Mariano García

Chemoenzymatic synthesis of pure enantiomeric 2-aryl propionic acids

Abstract A new chemoenzymatic procedure to obtain pure enantiomeric 2-arylpropionic acids is described. The one pot synthesis of (±)-2-arylpropionic acids is carried out by addition of dichlorocarbene to the O bond of arylmethylketones and hydrogenolysis of the addition product. The racemic mixture is resolved by enantiospecific hydrolysis of the racemic ethyl esters using native lipase from Candida rugosa . The good yields, the accessibility of the starting arylmethylketones and the stereospecificity of the enzymatic hydrolysis make the process interesting in order to obtain the same non steroidal antiinflammatory drugs such as Ibuprofen or Naproxen.

Indoor positioning using nonparametric belief propagation based on spanning trees

Nonparametric belief propagation (NBP) is one of the best-known methods for cooperative localization in sensor networks. It is capable of providing information about location estimation with appropriate uncertainty and to accommodate non-Gaussian distance measurement errors. However, the accuracy of NBP is questionable in loopy networks. Therefore, in this paper, we propose a novel approach, NBP based on spanning trees (NBP-ST) created by breadth first search (BFS) method. In addition, we propose a reliable indoor model based on obtained measurements in our lab. According to our simulation results, NBP-ST performs better than NBP in terms of accuracy and communication cost in the networks with high connectivity (i.e., highly loopy networks). Furthermore, the computational and communication costs are nearly constant with respect to the transmission radius. However, the drawbacks of proposed method are a little bit higher computational cost and poor performance in low-connected networks.

Synthesis of α,α-disubstituted acetic acids using low-valent titanium

Dihalogenocarbenes generated using low-valent titanium (LVT) undergo a one-pot cycloaddition to diaryl, aryl alkyl or dialkyl ketones to give α,α-disubstituted acetic acids such as (R,S)-2-arylpropanoic acids. TiI4 proved most effective in this reaction for which the product yield was optimized by use of an excess of reducing agent.

An Experimental Study of RSS-Based Indoor Localization Using Nonparametric Belief Propagation Based on Spanning Trees

Nonparametric belief propagation (NBP) is the well-known method for cooperative localization in wireless sensor networks. It is capable to provide information about location estimation with appropriate uncertainty and to accommodate non-Gaussian distance measurement errors. However, the accuracy of NBP is questionable in loopy networks. Therefore, in this paper, we propose a novel approach, NBP based on spanning trees (NBP-ST) created by breadth first search (BFS) method. In addition, we propose a reliable indoor model based on obtained received-signal-strength (RSS) measurements in our lab. According to our experimental results, NBP-ST performs better than NBP in terms of accuracy and communication cost in the networks with high connectivity (i.e., highly loopy networks).

Hydrolysis of 2-substituted aryl and heteroaryl alkanoates by Candida rugosalipase

AbstractsThe hydrolysis of several esters catalyzed by lipase of Candida rugosa was used to analyse the interaction between the ester substrate and the active site and the geometry and steric restrictions of ‘alk‘, ‘ar‘ and ‘h‘ subsites. Using 4-R-C H -CH(R‘)-COOEt and ethyl trans-cinnamate, the presence of a low electronic density zone in the ‘ar‘ pocket is described, the dimensions of the pocket produced by Phe-296 and Leu-297 in the ‘alk‘ subsite and the size of the ‘h‘ subsite are described.

A new method for the preparation of 2-aryl propionic acids using low-valent titanium

Abstract The addition of dihalocarbenes to arylmethylketones in the presence of low-valent titanium yields 2-aryl propionic acids in acceptable yield by one pot reaction. The reaction conditions were optimized. The TiCl 4 /LiAlH 4 ratio is one variable that controls the selectivity of the process.

Enantiospecific hydrolysis of esters of nonsteroidal antiinflammatory drugs using lipase of Candida cylindracea

Abstract Enantiospecific hydrolysis of esters of 2-arylpropionic acids with antiinflammatory activity has been carried out. The racemic acids were synthetized by Willgerodt—Kindler synthesis in good yields. The enzymatic hydrolysis of the esters was carried out in a batch reactor with 0.2 M substrate concentration.