An improved method for 14C-labelling of farnesylacetic acid and its geranyl ester

Farnesylacetic acid was efficiently labelled with 14C at the 5-position and gefarnate, a potent ulcer inhibitor, was prepared from it in radioactive form for use in metabolic studies. Condensation of [carbonyl-14C]acetyl chloride (5) with t-butyl 2-ethoxymagnesiomalonate (6) followed by acid-catalyzed deprotection and decarboxylation gave ethyl 3-oxo[3-14C]butanoate (8). Alkylation of the keto ester (8) with geranyl bromide (9) afforded the unsaturated keto ester (10), which was hydrolyzed and decarboxylated to give geranyl[2-14C]acetone (11). Grignard reaction of 11 with cyclopropylmagnesium bromide followed by treatment with hydrobromic acid yielded [4-14C]homofarnesyl bromide (13). Cyanation of 13 with potassium cyanide and subsequent hydrolysis gave [5-14C]farnesylacetic acid (1) in 6.1% yield from barium [14C]carbonate (3). Chlorination of 1 followed by esterification with geraniol afforded [5-14C]gefarnate (2) in 88% yield.     

Ionic-liquid-promoted decaborane dehydrogenative alkyne-insertion reactions: a new route to o-carboranes

Unlike in conventional organic solvents, where Lewis base catalysts are required, decaborane dehydrogenative alkyne-insertion reactions proceed rapidly in biphasic ionic-liquid/toluene mixtures with a wide variety of terminal and internal alkynes, thus providing efficient, one-step routes to functional o-carborane 1-R-1,2-C2B10H11 and 1-R-2-R'-1,2-C2B10H10 derivatives, including R = C6H5- (1), C6H13- (2), HC[triple bond]C-(CH2)5- (3), (1-C2B10H11)-(CH2)5- (4), CH3CH2C(O)OCH2- (5), (C2H5)2NCH2- (6), NC-(CH2)3- (7), 3-HC[triple bond]C-C6H4- (8), (1-C2B10H11)-1,3-C6H4- (9), HC[triple bond]C-CH2-O-CH2- (10); R,R' = C2H5- (11); R = HOCH2-, R' = CH3- (12); R = BrCH2-; R' = CH3- (13); R = H2C=C(CH3)-, R' = C2H5- (14). The best results were obtained from reactions with only catalytic amounts of bmimCl (1-butyl-3-methylimidazolium chloride), where in many cases reaction times of less than 20 min were required. The experimental data for these reactions, the results observed for the reactions of B10H13(-) salts with alkynes, and the computational studies reported in the third paper in this series all support a reaction sequence involving (1) the initial ionic liquid promoted formation of the B10H13(-) anion, (2) addition of B10H13(-) to the alkyne to form an arachno-R,R'-C2B10H13(-) anion, and (3) protonation of arachno-R,R'-C2B10H13(-) to form the final neutral 1-R-2-R'-1,2-C2B10H10 product with loss of hydrogen.     

One-dimensional coordination polymers containing penta-supertetrahedral sulfide clusters linked by dipyridyl ligands

Three new one-dimensional coordination polymers [Zn8S(SC6H5)14.C12H10N2](1), [Zn7CoS(SC6H5)14.C13H14N2](2) and [Zn8S(SC6H5)14.C13H14N2](3) have been prepared containing penta-supertetrahedral clusters and linear crosslinking dipyridyl ligands; the two complexes show optical transitions with band gaps of approximately 3.44 eV (1) and approximately 3.54 eV (2).     

Synthesis and Characterization of New Phthalocyanines Peripherally Fused to Four 13-Membered Tetrathiamacrocycles

The new metal-free phthalocyanine 5 and phthalocyaninatometals 6–8 (M=Co, Ni, or Zn) fused in peripheral positions with four 13-membered tetrathiamacrocycles were prepared by cyclotetramerization of 2, 3, 6, 7, 9, 10-hexahydro-5H-[1, 4, 8, 11]benzotetrathiacyclotridecine-13, 14–dicarbonitrile in the presence of a suitable metal salt or a strong organic base. In contrast to the aza- or oxamacrocycle-fused analogs, the solubility of these phthalocyanines is very low. Complexation of the tetrathiamacrocycles of 7 and 8 with Pd^II or Ag^I to form pentanuclear products was accomplished from their suspensions.     

Die Cardenolide von Acokanthera oppositifolia (LAM.) CODD. 3. Mitteilung . Isolierung weitere Cardenolide und teilweise Strukturaufklärung. Glykoside und Aglykone, 301. Mitt.

