Masako Ueyama

Conformation of 1- and 3-deazaadenosines in solution as studied by 1H nuclear magnetic resonance spectroscopy (1)

Abstract 1H nuclear magnetic resonance spectra of 1 - (II) and 3-deazaadenosines (III) together with adenosine (I) in dimethylsulfoxide have been examined. Features of coupling constants indicate that the furanose rings of I, II, and III have similar conformational preferences and that conformations about the 4′-C–5′-C bond are preferentially gauche-gauche . Nuclear Overhauser effect and spin-lattice relaxation-time measurements demonstrate that II predominantly adopts the syn -conformation similar to that of I, whereas that of III has a greater anti (freely rotating) component. The results suggest that the syn -conformation in II as well as I is stabilized presumably through a hydrogen bond between the 3-N and 5′-hydroxyl group.

Sesquiterpenoids. Part XLVII. Structure, configuration, conformation, and thermal rearrangement of furanodienone, isofuranodienone, curzerenone, epicurzerenone, and pyrocurzerenone, sesquiterpenoids of Curcuma zedoaria

Five new furo-sesquiterpenoids, furanodienone [(1E,4E)-8,12-epoxygermacra-1(10),4,7,11-tetraen-6-one](1), isofuranodienone [(1E,4Z)-8,12-epoxygermacra-1(10),4,7,11-tetraen-6-one](2), curzerenone [6,7-dihydro-5β-isopropenyl-3,6β-dimethyl-6-vinylbenzofuran-4(5H)-one](3), epicurzerenone [6,7-dihydro-5α-isopropenyl-3,6β-dimethyl-6-vinylbenzofuran-4(5H)-one](4), and pyrocurzerenone [6,7-dihydro-1,5,8-trimethylnaphtho-[2,1-b]furan)(15) have been isolated from the rhizomes of Curcurma zedoaria Roscoe, and their structures have been elucidated on the basis of chemical and spectroscopic evidence. The conformation of the ten-membered ring in (1) and (2) has been determined by use of the intramolecular internuclear Overhauser effect. Thermal rearrangements of these sesquiterpenoids are described.

Direct introduction of a benzoyloxy substituent at the ring junction of fused β-lactam rings

Treatment of the 7-phthalimido-3-methyl-ceph-3-em-4-carboxylate (1) and 6-phthalimido-penicillins (4) with t-butyl perbenzoate in the presence of copper(I) chlride gave compounds bearing a benzoyloxy substitutent at the ring junction of the fused β-lactam rings, (2) and (5) respectively.