Fisetinidol- -catechin 4-0 methyl ether

The protonated species (73/74) presumably also served as precursor to the 4P-deuteriotri-0-methylfisetinidol (82) by delivery of hydride ion from the P-face in a predominant Sn2 mode. Compound (82) persistently formed also when fisetinidol-(4a- 8)- and (4p- 8)-catechin hepta-O-methyl ethers (68) and (70) were treated with Na(CN)BD3 in TEA. This observation prompted an investigation of the structural features of the substrates that direct the stereochemistry of the delivery of hydride ion at C(4) in intermediates of type (73/74). Whereas treatment of the epifisetinidol-(4p- 8)-catechin hepta-O-methyl ether (85) with Na(CN)BD3 afforded the 4P-deuteriotri-0-methylepifisetini-dol (87) (18.5%), tetra-O-methylcatechin (75) (32%) and the (25)-l,3-dideuterio-l,3-diarylpropan-2-ol [6%, enantiomer of compound (80)], the nEfisetinidol-(4p- 8)-catechin hepta-O-methyl ether (86) gave 4a-deuteriotri-O-methyl- nf-fisetinidol [13%, the enantiomer of compound (82)], tetra-O-methylcatechin (75) (24%) and the (25)-l,3-dideuterio-l,3-diarylpropan-2-ol [12%, enantiomer of (80)]. 

Scheme 8. Base-catalyzed pyran ring rearrangements of fisetinidol-(4a—>8)- and (4p— 8)-catechin 4-0 (E-ring) methyl ethers (100) and (101) ] 1...

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