The presence of 19 cardenolides in the extracts from the seeds of Acokanthear oppositifolia (Lam.) CODD could be traced by means of paper chromatography. Thirteen of these cardenolides could be isolated in crystalline form, acovenoside A (= 2) being by far the major component. Of the other 12 crystalline substances, 5 could be identified with known cardenolides: 2′ = acofrioside L, 3 = acolongifloroside H, 14 = acovenoside C, 15 = acolongifloroside K, 16 = ouabain. The substances 1′, 1″, 4, 6, 7, 8 and 13 are very probably new compounds. Four of these were given trivial names and the following structures were proposed: 1″ = oppovenoside, probably 10 ; 4 = oppofrioside ( 5 ); 6 = acotaloside ( 6 ); 13 = opposide, probably 12 , cf. following publication [21]. Furthermore, the structure 8 has been proposed for acolongifloroside H.     

Synthesis of Three New Macrocyclic Tetraamide Ligands

A facile route is described for the synthesis of a series of macrocyclic tetraamides 1, 4, 9, 12 - tetraazacyclo - 2, 3, 6, 7, 10, 11, 14, 15-tetrabenzo-cetanan - 5, 8, 13, 16 - tetraone (TCTCT), 1, 4, 10, 13 - tetraazacyclo -2, 3, 6, 8, 11, 12, 15, 17-tetrabenzo-octadecan-5, 9, 14, 18-tetraone(TCTOT) and 1, 4, 10, 13-tetraaza-cyclo-2, 3, 11, 12-dibenzo-6, 8, 15, 17-dipyrdyl-octadecan-5, 9, 14, 18-tetraone (TCPOT) derived from 1, 2-diaminobenzene based on a stepwise approach using diacid dichloride (1, 2-diacid dichloride benzene, 1, 3- diacid dichloride benzene, 2, 6 - diacid dichloride pyridine) or mix dianhydrides for ring closure. This method is applicable for the preparation of a variety of receptors of various ring size, heteroatom substitution and pendant chains.     

Carbon ion irradiation induced surface modification of polypropylene

Polypropylene was irradiated with ¹²C ions of 3.6 and 5.4 MeV energies in the fluence range of 5×10¹³–5×10¹⁴ ions/cm² using 3 MV tandem accelerator. Ion penetration was limited to a few microns and surface modifications were investigated by scanning electron microscopy. At the lowest ion fluence only blister formation of various sizes (1–6 μm) were observed, but at higher fluence (1×10¹⁴ ions/cm²) a three-dimensional network structure was found to form. A gradual degradation in the network structure was observed with further increase in the ion fluence. The dose dependence of the changes on surface morphology of polypropylene is discussed.     

Diverse stereocontrol effects induced by weakly coordinating anions. Stereospecific olefin polymerization pathways at archetypal C(s)- and C(1)-symmetric metallocenium catalysts using mono- and polynuclear halo-perfluoroarylmetalates as cocatalysts

Counteranion effects on propylene polymerization rates and stereoselectivities are compared using Cs-symmetric Me2C(Cp)(Flu)ZrMe2 (1; Cp = C5H4,eta5-cyclopentadienyl; Flu = C13H8, eta5-fluorenyl) and C1-symmetric Me2Si(OHF)(CpR*)ZrMe2 (2; OHF = C13H16, eta5-octahydrofluorenyl; CpR* = eta5-3-(-)-menthylcyclopentadienyl) precatalysts activated with the mononuclear and polynuclear perfluoroarylborate, -aluminate, and -gallate cocatalysts/activators B(C6F5)3 (3), B(o-C6F5C6F4)3 (4), Al(C6F5)3 (5), Ph3C+B(C6F5)4- (6) Ph3C+FAl(o-C6F5C6F4)3- (7), Ga(C6F5)3 (8), and recently reported mono- and polymetallic trityl perfluoroarylhalometalates Ph3C+FB(C6F5)3- (9), Ph3C+FB(o-C6F5C6F4)3- (10), (Ph3C+)xFx[Al(C6F5)3]yx- (x = 1, y = 1, 11; x = 1, y = 2, 12; x = 2, y = 3, 13), Ph3C+(C6F5)3AlFAl(o-C6F5C6F4)3- (14), Ph3C+XAl(C6F5)3- (X = Cl, 15; X = Br, 16), and Ph3C+F[Ga(C6F5)3]2- (17). Temperature, propylene concentration, and solvent polarity dependence are surveyed in polymerizations catalyzed by 1 activated with cocatalysts 3-16 and with a 1:2 ratio of Ph3CCl and 5, and with a 1:2 ratio of Ph3CBr and 5, and by 2 activated with 3, 6, 7, 12, and 14. Remarkable stereocontrol with high activities is observed for 1 + 12 and 1 + 14. Polypropylene samples produced using C1-symmetric precatalyst 2 are subjected to microstructural analyses using stochastic models describing the relative contributions of enantiofacial misinsertion and backskip processes. A powerful technique is introduced for calculating interparametric correlation matrices for these nonlinear stochastic models. The collected results significantly extend what is known about ion-pairing effects in the case of Cs-symmetric precatalyst 1 and allow these findings to be applied to the case of C1-symmetric precatalyst 2 as an agent of isospecific propylene polymerization.     

