Peroxyoxalate chemiluminescence detection for the highly sensitive determination of fluorescence-labeled chlorpheniramine with Suzuki coupling reaction.

A sensitive and selective high performance liquid chromatography-peroxyoxalate chemiluminescence (PO-CL) method has been developed for the simultaneous determination of chlorpheniramine (CPA) and monodesmethyl chlorpheniramine (MDCPA) in human serum. The method combines fluorescent labeling with 4-(4,5-diphenyl-1H-imidazole-2-yl)phenyl boronic acid using Suzuki coupling reaction with PO-CL detection. CPA and MDCPA were extracted from human serum by liquid-liquid extraction with n-hexane. Excess labeling reagent, which interfered with trace level determination of analytes, was removed by solid-phase extraction using a C18 cartridge. Separation of derivatives of both analytes was achieved isocratically on a silica column with a mixture of acetonitrile and 60 mM imidazole-HNO(3) buffer (pH 7.2; 85:15, v/v) containing 0.015% triethylamine. The proposed method exhibited a good linearity with a correlation coefficient of 0.999 for CPA and MDCPA within the concentration range of 0.5-100 ng/mL. The limits of detection (S/N = 3) were 0.14 and 0.16 ng/mL for CPA and MDCPA, respectively. Using the proposed method, CPA could be selectively determined in human serum after oral administration

Olefin cross-metathesis-based approaches to furans: procedures for the preparation of di- and trisubstituted variants.

Olefin cross-metathesis (CM)-based protocols enable short, flexible and regiocontrolled access to substituted furan derivatives. Specifically, CM of allylic alcohol and enone components provides γ-hydroxyenone intermediates that are cycloaromatized to the final furan derivatives on exposure to either acid or a discrete Heck arylation step. This latter process concomitantly introduces an extra substituent onto the furan target with complete control of regiochemistry. The methodology described here serves as the basis for developing other CM-based entries to diverse heteroaromatic compounds. This protocol describes in detail the following stages of the furan procedures: (i) the tandem formation and acid-catalyzed cyclization of the γ-hydroxyenone to afford a 2,5-disubstituted furan directly; (ii) CM of an allylic alcohol with an enone to provide an isolated γ-hydroxyenone; and (iii) Heck arylation of this γ-hydroxyenone to afford a 2,3,5-trisubstituted furan. The reaction procedure given for the formation of the 2,5-disubstituted furan (option A) takes ∼26.5 h to complete. The procedure described for the formation of the 2,3,5-trisubstituted furan (option B) takes ∼52.5 h