P.M.R Evidence for biaxial Long-Range Couplings in Some Pyranosid-2-and 3-Ulose Derivatives
著者
Yotaro KONDO
(Kondo yotaro)
教養部
版
Publisher
出版地
奈良
出版者
奈良大学
上位タイトル
奈良大学紀要
(Memoirs of the Nara University).
Vol.3号,
(1974.
12)
,p.99-
105
識別番号
ISSN
03892204
抄録
Long_range coupling constants over four bonds (4J), which are closely correlated with stereochemistry, provide valuable information on structures, conformations and configurations of organic compounds (1,2). It is generally known that the occurrence of intensive 4J long-range couplings in saturated
cyclic systems requires a bonding system of the coupled protons in the planar W-arrangement(3,4), and indeed the protons of a 1,3-diequatorial orientationin a pyraroid carbohydrate with the chair conformation have been reported to show 4J. On the contrary, there have been several reports demonstrating occurrence of 1,3-diaxial long-range couplings in halogenocyclohexanones(5) and carbohydrates (6-8). In a previous paper (9), the author has reported a
small 4J long-range coupling constant (1.OHz) between H-2 and H-4 in methyl
2-O-acetyl-4, 6-O-benzylidene-a-D-Yibo-hexopyranosid-3-ulose(1).
