[reaction: see text] A practically simple three-component chiral derivatizing protocol for determining the enantiopurity of 13 chiral primary amines by (1)H NMR spectroscopic analysis is described, including analysis of those that contain remote stereocenters.
[reaction: see text] A practically simple three-component chiral derivatization protocol for determining the enantiopurity of chiral 1,2-, 1,3-, and 1,4-diols by (1)H NMR spectroscopic analysis is described. The method involves treatment with 2-formylphenylboronic acid and enantiopure alpha-methylbenzylamine to afford a mixture of diastereoisomeric iminoboronate esters whose ratio is an accurate reflection of the enantiopurity of the parent diol.
Poly(2-oxazoline)-based networks currently receive great interest due to their versatile properties that can be tailor made by desktop-planned modifications. This feature summarizes strategies for the preparation of these networks, comprising the in situ cross-linking as well as polymer-analogous cross-linking routines such as (reversible) complex formation, physical processes, and covalent bond formation (involving reactions with olefinic species as well as with epoxides, isocyanates, aldehydes, acids, and their derivatives). Reflecting prominent application examples in the biomedic(in)al sector, poly(2-oxazoline)-co-polyester networks are described in a dedicated section.
A three-component chiral derivatization protocol for determining the enantiopurity of chiral diols by (1)H NMR spectroscopic analysis is described here. The present approach involves the derivatization of 1,2- 1,3- and 1,4-diols with 2-formylphenylboronic acid and enantiopure alpha-methylbenzylamine. This method affords a mixture of diastereoisomeric iminoboronate esters whose ratio can be determined by integration of well-resolved diastereotopic resonances in their (1)H NMR spectra, thus enabling the determination of the enantiopurity of the parent diol. The protocol as described takes less than 90 min to complete.
A 32-membered library of poly(2-oxazoline)-based hydrogels of the composition pEtOx(m) -pPhOx(n) -pPBO(q) (m/n = 150/0, 100/50, 50/100, and 0/150; q = 1.5-30) was prepared from 2-ethyl- (EtOx), 2-phenyl-2-oxazoline (PhOx), and phenylene-1,3-bis-(2-oxazoline) (PBO). The polymerizations were performed from ground monomer mixtures at 140 °C in a single-mode microwave reactor in reaction times as short as 1 h. Purified hydrogels, containing no residual monomers, were obtained in yields of 95% or higher. Acid-mediated hydrolysis rates as well as swelling degrees of the hydrogels were adjustable over a broad range; swelling degrees in water/ethanol/dichloromethane ranged from 0 to 13.8/11.7/20.0. The hydrogels could incorporate organic molecules according to in situ or post-synthetic routines. Post-synthetic routines enabled for the preparation of hydrogels from which the incorporated compounds were only released through diffusion processes if the solvent was changed or through hydrogel degradation if the pH was lowered.
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