Clean, High-yield Preparation Of S,S- and R,S- Amino Acid Isosteres

The present invention provides compounds and methods that can be used to convert the intermediate halomethyl ketones (HMKs), e.g., chloromethyl ketones, to the corresponding S,S- and R,S-diastereomers. More particularly, the present invention provides: (1) reduction methods; (2) inversion methods; and (3) methods involving the epoxidation of alkenes. Using the various methods of the present invention, the R,S-epoxide and the intermediary compounds can be prepared reliably, in high yields and in high purity

Preparation of 2S,3S-N-Isobutyl-N-(2-hydroxy-3-amino-4-phenylbutyl)-p-nitrobenzenesulfonylamide hydrochloride and other derivatives of 2-hydroxy-1,3-diamines

The present invention provides a new process for the preparation of 2S,3S-N-isobutyl-N-(2-hydroxy-3-amino-4phenylbutyl)- p-nitrobenzenesulfonylamide hydrochloride, wherein this compound is prepared directly from the chloromethylalcohol. Importantly, the process of the present invention results in higher yields of 2S,3S-N-isobutyl-N-(2hydroxy -3 -amino -4-phenylbutyl) -pnitrobenzenesulfonylamide hydrochloride without sacrificing its purity. The processes of the present inventin can be used to prepare not only the 2S,3S-derivative, but also the 2R,3S-, 2S,2R- and the 2R,3R-derivatives

Preparation of 2S,3S-N-Isobutyl-N-(2-hydroxy-3-amino-4-phenylbutyl)-p-nitrobenzenesulfonylamide hydrochloride and other derivatives of 2-hydroxy-1,3-diamines

The present invention provides a new process for the preparation of 2S,3S-N-isobutyl-N-(2-hydroxy-3-amino-4phenylbutyl)- p-nitrobenzenesulfonylamide hydrochloride, wherein this compound is prepared directly from the chloromethylalcohol. Importantly, the process of the present invention results in higher yields of 2S,3S-N-isobutyl-N-(2hydroxy -3 -amino -4-phenylbutyl) -pnitrobenzenesulfonylamide hydrochloride without sacrificing its purity. The processes of the present invention can be used to prepare not only the 2S,3S-derivative, but also the 2R,3S-, 2S,2R- and the 2R,3R-derivatives

A Facile Synthesis of (\u3cem\u3etert\u3c/em\u3e-alkoxy)amines

Tertiary alcohols react with stoichiometric BF3·Et2O and N-hydroxyphthalimide to yield N-alkoxyphthalimides. Subsequent hydrazinolyses afford the title compounds

Removal of Benzaldehyde from Methanol Using Alkoxyamine Functionalized Silica Gel

Alkoxyamines (RONH2) react readily with aldehydes and ketones to form stable oxime ethers, and, thus are expected to be excellent scavengers of these compounds. We installed alkoxyamines on silica gel surface to remove benzaldehyde from methanol. Silica gel was immersed in H2O2/H2SO4 solution to activate the surface. Activated silica gel was then reacted with 3-chloropropyltrichlorosilane. Displacement of the chloride with N-hydroxyphthalimide and subsequent treatment with hydrazine provided alkoxyamines on the surface of silica gel. The resulting silica gel surface with alkoxyamine functional groups was immersed in a 100 ppm benzaldehyde solution in methanol. After 24 h, the results showed 86.5 + 7.2 % removal of benzaldehyde from methanol

Alkoxyamine Polymers: Versatile Materials for Surface Ligation Applications

Immobilization of biomolecules (i.e., proteins, carbohydrates), on polymeric surfaces has been an area of intense research. The resultant bioconjugates often display increased stability, bioavailability and activity. Our research program seeks to explore the utility of the alkoxyamine (RONH2) functional group in new materials as versatile ligating sites for the immobilization of various compounds. The ease with which alkoxyamines (RONH2) condense with aldehydes or ketones has prompted their widespread use in labelling liposome, bacterial and mammalian cell surfaces as well as chemoselectively ligating small molecule ‘recognition elements\u27 onto polyfunctional substrates. These condensation reactions proceed in aqueous media to afford the robust oxime ethers in near quantitative yields, making these conjugations ideal for a variety of applications. Thus, alkoxyamines are excellent ‘molecular anchors\u27 to immobilize aldehyde/ketone compounds on a surface. We have installed alkoxyamines on polymer surfaces to tether a variety of compounds through the covalent oxime ether bond to the polymer backbone. Our synthetic efforts towards these novel alkoxyamine polymers as well as initial aldehyde/ketone immobilization studies will be discussed

The Effects of a Networked Data Acquisition System on Student Learning in General Chemistry Laboratories

We have recently incorporated a networked data acquisition and analysis system into in our second semester general chemistry laboratories. Our investigation team has conducted a study to evaluate the effects of the networked data acquisition system on student performance on a Beer\u27s Law laboratory. We focused on two specific phenomena: the effect of the networked data acquisition system on 1) student learning of specific content material and 2) student comfort level with laboratory work and data analysis. The study involved a networked data acquisition group (employing a UV-Vis spectrometer and colorimeters) and a control group (employing traditional, single wavelength spectrometers). Pre- and post-assessments were performed using written surveys, one-on-one student interviews, and lab practical tasks. Results from the study indicating changes in student baseline knowledge relating to Beer\u27s Law and student comfort level in performing measurements and analysis will be presented

The Effects of PC-Based Laboratories on Student Learning

The Department of Chemistry at Western Kentucky University recently incorporated a net-worked MeasureNet data acquisition and analysis system into in the second semester General Chemistry laboratories. Our investigation team has conducted a study to evaluate the effects of the MeasureNet system on student learning and performance on a Beer\u27s Law laboratory. We focused on two phenomena: the effect of the MeasureNet system on 1) student learning of specific content material and 2) student interest in chemistry and science in general. The study involved a MeasureNet system group (employing a UV-Vis spectrometer and colorimeters) and a control group (employing traditional Spectronic 20D instruments). Pre- and post-assessments were performed using written surveys, one-on-one student interviews and lab practical tasks. Results from the study indicating changes in student baseline knowledge relating to Beer\u27s Law and student comfort level in performing measurements and analysis will be presented

Progress Toward Cariporide Analogs for Sodium-Proton Exchange Inhibition

The sodium proton exchanger (NHE) is particularly important in maintaining the intracellular pH in human heart and brain. Under anaerobic conditions (i.e., ischemia), a shift from oxidative to nonoxidative glycolysis occurs. The resultant decrease in the intracellular pH activates NHE, which increases the intracellular sodium, initiating the sequence of physiological events that lead to cell death. Thus, there has been great interest in the development of compounds that inhibit NHE. Indeed, potent NHE inhibitors are available. However, a fundamental impediment to the field is the delivery of these compounds to poorly vascularized tissues during the early phases of ischemia when NHE inhibition is most beneficial. We have synthesized analogs of cariporide, a potent (e.g., nanomolar IC50 activity) NHE inhibitor, to address these temporal and delivery challenges. The preparation and biological activities of our cariporide analogs will be discussed