Electrogenerated Superoxide-Activated Carbon Dioxide. A New Mild and Safe Approach to Organic Carbamates
摘要:
The electrochemical reduction of O-2 (E = -1.0 V vs SCE) in dipolar aprotic solvents in the presence of CO2 gave a carboxylating reagent (O-2(.-)/CO2) able to convert amines and different types of their derivatives into carbamates. Primary and secondary aliphatic and aromatic amines were converted into the corresponding ethyl carbamates by the addition of EtI to the carbamate anions generated in the first step of the reactions. The yields were dependent on the nucleophilicity of the nitrogen atom. beta-Bromoethyl- and propylamine gave 2-oxazolidinone and tetrahydro-1,3-oxazin-2-one in moderate yields. N-Acyl or N-(alkoxycarbonyl)alkylamines bearing a leaving group at the beta position of the alkyl substituent were converted into 3-substituted-2-oxazolidinones in high yields. By using chiral substrates, enantiopure 3-alkoxycarbonyl(or acyl)-4-substituted oxazolidin-2-ones (70-85% isolated yields) were obtained. This represents a new mild and safe route to these important auxiliaries for asymmetric synthesis. Some limitations of the process are also evidenced and accounted for.
Asymmetric Hydroformylation of <i>Z</i>-Enamides and Enol Esters with Rhodium-Bisdiazaphos Catalysts
作者:M. Leigh Abrams、Floriana Foarta、Clark R. Landis
DOI:10.1021/ja507701k
日期:2014.10.15
Asymmetric hydroformylation (AHF) of Z-enamides and Z-enol esters provides chiral, alpha-functionalized aldehydes with high selectivity and atom economy. Rh-bisdiazaphospholane catalysts enable hydroformylation of these challenging disubstituted substrates under mild reaction conditions and low catalyst loadings. The synthesis of a protected analog of l-DOPA demonstrates the utility of AHF for enantioselective
[EN] METHOD OF CONVERTING ALCOHOL TO HALIDE<br/>[FR] PROCÉDÉ DE CONVERSION D'UN ALCOOL EN HALOGÉNURE
申请人:UNIV SAARLAND
公开号:WO2016202894A1
公开(公告)日:2016-12-22
The present invention relates to a method of converting an alcohol into a corresponding halide. This method comprises reacting the alcohol with an optionally substituted aromatic carboxylic acid halide in presence of an N-substituted formamide to replace a hydroxyl group of the alcohol by a halogen atom. The present invention also relates to a method of converting an alcohol into a corresponding substitution product. The second method comprises: (a) performing the method of the invention of converting an alcohol into the corresponding halide; and (b) reacting the corresponding halide with a nucleophile to convert the halide into the nucleophilic substitution product.
The three-component Petasis borono-Mannich reaction starting with easily accessible N-protected α-amino aldehydes produces efficiently and diastereoselectively 1,2-trans-diamines with an enantiomeric excess of up to 98%.
Lewis Base Catalysis Enables the Activation of Alcohols by means of Chloroformates as Phosgene Substitutes
作者:Ben Zoller、Tanja Stach、Peter H. Huy
DOI:10.1002/cctc.202001175
日期:2020.11.19
thermodynamic driving force and lower kinetic barriers. However, the cheapest acid chloride phosgene (COCl2) is a highly toxic gas. Against this background, phenyl chloroformate (PCF) was discovered as inherently safer phosgene substitute for the SN‐type formation of C−Cl and C−Br bonds using alcohols. Thereby, application of the Lewis bases 1‐formylpyrroldine (FPyr) and diethylcyclopropenone (DEC) as catalysts
Discovery of a Novel Series of Biphenyl Benzoic Acid Derivatives as Highly Potent and Selective Human β3 Adrenergic Receptor Agonists with Good Oral Bioavailability. Part II
central part of our first generation biphenyl (FGB) series was modified to improve in vitro and in vivo beta3-AR potency without loss of oral bioavailability. First, in this study, we focused our efforts on replacement of the 3-chlorophenyl moiety in the LHS of FGB analogues with 3-pyridyl ring analogues to adjust the lipophilicity. Second, we investigated the replacement of the central part of this