is an industrially important reaction but is challenging due to the difficulty of cleaving the resonance stabilized amidic C-N bond. Twenty-three heterogeneous and homogenous catalysts were examined in the hydrolysis of acetamide. Results showed that Nb2O5was the most effective heterogeneous catalyst with the greatest yield of acetic acid. A series of Nb2O5catalysts calcined at various temperatures were characterized and tested in the hydrolysis of acetamide to determine the effects of crystal phase and surface properties of Nb2O5on catalytic performance. The high catalytic performance observed was attributed mainly to the facile activation of the carbonyl bond by Lewis acid sites that function even in the presence of basic inhibitors (NH3and H2O). The catalytic studies showed the synthetic advantages of the present method, such as simple operation, catalyst recyclability, additive free, solvent free, and wide substrate scope (>40 examples; up to 95% isolated yield).
