674-82-8Relevant articles and documents
SYNTHESIS OF HIGH CALORIC FUELS AND CHEMICALS
-
Paragraph 0070, (2013/05/23)
In one embodiment, the present application discloses methods to selectively synthesize higher alcohols and hydrocarbons useful as fuels and industrial chemicals from syngas and biomass. Ketene and ketonization chemistry along with hydrogenation reactions are used to synthesize fuels and chemicals. In another embodiment, ketene used to form fuels and chemicals may be manufactured from acetic acid which in turn can be synthesized from synthesis gas which is produced from coal, biomass, natural gas, etc.
Bioinspired total synthesis and human proteasome inhibitory activity of (-)-salinosporamide A, (-)-homosalinosporamide A, and derivatives obtained via organonucleophile promoted bis-cyclizations
Nguyen, Henry,Ma, Gil,Gladysheva, Tatiana,Fremgen, Trisha,Romo, Daniel
scheme or table, p. 2 - 12 (2011/03/23)
A full account of concise, enantioselective syntheses of the anticancer agent (-)-salinosporamide A and derivatives, including (-)-homosalinosporamide, that was inspired by biosynthetic considerations is described. The brevity of the synthetic strategy stems from a key bis-cyclization of a β-keto tertiary amide, which retains optical purity enabled by A1,3-strain rendering slow epimerization relative to the rate of bis-cyclization. Optimization studies of the key bis-cyclization, enabled through byproduct isolation and characterization, are described that ultimately allowed for a gram scale synthesis of a versatile bicyclic core structure with a high degree of stereoretention. An optimized procedure for zincate generation by the method of Knochel, generally useful for the synthesis of salino A derivatives, led to dramatic improvements in side-chain attachment and a novel diastereomer of salino A. The versatility of the described strategy is demonstrated by the synthesis of designed derivatives including (-)-homosalinosporamide A. Inhibition of the human 20S and 26S proteasome by these derivatives using an enzymatic assay are also reported. The described total synthesis of salino A raises interesting questions regarding how biosynthetic enzymes leading to the salinosporamides proceeding via optically active β-keto secondary amides, are able to maintain the stereochemical integrity at the labile C2 stereocenter or if a dynamic kinetic resolution is operative.
Preparative UV-VIS Laser Photochemistry: Photocycloadditions of Methylenelactones with Benzophenone and p-Benzoquinone. Oxygen Trapping of Paterno-Buechi Triplet 1,4-Diradicals as Model Reactions for Quinghaosu-Type 1,2,4-Trioxanes
Adam, Waldemar,Kliem, Ulrike,Lucchini, Vittorio
, p. 869 - 876 (2007/10/02)
The UV-VIS laser irradiation of 4-penten-4-olide (1) with benzophenone (BP) or with p-benzoquinone (BQ) under an argon atmosphere afforded the acetal-type oxetanes 2-BP and 2-BQ, respectively.Only for BP was the oxetane regioisomer 3-BP obtained, actually as major product, while 3-BQ appears to be photolabile under VIS-laser photolysis conditions and thus does not accumulate in sufficient amounts for detection.Under an oxygen atmosphere, besides these oxetane products also the 1,2,4-trioxanes 5-BP and 5-BQ, the oxygen trapping products of the intermediary preoxetanetriplet diradicals 12, were isolated and fully characterized.These results demonstrate that spirolactone-type 1,2,4-trioxanes as quinghaosu analogues are accessible via trapping of Paterno-Buechi triplet 1,4-diradicals by molecular oxygen.In the case of diketene as enol-lactone partner, the Paterno-Buechi reaction with BQ gave a complex product mixture even under an argon atmosphere, leading to the oxetane 6 as major product, and the spirocyclobutanone 7 and spirobioxetane 8 as minor products.Under an oxygen atmosphere also the spiroacetal 9 was obtained, but no trioxanes (oxygen trapping) could be detected in this VIS-laser photolysis.
Preparation and properties of metallacyclobutanes of nickel and palladium
Miyashita, Akira,Ohyoshi, Mayumi,Shitara, Hiroaki,Nohira, Hiroyuki
, p. 103 - 112 (2007/10/02)
Bis(phosphine)-3,3-dimethylnickela- and palladacyclobutanes have been prepared by intramolecular C-H insertion reaction of the corresponding dineopentyl metal complexes.Nickelacyclobutane complexes decompose when heated thereby undergoing competitive carb
MECHANISM OF ACETOACETYLATION OF SUBSTITUED ANILINES
Knizek, Jiri,Lejdar, Erhard,Vetesnik, Pavel
, p. 365 - 374 (2007/10/02)
Kinetics have been studied of the reaction of diketene with substituted anilines, and the reaction rate has been found to depend on relative permitivity of the system.The rate and equilibrium constants have been calculated by combination of rate and equilibrium relations with the relation by Amis; the constants correlate with the Hammett substituent constants.The reaction does not proceed as a simple bimolecular process.A reaction mechanism has been suggested.
Catalytic Dimerization of Ketene. A Simple and Convenient Method for the Preparation of Diketene and Esters of Acetoacetic Acid
Jarowicki, Krzysztof,Kwitakowski, Stefan
, p. 141 - 144 (2007/10/02)
A new method for the preparation of diketene is described.The main feature of the procedure is the dimerization of ketene in the presence of tetramethylethylenediamine (TMEDA) and the direct use of crude diketene in the syntheses of acetoacetic esters.Keywords: Dimerization of ketene; Tetramethylethylenediamine, catalytic action of
