Nobuhiro Marubayashi

Novel yellow pigment from Pterocarpus santalinus: Biogenetic hypothesis for santalin analogs☆

A novel yellow pigment named santalin Y, related to red pigment santalin A was isolated from Pterocarpus santalinus. Its structure was determined by various spectral data including X-ray analysis. Biogenetic relationships for these compounds were also discussed.

Copper(II) and nickel(II) complexes of N,N′,N″,Nâ—-tetrakis(2-aminoethyl)-1,4,7,11-tetra-azacyclotetradecane (taei), -1,4,8,12-tetra-azacyclopentadecane (taep), and -1,5,9,13-tetra-azacyclohexadecane (taeh). Crystal structures of [Cu2(taep)][ClO4]4, [Cu2(taeh)][ClO4]4, and [Cu2(N3)(taeh)][ClO4]3

New octaamine dinucleating ligands, N,N′,N″,N‴-tetrakis(2-aminoethyl)-1,4,7,11-tetra-azacyclo-tetradecane (taei), -1,4,8,12-tetra-azacyclopentadecane (taep), and -1,5,9,13-tetra-azacyclohexadecane (taeh) and their complexes with CuII and NiII were synthesized. Of the 19 complexes isolated, the structures of [Cu2(taep)][ClO4]4, [Cu2(taeh)][ClO4]4, and [Cu2(N3)(taeh)][ClO4]3 were determined by X-ray crystal analysis. In all these complexes each copper is co-ordinated by two ring nitrogens and two pendant amino nitrogens, and the two CuN4 co-ordination sets face each other. In the azido complex the N3– is bonded to both coppers in an end-to-end fashion. The dinuclear complexes [Cu2L][ClO4]4(L = taei or taep) further incorporate various anions between the two coppers to form [Cu2X(L)][ClO4]3. However, only the azido complex was obtained with taeh. The results are discussed in terms of the ring-size effect.

A novel cholestane derivative as root growth inhibitor from Heloniopsis japonica

Abstract A novel cholestane glycoside, helojaposide ( 1 ), was obtained from Heloniopsis japonica. 1 exhibits an inhibitory activity for the root growth of rice.

A buffer zone in the crystal structure that governs the solid-state photodimerization of bulky olefins with the 1,4-dihydropyridine skeleton

Due to steric hindrance, bulky olefins cannot readily undergo solid-state photodimerization. UV irradiation of crystals of (4RS,1′RS)-methyl 1-phenyl-2-piperidinoethyl 1,4-dihydro-2,6-dimethyl-4-(2-thienyl)pyridine-3,5-dicarboxylate (1), however, affords a single product (4RS,8SR)-4a,8a-dimethoxycarbonyl-2,4b,6,8b- tetramethyl-3-[(1RS)-1-phenyl-2-piperidinoethoxycarbonyl]-7-[ (1SR)-1-phenyl-2-piperidinoethoxycarbonyl]-4,8-di(2-thienyl)- 1,4,4a,4b,5,8,8a,8b-octahydro-trans-cyclobuta[1,2-b : 3,4-b′]dipyridine (2), in quantitative yield. X-Ray analyses of 1 and 2 showed that 2 is a photodimer of 1 and proved that bulky olefins can undergo solid-state photodimerization. Although the molecular system and the molecular arrangement in the crystal of dimethyl 1,4-dihydro-2,6-dimethyl-4-(3-nitrophenyl)pyridine-3,5-dicarboxylate (3) are quite similar to those of 1, crystals of 3 cannot undergo solid-state photodimerization. Detailed inspection of the crystal structure of 1 revealed that there is a certain space between reacting molecules in the crystal to allow initiation of photodimerization. The space, designated as a buffer zone, buffers the steric hindrance from which the reacting molecules suffer when they approach each other. The buffer zone is formed by the disordered piperidine rings in 1, but there is no extra space in the crystal structure of 3. The present study has shown that the buffer zone in the crystal structure must be one of the prerequisite controlling factors for solid-state photodimerization.

A novel photochemical transformation of methyl 6-chloro-3,4-dihydro-4-methyl-3-oxo-2H-1,4-benzoxazine-8-carboxylate to β-lactams

Abstract A unique photoreaction of methyl 6-chloro-3,4-dihydro-4-methyl-3-oxo-2 H -1,4-benzoxazine-8-carboxylate in methanol gives four β -lactam compounds, methyl 6-chloro-2,9-dioxo-1-methyl-1-azaspiro[3.5]nona-5,7-diene-8-carboxylate and three stereoisomers of dimethyl 3-chloro-4-(1′-methyl-2′-oxoazetidin-4′-ylidene)-2-butene-1,1-dicarboxylate.