TY - JOUR
T1 - Thermal and photochemical epimerization/equilibration of carbohydrate cobaloximes
AU - Yu, G. X.
AU - Tyler, D. R.
AU - Branchaud, B. P.
N1 - Copyright:
Copyright 2011 Elsevier B.V., All rights reserved.
PY - 2001/8/24
Y1 - 2001/8/24
N2 - Epimeric carbohydrate alkyl cobaloximes 4:5, 9:10, and 12:13 can be equilibrated thermally or photochemically. In each case, one isomer is strongly favored: exo-3-deoxy-3-pyridyldimethylgly-oximatocobalt-1, 2:5,6-di-O-isopropylidene-α-D-glucofuranose 4 for the 4:5 epimer pair, exo-3-deoxy-3-pyridyldimethylglyoximatocobalt-5-O-carboxymethyl-1, 2-O-isopropylidene-α-D-xylofuranose 9 for the 9:10 epimer pair, and equatorial 1-deoxy-1-pyridyldimethylglyoximatocobalt-2,3,4, 6-tetra-O-benzyl-β-D-glucopyranose 12 for the 12:13 epimer pair. These data indicate that there is a strong facial preference for the coupling of py(dmgH)2Co· radicals with alkyl R· free radicals, with the preferred kinetic path leading to the more stable product.
AB - Epimeric carbohydrate alkyl cobaloximes 4:5, 9:10, and 12:13 can be equilibrated thermally or photochemically. In each case, one isomer is strongly favored: exo-3-deoxy-3-pyridyldimethylgly-oximatocobalt-1, 2:5,6-di-O-isopropylidene-α-D-glucofuranose 4 for the 4:5 epimer pair, exo-3-deoxy-3-pyridyldimethylglyoximatocobalt-5-O-carboxymethyl-1, 2-O-isopropylidene-α-D-xylofuranose 9 for the 9:10 epimer pair, and equatorial 1-deoxy-1-pyridyldimethylglyoximatocobalt-2,3,4, 6-tetra-O-benzyl-β-D-glucopyranose 12 for the 12:13 epimer pair. These data indicate that there is a strong facial preference for the coupling of py(dmgH)2Co· radicals with alkyl R· free radicals, with the preferred kinetic path leading to the more stable product.
UR - http://www.scopus.com/inward/record.url?scp=0035943264&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0035943264&partnerID=8YFLogxK
U2 - 10.1021/jo005595v
DO - 10.1021/jo005595v
M3 - Article
C2 - 11511240
AN - SCOPUS:0035943264
SN - 0022-3263
VL - 66
SP - 5687
EP - 5691
JO - Journal of Organic Chemistry
JF - Journal of Organic Chemistry
IS - 17
ER -