Molar equivalents of synthetic (2R,3S,4R or S)-leucocyanidin and (+)-catechin condense with exceptional rapidity at pH 5 under ambient conditions to give the all-trans-[4,8]- and [4,6]-bi-[(+)-catechins] (procyanidins B3, B6) the all-trans-[4,8:4,8]- and [4,8:4,6]-tri-[(+)-catechins] (procyanidin C2 and isomer).[7]
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^Quinde-Axtell, Zory; Baik, Byung-Kee (2006). "Phenolic Compounds of Barley Grain and Their Implication in Food Product Discoloration". Journal of Agricultural and Food Chemistry. 54 (26): 9978–84. doi:10.1021/jf060974w. PMID17177530.
^Benavides, Angelyne; Montoro, Paola; Bassarello, Carla; Piacente, Sonia; Pizza, Cosimo (2006). "Catechin derivatives in Jatropha macrantha stems: Characterisation and LC/ESI/MS/MS quali–quantitative analysis". Journal of Pharmaceutical and Biomedical Analysis. 40 (3): 639–47. doi:10.1016/j.jpba.2005.10.004. PMID16300918.
^Delcour, Jan. A.; Ferreira, Daneel; Roux, David G. (1983). "Synthesis of condensed tannins. Part 9. The condensation sequence of leucocyanidin with (+)-catechin and with the resultant procyanidins". Journal of the Chemical Society, Perkin Transactions 1: 1711. doi:10.1039/P19830001711.