First diastereoselective synthesis of methyl caffeoyl- and feruloyl-muco-quinates

Abstract

We report on a diastereoselective synthesis of six derivatives of caffeoyl- and feruloyl-muco-quinic acids. All the muco-quinic acid derivatives were obtained in excellent yield in five steps starting from quinic acid, caffeic acid and ferulic acid. Allyl ether protection of trans-hydroxy cinnamic acids was here introduced to chlorogenic acids synthesis. We show that muco-quinic acid derivatives, which are formally diastereoisomers of chlorogenic acids, can be readily distinguished by their tandem mass spectra.

What is under the hump? Mass spectrometry based analysis of complex mixtures in processed food – lessons from the characterisation of black tea thearubigins, coffee melanoidines and caramel

“…19). [36][37][38][39][40] Additionally we could recently demonstrate that in the coffee brewing process water addition to the cinnamoyl olenic moiety in 19 followed by belimination yields rstly b-hydroxy-esters and subsequently cis-CGA derivatives 20 (see Fig. 19).…”

Mass Spectrometric Investigation of the Chemical Composition of Caramel Formed upon Heating of Disaccharides

“…For galactose, a dehydration process leading to a galactose based ion at m/z 161.1 is favoured (see later for detailed discussion). Epimerization was shown to be not observed for monomeric hexoses previously [23], as it has been reported in quinic acid and chlorogenic acid chemistry in food processing chemistry at identical temperatures [32,33].…”

An Unambiguous Nomenclature for the Acyl-quinic Acids Commonly Known as Chlorogenic Acids

“…16,19,20 There are reports arising from distinctive retention time and LC−MS n fragmentation data that acyl derivatives of a quinic acid isomer, as yet incompletely characterized, occur in several species. 21−23 Roasted coffee beans contain a 3-caffeoyl-muco-quinic acid and a 3-feruloyl-mucoquinic acid, 24,25 along with free muco-quinic, free scyllo-quinic, and free (±)-epi-quinic acid, 26 all of which have been confirmed by synthesis.…”

“…1 l -(−)-Quinic acid 1 is the only isomer commercially available (although frequently described in catalogs as d -quinic acid rather than l -quinic acid) and generally assumed to be the isomer present in the majority of reported acyl-quinic acids, but only rarely has this been proven. − At least one acyl-(±)- epi -quinic acid has been reported (originally as isoquinic acid) and the quinic acid moiety released by saponification shown to be distinct from 1 l -(−)-quinic acid. ,, There are reports arising from distinctive retention time and LC–MS n fragmentation data that acyl derivatives of a quinic acid isomer, as yet incompletely characterized, occur in several species. − Roasted coffee beans contain a 3-caffeoyl- muco -quinic acid and a 3-feruloyl- muco -quinic acid, , along with free muco -quinic, free scyllo -quinic, and free (±)- epi -quinic acid, all of which have been confirmed by synthesis.…”