Preparation and characterization of some new diaminobisimides

A series of stable diaminobisimides (DABIs) has been prepared as alternatives to simple aromatic diamines for use in the preparation of condensation polymers. These DABIs were prepared by reacting two moles of an aromatic diamine with one mole of a dianhydride under conditions that minimize side reactions and the formation of oligomers. In many cases, the pure DABI consisting of two moles of the diamine and one mole of the dianhydride (i.e. the 2:1 product) can be obtained free of oligomers (i.e. the 3:2, 4:3 etc products). The studies have shown that the major factor determining the yield and purity of a DABI is the extent of conjugation between the two amino groups in the starting diamine: to a lesser extent steric effects in the diamines also influence the product composition. The reaction conditions necessary to produce these new DABIs are described together with extensive characterization of these materials by FTIR,1H and 13C NMR and gel permeation chromatography. The results indicate that pure DABIs are more manageable materials than the impure. insoluble materials previously described in the literature and can be used successfully to produce useful high-temperature stable polymers.

Interfacial Charge Separartion in the Photoreduction of Water: Effects of Colloidal Silica

It has been confirmed that colloidal silica can retard reverse electron transfer in the photochemical system water/ tris (2,2′- bipyridine )ruthenium dication/triethanolamine/zwitterionic viologen . However, the beneficial effect of silica diminishes as the concentration of the electron donor ( triethanolamine ) increases. Substantially higher yields of hydrogen have been obtained with 2,2′,6,6′-tetramethyl-1,1′- di (3-sulfonatopropyl)-4,4′-bipyridinediium which is more stable and has a more favourable potential than previously used electron-transfer agents.

Photoreduction of deazaflavin. Spectroscopic investigations

Photophysical and photochemical properties of deazaflavin (3,10-dimethylpyrimido[4,5-b]quinoline- 2,4-(3H,10H)-dione) and some of its 1,5-dihydro derivatives have been investigated. Contrary to earlier reports the photodimer of deazaflavin is non-luminescent throughout the temperature range 77-295 K. Excitation of deazaflavin in the presence of oxalate anion (acetate buffer pH 5.0) causes photodimerization with quantum efficiencies exceeding unity. A mechanism involving a triplet excimer of deazaflavin has been proposed for this reaction.

Solar reduction of water. III. Improved electron-transfer agents for the system water-Tris(2,2'-bipyridine)ruthenium dication-ethylenediaminetetraacetic acid-platinum

In searching for more effective electron-transfer agents for the photochemical production of hydrogen by the title system 16 diquaternary pyridinium compounds have been evaluated. At pH values of 5.0 and 7.0 the best results are obtained with compounds with potentials near -0.5 and -0.6 V, respectively, provided they are stable. Kinetic measurements show that the rate of quenching of *Ru(bpy)32+ decreases and the rate of the catalysed reduction of Haq+ increases as the potential becomes more negative, so that a range of optimum potential is created. The pH dependence of hydrogen formation arises from the effects of pH on the rate of reduction of Haq+. The main loss of diquaternary pyridinium compounds during irradiation is caused by catalytic hydrogenation. Therefore compounds that are more resistant to hydrogenation than methylviologen are more effective in the production of hydrogen, provided their potentials fall within the required range.

Solar reduction of water. I. Competition between light-induced hydrogen formation and hydrogenation of methylviologen in the system water-Tris(2,2'-bipyridine)ruthenium dication-ethylenediaminetetraacetic acid-platinum

The light-induced formation of hydrogen in the system H2O-Ru(bpy)32+-mv2+-edta-Pt (mv, inethylviologen) is accompanied by the hydrogenation of mv2+ to give the 1-methyl-4-(1'-methylpiperidin-4'-yl)pyridinium cation (1). The production of hydrogen is decreased by factors that favour the formation of this cation. The extent of hydrogenation depends on the pH of the mixture, the amount and type of catalyst present, and the partial pressure of hydrogen during irradiation.

Solar reduction of water. II. Inhibition of the hydrogenation of methyl viologen in the system water-Tris(2,2'-bipyridine)ruthenium(II) dication-ethylenediaminetetraacetic acid-platinum by sulfur compounds

The light-induced formation of hydrogen in the system H2O-Ru(bpy)32+-mv2+-edta-Pt is accompanied by the hydrogenation of mv2+. This hydrogenation process is suppressed by the addition of cysteine or glutathione. Substantial increases in the turnover numbers of mv2+ and the yields and rates of hydrogen production are achieved.

Carbocyclic analogues of equol for the immunization of sheep against clover disease. I. Hydroxynaphthalenones

Racemic and optical isomers of 7-hydroxy-3-(p-hydroxyphenyl)-3,4- dihydronaphthalen-1(2H)-one (1) have been synthesized and the configurations of the optical isomers assigned by o.r.d. spectrometry. Derivatives of these 3,4-dihydronaphthalen-1(2H)-ones with aminooxyacetic acid were prepared and the 1,2,3,4-tetrahydronaphthalene (24) corresponding to (1) was synthesized.

Isolation of unstable alkaloids from Erythrophleum chlorostachys (Leguminosae)

Unstable 2-methylaminoethyl esters from E. chlorostachys can be isolated with careful pH control and then manipulated as their stable hydrochlorides. A large-scale extraction and counter- current distribution separated two new crystalline alkaloid hydrochlorides, namely norerythrostachaldine hydrochloride, C23H37NO5,HCl, and a second salt, C24H37NO7,HCl. Four new monoacetates are tentatively identified as the 3β-acetoxy derivatives of the two new alkaloids, norerythrostachamine, and norerythrophlamine. Norerythrophlamine has been isolated for the first time as its crystalline hydrochloride.

