144397-85-3Relevant academic research and scientific papers
Enantioselective cyanation/brook rearrangement/C-acylation reactions of acylsilanes catalyzed by chiral metal alkoxides
Nicewicz, David A.,Yates, Christopher M.,Johnson, Jeffrey S.
, p. 6548 - 6555 (2007/10/03)
New catalytic enantioselective cyanation/1,2-Brook rearrangement/C- acylation reactions of acylsilanes (4) with cyanoformate esters (7) are described. The products of the reaction are fully substituted malonic acid derivatives (8). Catalysts for this transformation were discovered via a directed candidate screen of 96 metal-ligand complexes. Optimization of a (salen)aluminum complex revealed significant remote electronic effects and concentration effects. The scope of the reaction was investigated by using a number of aryl acylsilanes and cyanoformate esters. Chemoselective reduction of the reaction products (8) afforded new enantioenriched α-hydroxy-α- aryl-β-amino acid derivatives (32-34) and β-lactams (35 and 36). This reaction provides a simple method for the construction of new nitrogen-containing enantioenriched chiral building blocks.
Catalytic asymmetric acylation of (silyloxy)nitrile anions
Nicewicz, David A.,Yates, Christopher M.,Johnson, Jeffrey S.
, p. 2652 - 2655 (2007/10/03)
An enantiopure (salen)aluminum alkoxide complex catalyzes the asymmetric coupling of acylsilanes and cyanoformate esters [Eq. (1), R = Bn, Et]. The reactions afford unsymmetrical, fully protected malonic acid derivatives that may be elaborated to nonnatural β-amino acid derivatives, and represent the first asymmetric catalytic reactions involving protected cyanohydrin anions.
Synthesis of carbonates and related compounds from carbon dioxide via methanesulfonyl carbonates
Bratt, Mark O.,Taylor, Paul C.
, p. 5439 - 5444 (2007/10/03)
Carbonate anions resulting from reaction of primary or secondary alcohols with carbon dioxide, when added to methanesulfonic anhydride in cooled acetonitrile solution, yield methanesulfonyl carbonates, a new class of synthetic intermediate. Base-mediated reaction of the methanesulfonyl carbonates with alcohols, thiols, and amines yields carbonates, thiocarbonates, and carbamates, respectively. Overall yields for the three steps vary from 19% to 42%.
Synthesis of mixed carbonates via a three-component coupling of alcohols, CO2, and alkyl halides in the presence of K2CO3 and tetrabutylammonium iodide
Shi, Min,Shen, Yu-Mei
, p. 386 - 393 (2007/10/03)
Various mixed carbonates can be conveniently prepared in good yields using the corresponding alcohols, alkyl halides under CO2 atmosphere in the presence of potassium carbonate or sodium carbonate and tetrabutylammonium iodide.
Transfer of Alkoxycarbonyl from Alkyl Imidazolium-2-carboxylates to Benzyl Alcohol, a Cyclohexanone Enamine and Diethylamine
Bakhtiar, Cuross,Smith, Edward H.
, p. 239 - 244 (2007/10/02)
Alkylimidazole-2-carboxylates may be alkylated with methyl triflate to give the corresponding N-methylimidazolium salts.These salts react with benzyl alcohol in the presence of 1,4-diazabicyclooctane, with 1-(pyrrolidin-1-yl)cyclohexene and with diethylamine to give benzyl alkyl carbonates, an enamino ester and a urethane respectively; in one case a tetrahedral intermediate is observed.The corresponding phenyl ester was consumed without attack by benzyl alcohol at the carbonyl group.A 2-cyanoimidazolium salt underwent similar ill-defined consumption whereas a 2-dimethylaminocarbonyl derivative remained unchanged. 2-Methylsulfonylimidazolium salts suffered attack by benzyl alcohol at the ring C-2.
Preparation of urethane and carbonate products
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, (2008/06/13)
The present invention provides a process for preparing urethanes and carbonates from an amine or an alcohol, carbon dioxide and a hydrocarbyl halide. The amine or alcohol is reacted with carbon dioxide in a suitable solvent system and in the presence of an amidine or guanidine base, to form the ammonium carbamate or carbonate salt which is then reacted in a polar aprotic solvent with a hydrocarbyl halide. Polymer products can also be prepared utilizing this process or utilizing the resulting urethanes and carbonates under standard polymerization conditions.
Vinyl carbonates as novel alkoxycarbonylation reagents in enzymatic synthesis of carbonates
Pozo,Pulido,Gotor
, p. 6477 - 6484 (2007/10/02)
Carbonates could be obtained by enzymatic alkoxycarbonylation from vinyl carbonates, which are easily prepared from vinyl chloroformate. The reaction was catalyzed by Candida antarctica lipases, SP 435 and SP 435 A. The method could be also used for the synthesis of carbamates. When racemic alcohols were used, lipase catalyzed their resolution, and chiral carbonates were obtained with different enantiomeric excesses depending upon the structure of the alcohol.
