3553-78-4Relevant academic research and scientific papers
Novel protocol for the synthesis of organic ammonium tribromides and investigation of 1,1′-(Ethane-1,2-diyl)dipiperidinium bis(tribromide) in the silylation of alcohols and thiols
Dey, Rupa R.,Paul, Bappi,Dhar, Siddhartha S.,Bhattacharjee, Sushmita
supporting information, p. 1545 - 1547 (2015/02/19)
A novel and efficient protocol for the synthesis of organic ammonium tribromides (OATBs) is developed by using inexpensive and eco-friendly periodic acid as an oxidant for the conversion of Br-to Br3-. The method does not use any mineral acid and metal oxidants. The protocol is utilized to synthesize a new bis(tribromide) viz., 1,1′-(ethane-1,2-diyl)dipiperidinium bis(tribromide) (EDPBT). EDPBT is investigated as a catalyst in the silylation of alcohols and thiols by HMDS (hexamethyldisilazane) under solvent-free conditions.
Synthesis and characterization of 2-carboxyethyltriphenyl phosphonium tribromide and its application as catalyst in silylation of alcohols and thiols under solvent-free condition
Dey, Rupa Rani,Dhar, Siddhartha Sankar
supporting information, p. 2355 - 2363 (2014/07/22)
A phosphonium-based catalyst, 2-carboxyethyltriphenyl phosphonium tribromide (CTPTB), has been synthesized by reacting triphenyl phosphine with acrylic acid and potassium bromide under solvent-free condition followed by oxidation of Br- to with KMnO4. This hitherto unknown tribromide reagent is characterized by ultraviolet-visible, Fourier transform-infrared, 1H NMR, and 31P NMR spectroscopy. Its efficacy as catalyst is established by investigating its catalytic activity in silylation of alcohols and thiols by hexamethyl disilazane (HMDS). It is found to be a very good catalyst and selectively and efficiently catalyzes the silylation reactions. Copyright
Unsuccessful attempts to add alcohols to transient 2-amino-2-siloxy- silenes-leading to a new benign route for base-free alcohol protection
Guliashvili, Tamaz,Tibbelin, Julius,Ryu, Jiyeon,Ottosson, Henrik
supporting information; experimental part, p. 9379 - 9385 (2011/01/07)
Thermolytic formation of transient 1,1-bis(trimethylsilyl)-2-dimethylamino- 2-trimethylsiloxysilene (2) from N,N-dimethyl(tris(trimethylsilyl)silyl) methaneamide (1) in presence of a series of alcohols was investigated. The products are, however, not the expected alcohol-silene addition adducts but silylethers formed in nearly quantitative yields. Thermolysis of 1 in the presence of both alcohols (MeOH or iPrOH) and 1,3-dienes (1,3-butadiene or 2,3-dimethyl-1,3-butadiene) gives alkyl-tris(trimethylsilyl)silylethers and the [4+2] cycloadducts between the silene and diene, which confirms the presence of 2 and that it is unreactive towards alcohols. The observed silylethers are substitution adducts where the amide group of the silylamide is replaced by an alkoxy group, and the reaction time is reflected in the steric bulk of the alcohol. Indeed, the formation of silylethers from the reaction of alcohols with silylamide represents a new base-free method for protection of alcohols. The protection reactions using 1 progresses at elevated temperatures, or alternatively, under acid catalysis at ambient temperature, and similar protections can be carried out with N-cyclohexyl(triphenylsilyl)methaneamide and N,N-dimethyl(trimethylsilyl)methaneamide. The latter silylamide can be used under neutral conditions at room temperature. The only by-products are formamides (N,N-dimethylformamide (DMF) or N-cyclohexylformamide), and the reactions can be performed without solvent. In addition to alcohols we also examined the method for protection of diols, thiols and carboxylic acids, and also these reactions proceeded in high yields and with good selectivities. The Royal Society of Chemistry.
Efficient Preparation of a Key Intermediate in the Synthesis of Roxifiban by Enzymatic Dynamic Kinetic Resolution on Large Scale
Pesti, Jaan A.,Yin, Jinguao,Zhang, Lin-Hua,Anzalone, Luigi,Waltermire, Robert E.,Ma, Philip,Gorko, Edward,Confalone, Pat N.,Fortunak, Joseph,Silverman, Charlotte,Blackwell, John,Chung,Hrytsak, Michael D.,Cooke, Mary,Powell, Lakisha,Ray, Charles
, p. 22 - 27 (2013/09/04)
Additional information is presented for the transformation of a kinetic resolution into a dynamic kinetic resolution of the isobutyl ester 5b to form the acid 2 in high yield and ee via the intermediacy of a thioester 6c, (Pesti, J. A.; Yin, J.; Zhang, L.-H; Anzalone, L. J. Am. Chem. Soc. 2001, 123, 11075-11076.). The development of optimized reaction conditions for the preparation of 6c, its dynamic kinetic resolution to 2, and the scale-up of both reactions into a pilot plant are described.
Properties and reactions of substituted 1,2-thiazetidine 1,1-dioxides: Reactions of 3-acetoxy-β-sultams with sulfur nucleophiles
Merkle,Otto
, p. 657 - 660 (2007/10/02)
The acetate moiety of 3-acetoxy-β-sultams 2 is easily displaced by sulfur nucleophiles yielding the alkylthio-β-sultams 3 which are transformed into stable derivatives 4 by silylation. The synthesis of the cephem analogue 7 is described. Reactions of 2 wi
