Monitored aminolysis of 3-acylthiazolidine-2-thione : A new convenient synthesis of amide

3-Acylthiazolidine-2-thiones ($\text{1}$) were easily prepared and they were treated with several amines in dichloromethane to give amides $\text{4}$ in very high yields within a short time. Aminoalcohols and aminophenols were selectively converted into acylaminoalcohols and acylaminophenols, respectively, by this reaction. One can monitor the reaction by disappearance of the yellow color of the starting material $\text{1}$. Some amide alkaloids ($\text{1}$$\text{5}$–$\text{1}$$\text{8}$) have effectively been synthesized.     

Synthesis of polyimide and poly(imide-benzoxazole) in polyphosphoric acid

A polyimide made from 4,4′-diaminodiphenyl ether (ODA) and 3,3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA) was synthesized in polyphosphoric acid. Although the polymerization proceeded heterogeneously, a polyimide with an inherent viscosity of 0.90 was obtained, and a tough and flexible film was made from this polyimide. This polymerization was a one-step reaction including polycondensation and imidization; this was also confirmed by a model reaction between aniline and phthalic anhydride. Utilizing this polymerization method, 3,3′-dihydroxy-4,4′-diaminobiphenyl and 2 mol of 4-aminobenzoic acid were reacted in PPA, then BPDA was reacted to obtain an alternate copolymer containing imide and oxazole rings. This reaction gave a homogeneous solution of the poly(imide-benzoxazole). © 1993 John Wiley & Sons, Inc.     

Oxidative degradation of beta-diketiminate ligand in copper(II) and zinc(II) complexes

Copper(II) and zinc(II) complexes supported by a popular beta-diketiminate ligand (1(-), 2-mesitylamino-4-mesitylimino-2-pentene), [CuII(1)(AcO)] and [[ZnII(1)]2(mu-MeO)(mu-AcO)], have been demonstrated to undergo an oxidative degradation to give a ketone diimine derivative (2) under aerobic conditions. The crystal structures of the mononuclear copper(II) and dinuclear zinc(II) complexes of the beta-diketiminate ligand as well as the copper(II) complex of the modified ligand have been determined by X-ray crystallographic analysis. Mechanism for the oxidative degradation reaction of the beta-diketiminate ligand is also discussed.     

C-S bond formation reaction between a phenolate and disulfide-bridged dicopper(I) complexes

A novel C-S bond formation reaction took place, when a lithium phenolate derivative was treated with a disulfide-bridged dicopper(I) complex or a bis(micro-thiolato)dicopper(II) complex under very mild conditions. The reaction has been suggested to proceed via a disulfide-bridged (micro-phenoxo)dicopper(I) complex as the common reaction intermediate. Copper(II) complexes of the modified ligands containing a thioether group (products of the C-S bond formation reaction) have been isolated and structurally characterized by X-ray analysis as model compounds of the active site of galactose oxidase. Mechanism of the C-S bond formation reaction is also discussed in relation to the biosynthetic mechanism of the organic cofactor Tyr-Cys of galactose oxidase.     

Radical alpha-C-H hydroxyalkylation of ethers and acetal

[reaction: see text] Epsilonthers and an acetal were found to undergo direct intermolecular addition to aldehydes under the Et(3)B/air conditions. This study presents a very unique and simple means for the radical alpha-C-H hydroxyalkylation of oxygen-containing compounds.     

Two new 15,16-seco-cycloartane glycosides from Cimicifuga rhizome

Two new 15,16-seco-cycloartane glycosides (1, 2) were isolated from Cimicifuga Rhizome. Their structures were determined by spectroscopic analysis.     

A new determination of the absolute configuration of the chiral amine

A new method for assignment of the absolute configuration of the asymmetric carbon atom attached to an amino or imino group using rac.-3-hexadecanoyl-4-methoxycarbonyl-1,3-thiazolidine-2-thione (rac.-HDMTT) ($\text{4}$) is described.     

A dual ion-selective electrode detector for the simultaneous detection of bromine- and chlorine- containing compounds in gas chromatography

A dual ion-selective electrode gas chromatographic detector which allows the simultaneous detection of chlorine- and bromine-containing compounds through two-channel operation is described. Components eluted from the g.c. column are hydrogenated, the hydrogen chloride and hydrogen bromide produced being absorbed in a standard solution of halide; the ion concentrations in the resulting solution are monitored by chloride- and bromide-selective electrodes. The dual electrode detector gives two chromatograms simultaneously, one selective for chlorine- and bromine-containing compounds and the other for bromine-containing compounds. The response ratio, i.e., the peak area of the readout from the chloride channel divided by that from the bromide channel for the same compound, gives valuable information. The Cl/Br ratio in an eluted molecule can be determined accurately from the response ratio if a standard reference compound is injected simultaneously.     

Three new nortriterpene glycosides and two new triterpene glycosides from the bulbs of Scilla scilloides

Three new norlanostane-type triterpene glycosides, scillanostasides A, B, and C, and two new lanostane-type triterpene glycosides, scillanostasides D and E, were isolated from the bulbs of Scilla scilloides Druce (Liliaceae) along with one known norlanostane-type triterpene heptaglycoside, scillascilloside G-1. Their chemical structures were determined on the basis of spectroscopic data as well as chemical evidence.