Several lignin model precursors have been submitted to zinc borohydride reductions and their resultant stereochemistries determined by NMR spectroscopy. Benzoyl carbonyls of alpha-aryloxy-beta-hydroxy systems were reduced without significant stereoselectivity to produce both threo and erythro isomers. However, protection of the beta-hydroxyl with either an acyl, alkyl, or silyl group and subsequent reduction gave erythro-specificities of up to 97%. A mechanism where competition for zinc cation complexation between the beta-hydroxyl and the alpha-aryloxy substituent is invoked to explain the observed results. Protection of the beta-hydroxyl prevents its complexation with the zinc cation; complexation occurs solely with the alpha-aryloxy substituent, affording the erythro-isomers.
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WASHINGTON STATE UNIV, INST BIOL CHEM, 467 CLARK HALL, PULLMAN, WA 99164 USAWASHINGTON STATE UNIV, INST BIOL CHEM, 467 CLARK HALL, PULLMAN, WA 99164 USA
DAVIN, LB
BEDGAR, DL
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WASHINGTON STATE UNIV, INST BIOL CHEM, 467 CLARK HALL, PULLMAN, WA 99164 USAWASHINGTON STATE UNIV, INST BIOL CHEM, 467 CLARK HALL, PULLMAN, WA 99164 USA
BEDGAR, DL
KATAYAMA, T
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WASHINGTON STATE UNIV, INST BIOL CHEM, 467 CLARK HALL, PULLMAN, WA 99164 USAWASHINGTON STATE UNIV, INST BIOL CHEM, 467 CLARK HALL, PULLMAN, WA 99164 USA
KATAYAMA, T
LEWIS, NG
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WASHINGTON STATE UNIV, INST BIOL CHEM, 467 CLARK HALL, PULLMAN, WA 99164 USAWASHINGTON STATE UNIV, INST BIOL CHEM, 467 CLARK HALL, PULLMAN, WA 99164 USA
机构:
WASHINGTON STATE UNIV, INST BIOL CHEM, 467 CLARK HALL, PULLMAN, WA 99164 USAWASHINGTON STATE UNIV, INST BIOL CHEM, 467 CLARK HALL, PULLMAN, WA 99164 USA
DAVIN, LB
BEDGAR, DL
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WASHINGTON STATE UNIV, INST BIOL CHEM, 467 CLARK HALL, PULLMAN, WA 99164 USAWASHINGTON STATE UNIV, INST BIOL CHEM, 467 CLARK HALL, PULLMAN, WA 99164 USA
BEDGAR, DL
KATAYAMA, T
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WASHINGTON STATE UNIV, INST BIOL CHEM, 467 CLARK HALL, PULLMAN, WA 99164 USAWASHINGTON STATE UNIV, INST BIOL CHEM, 467 CLARK HALL, PULLMAN, WA 99164 USA
KATAYAMA, T
LEWIS, NG
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WASHINGTON STATE UNIV, INST BIOL CHEM, 467 CLARK HALL, PULLMAN, WA 99164 USAWASHINGTON STATE UNIV, INST BIOL CHEM, 467 CLARK HALL, PULLMAN, WA 99164 USA