78284-44-3Relevant academic research and scientific papers
Acid-catalyzed rearrangements of flavan-4-phloroglucinol derivatives to novel 6-hydroxyphenyl-6a,11b-dihydro-6H-[1]benzofuro[2,3-c]-chromenes and hydroxyphenyl-3,2′-spirobi[dihydro[1]benzofurans]
Steynberg, Petrus J.,Steynberg, Jan P.,Hemingway, Richard W.,Ferreira, Daneel,McGraw, G. Wayne
, p. 2395 - 2403 (2007/10/03)
Acetic acid-catalyzed cleavage of proanthocyanidins in the presence of phloroglucinol gives a series of 2R procyanidin- and prodelphinidin-phloroglucinol adducts together with a novel 2S all-cis derivative implicating cleavage of the pyran ring and subsequent inversion of stereochemistry at C-2C. These flavan-4-phloroglucinol adducts also suffer dehydration to products with novel fused dihydrobenzopyran-dihydrobenzofuran rings. In addition, cleavage of the flavan C-10A-C-4C bond followed by dehydration results in unique 3,2′-spirobi[dihydro[1]benzofurans].
Synthesis of Condensed Tannins. Part 1. Stereoselective and Stereospecific Syntheses of Optically Pure 4-Arylflavan-3-ols, and Assessment of their Absolute Stereochemistry at C-4 by means of Circular Dichroism
Botha, Jacobus J.,Young, Desmond A.,Ferreira, Daneel,Roux, David G.
, p. 1213 - 1219 (2007/10/02)
Stereoselective and also stereospecific condensation at C-4 of flavan-3,4-diols of known absolute configuration with phloroglucinol and resorcinol in acid medium proceeds at ambient temperatures with partial retention of configuration for 2,3-trans-isomers and with inversion for 2,3-cis-analogues.Circular dichroism spectra of the resultant 4-arylflavan-3-ols all exhibit multiple Cotton effects.The sign of high intensity Cotton effects to low wavelength, contributed by aryl chromophores at C-4, may almost invariably be correlated with the absolute configuration at this chiral centre of 2,3-trans-3,4-trans, 2,3-trans-3,4-cis, and 2,3-cis-3,4-trans-isomers.