Structure of norerythrostachaldine, a cytotoxic alkaloid from Erythrophleum chlorostachys (Leguminosae)

Norerythrostachaldine (1) and its naturally occurring 3β-acetate (2) are highly cytotoxic aldehydic bases considered to be 19- oxonorcassaidine and its 3β-acetate. The carbon skeleton, stereochemistry and position of oxygen substituents were established by lithium aluminium hydride reduction of (1) to give the tetrol (3) which was identical with a sample prepared from norerythrostachamine (4).

Tumour inhibitory plants. New alkaloids from the bark of Erythrophleum chlorostachys (Leguminosae)

A new alkaloid, norerythrostachamine (1), and its rearrangement product, norerythrostachamide (2), from extracts of E. chlorostachys bark, are shown to be the ester and amide of 2-methylaminoethanol and 3β,7β-dihydroxycass-13(18)-en-16,19-dioic acid 16-methyl ester already known from borohydride reduction of erythrophlamic acid. A second isomeric pair, norcassamidine (3) and norcassamidide (4), derived from 2-methylaminoethanol and cassamidic acid, are described as well as a new amide, norcassaidide (9, formed from the same amine and cassaidic acid. The known alkaloids cassaidine (6), cassamidine (7) and norerythrophlamide (8) were also isolated.

ω-Hydroxyisodillapiole, a new cinnamyl alcohol from Piper novae-hollandiae

A minor constituent of the wood of Piper novae-hollandiae is shown by synthesis from dillapiole to be the previously unknown ω-hydroxyisodillapiole (2)((E)-2,3-dimethoxy-4,5-methylenedioxyoinnamyl alcohol).

New imidazole alkaloids from Cypholophus friesianus (Urticaceae). The structures and synthesis of cypholophine and O-acetylcypholophine

Two new imidazole alkaloids cypholophine (1a) and O-acetylcypholophine (1b), isolated from Cypholophus friesianus (family Urticaceae), have been synthesized. A non-alkaloidal constituent of Cypholophus decipiens has been identified as the previously known terpenoid lactone, loliolide (2).

Tumour inhibitory plants. Amides of Piper novae-hollandiae (Piperaceae)

A new amide, Δαβ-dihydropiperine (I), has been isolated from the wood of Piper novae-hollandiae and synthesized. Two amides, N-isobutyl-trans- 2,trans-4-octadienamide and 3,4-methylenedioxycinnamoylpiperidide, previously unreported from natural sources but known from synthesis, were present as were five amides already established as plant constituents, namely, N-isobutyl-trans-2,trans-4-decadienamide, fagaramide, piperlonguminine, piperine, and an isomer of piperine, probably chavicine, as well as the essential oil, dillapiole. Δαβ-and Δβγ-Dihydro-piperlonguminine, (VIII) and (IX), and Δβγ-dihydropiperine (III) were also synthesized.

Tumour inhibitory plants. The alkaloids of Bruguiera sexangula and Bruguiera exaristata (Rhizophoraceae)

Tropine and tropine esters of acetic, propionic (a new natural ester), n-butyric (a new natural ester), isobutyric, α-methylbutyric or isovaleric, and benzoic acids have been identified in crude alkaloid mixtures from the bark of B. sexangula and B. exaristata. The major component of the mixtures from both species was a new alkaloid, brugine, (+)-tropine 1,2-dithiolan-3-carboxylate.

Synthesis of the tumour-inhibitory alkaloids, ellipticine, 9-methoxyellipticine, and related pyrido[4,3-b]carbazoles

Orthophosphoric acid has been found to accomplish the previously unsuccessful cyclization of azomethines of 3-formylcarbazoles and aminoacetal to substituted pyrido[4,3-b]carbazoles according to a scheme proposed by Cranwell and Sexton. By this method, there have been prepared 6,11-dimethyl-(ellipticine), 5,6,11-trimethyl-, 5,9,11- trimethyl-, 9-methoxy-5,11-dimethyl- (9-methoxyellipticine), 9-methoxy- 5,6,11-trimethyl-, 9-bromo-6,11-dimethyl-, and 9-nitro-5,11-dimethyl- 6H-pyrido[4,3-b]carbazole.

The structure of methoxyellipticine

Methoxyellipticine is shown to be 9-methoxy-5,11-dimethyl-6H- pyrido[4,3-b]-carbazole (IV).

The Structure of Polygodial: A New Sesquiterpene Dialdehyde from Polygonum hydropiper L

A pungent substance, polygodial, isolated from Polygonum hydropiper L. is shown to be drim-7-en-11,12-dial (I), a new dialdehyde structurally related to sesquiterpene lactones from Drimys species.

Synthesis of Pleurospermine, the Leaf Alkaloid of Cryptocarya pleurosperma White and Francis

4'-Hydroxy-3'-methoxy-2-(2-piperidyl)acetophenone was synthesized and found to be identical with natural racemic pleurospermine. Its biogenetic relationship to cryptopleurine, the bark alkaloid, is discussed.

Preparation of aryl aldehydes from arly methyl ketones

Arylglyoxylic acids can be readily obtained from solid my1 methyl ketones by permanganate oxidation of the latter in pyridine solution at 15 �C. Decarboxylation of the glyoxylic acids in NN-dimethyl-p-toluidine affords good yields of the aryl aldehydes containing 1, 2, 3, and 4 aromatic rings.