332386-71-7Relevant academic research and scientific papers
Stereoselective synthesis of benzylated prodelphinidins and their diastereomers with use of the mitsunobu reaction in the preparation of their gallocatechin precursors
Krohn, Karsten,Ahmed, Ishtiaq,John, Markus,Letzel, Matthias C.,Kuck, Dietmar
experimental part, p. 2544 - 2554 (2010/09/05)
The tetrabenzylated catechin 9 was prepared by benzylation of the commercially available pure (+)-catechin (3) and cou-pled with the commercially unavailable pentabenzylated (-)-gallocatechin 10, prepared in a one-step Mitsunobu-type cyclization of the triol 8. The highly stereoselective synthesis of benzylated prodelphinidins - catechin-(4α→8)-gallocate-chin (13), gallocatechin-(4α→8)-gallocatechin (14), and gallo-catechin- (4α→8)-catechin (15) - is reported for the first time. The ESI(+)-CID mass spectra of the coupling products were found to feature regioselective retro-Diels-Alder (RDA) reac-tions and unusual sequential losses of pairs of C7H7' radicals (182 u) from the Na+ adduct ions.
Enantioselective synthesis of flavan-3-ols using a mitsunobu cyclization
Krohn, Karsten,Ahmed, Ishtiaq,John, Markus
experimental part, p. 779 - 786 (2009/09/06)
The synthesis of four flavan-3-ols with different substitution patterns and electron densities has been achieved in high stereo- and regioselectivity by a one-step Mitsunobu reaction from the corresponding diols, which were prepared by enantioselective Sharpless dihydroxylation of suitable olefins. The six-membered flavan-3-ols were the only cyclization products and the theoretically possible formation of five-membered rings during the Mitsunobu cyclization was not observed. The flavanols are important starting materials for the synthesis of dimers such as the procyanidins or other coupling products such as the flavan part of the potent DNA polymerase β inhibitor myristinin A. The enantioselectivities of both the Sharpless dihydroxylation and the Mitsunobu cyclization steps were monitored by chiral HPLC. Georg Thieme Verlag Stuttgart New York.
Enantioselective synthesis of epigallocatechin-3-gallate (EGCG), the active polyphenol component from green tea.
Li,Chan
, p. 739 - 741 (2007/10/03)
[reaction: see text]. Enantioselective synthesis of epigallocatechin-3-gallate (EGCG, 3b), the active polyphenol component from green tea, has been achieved by using a stereospecific cyclization of the Sharpless asymmetric dihydroxylation product 7c as the key step.
