114569-31-2Relevant academic research and scientific papers
Syntheses of doubly linked proanthocyanidins using free flavan units as nucleophiles: Insight into the origin of the high regioselectivity of annulation
Betkekar, Vipul V.,Harachi, Mio,Suzuki, Keisuke,Ohmori, Ken
supporting information, p. 9129 - 9134 (2019/11/05)
A synthesis method of doubly linked flavan dimers is reported via the acid-promoted annulation reaction using nascent catechins, (+)-catechin or (-)-epicatechin, as a dianionic partner and an ethylenedioxy-bridged flavan as a dicationic partner. Procyanidins A1 and A2 were synthesized. On the high regioselectivity of the annulation reactions, model experiments and computational studies were carried out.
Tannins and Related Compounds. LIX. Aesculitannins, Novel Proanthocyanidins with Doubly-Bonded Structures from Aesculus hippocastanum L.
Morimoto, Satoshi,Nonaka, Gen-ichiro,Nishioka, Itsuo
, p. 4717 - 4729 (2007/10/02)
A chemical examination of the seed shells of Aesculus hyppocastanum L.has led to the isolation of proanthocyanidins A-6 (10) and A-7 (11), and aesculitannins A (12), B (13), C (14), D (15), E (16), F (17) and G (18).On the basis of chemical and spectroscopic evidence, proanthocyanidins A-6 (10) and A-7 (11) have been determined to be A-type dimers each possessing a C-4, C-6 interflavanoid linkage, while aesculitannins A (12), B (13), C (14), D (15), E (16), F (17) and G (18) have been characterized as oligomeric proanthocyanidins possessing A-type unit(s) in each molecule.In addition, the presence of (-)-epicatechin (1), proanthocyanidins B-5 (3), A-2 (4), A-4 (5) and C-1 (6), epicatechin-(4β->6)-epicatechin-(4β->6)-epicatechin (7), and cinnamtannins B1 (8) and B2 (9) was also demonstrated Keywords---Aesculus hippocastanum; Hippocastanaceae; aesculitannin; doubly-bonded proanthocyanidin; procyanidin; condensed tannin; flavan-3-ol; thiolytic degradation; epimerization; hydrogen peroxide oxidation