Synthese und thermisches Verhalten von 6,8-Dimethylentricyclo[3.2.1.02,7]oct-3-enen; [3s 3s]-sigmatropische Umlagerungen von 6-Allenyl- und 6-Propargly-1- Methylen-cyclohexa-2,4-dienen in aromatische Kohlenwasserstoffe als Beispiele für konzertierte Semibenzol → Benzol-Umlagerungen

The tricyclic dimethylene hydrocarbons 5 , 6 , 7 , 8 and d₂- 5 , (Scheme 2), which are prepared by Wittig-reaction from the corresponding ketones, are rearranged, by heating, to 4-aryl-but-1-yne derivatives via the unstable 6-allenyl-1-methylene-cyclohexa-2, 4-diene intermediates (e.g. Scheme 14). Using the deuterium-labelled compound d₂- 5 , it was shown that the allenyl moiety, formed by a retro-Diels-Alder reaction (cycloreversion) of the tricyclic dimethylene compound, migrates with complete inversion in the final o-semibenzene-benzene rearrangement (Schemes 11 and 14). Reaction of 6-propargyl-cyclohexa-2, 4-dien-1-ones with triphenylphosphonium methylide gives 6-propargyl-1-methylene-cyclohexa-2 4-dienes, which immediately undergo a [3s, 3s]-rearrangement to form 4-aryl-buta-1, 2-dienes (Scheme 9). In contrast, the rearrangement of the corresponding 4-propargyl-1-methylene-cyclohexa-2, 5- dienes proceeds by a radical mechanism (Schemes 10 and 13).     

Oligonucleotide Analogues with a Nucleobase‐Including Backbone,Part 5, 2′‐Deoxy‐8‐(hydroxymethyl)adenosine‐ and 2′‐Deoxy‐6‐(hydroxymethyl)uridine‐Derived Phosphoramidites: Synthesis and Incorporation into 14‐Mer DNA Strands

The pairing propensity of new DNA analogues with a phosphinato group between O−C(3′) and a newly introduced OCH₂ group at C(8) and C(6) of 2′‐deoxyadenosine and 2′‐deoxyuridine, respectively, was evaluated by force‐field calculations and Maruzen model studies. These studies suggest that these analogues may form autonomous pairing systems, and that the incorporation of single modified units into DNA 14mers is compatible with duplex formation. To evaluate the incorporation, we prepared the required phosphoramidites 3 and 4 from 2′‐deoxyadenosine and 2′‐deoxyuridine, respectively. The phosphoramidite 5 was similarly prepared to estimate the influence of a CH₂OH group at C(8) on the duplex stability. The modified 14‐mers 6 – 9 were prepared by solid‐phase synthesis. Pairing studies show a decrease of the melting temperature by 2.5° for the duplex 13 ⋅ 9 , and of 6 – 8° for the duplexes 10 ⋅ 6 , 11 ⋅ 6 , 13 ⋅ 7 , and 14 ⋅ 8 , as compared to the unmodified duplexes.     

Studies on sulfinatodehalogenation XXI. A new and convenient syntheses of 2-(F-alkyl) aldehydes,alcohols, acids and ketones

Reaction of perfluoroalkyl iodides ( 1a–e ) with the unsaturated ethers such as 1-ethoxy-1-propene (2) , 1-methoxy-1-butene (3) under the sulfinatodehalogenation condition gave the corresponding 2-(F-alkyl) propanals ( 5a–e ) and butanals ( 6c, d ) very readily in high yield, which were converted to 2,4-dinitrophenylhydrazones ( 7a–e, 8c, d ) and characterized. The reaction products 5 and 6 were oxidized with Jone's reagent and reduced with NaBH₄ in ethanol to give the corresponding acids ( 9, 10 ) and alcohols ( 11, 12 ) in good yield. Treatment of compounds 5 and 6 with pyridine gave the dehydrofluorination products 13 and 14 . Under the same condition, perfluoroalkyl iodide reacted with 2-ethoxy-1-propene (4) only to form R_FSO₂Na and R_FH as the major products, but in aqueuous DMF (DMF: H₂O = 5:1) to give the perfluoroalkylacetone (15) in good yield. Thus, the reaction provides a convenient, effective new method for syntheses of these useful organofluorine intermediates.     

Azacrown ethers containing oximic and Schiff base sidearms - potential heteronuclear metal ion receptors

A simple synthetic pathway for the preparation of oxime- and Schiff base-containing aza- and diazacrown ethers is reported. N-Methoxymethyl-substituted aza-15-crown-5 and aza-18-crown-6 as well as N,N′-bis(methoxymethyl)-substituted diaza-18-crown-6 were treated with 5-bromosalicylaldehyde to produce the N-(2′-hydroxy-3′-carbonyl-5′-bromobenzyl)-substituted aza-15-crown-5 (8), aza-18-crown-6 (9) and N,N′-bis(2′-hydroxy-3′-carbonyl-5′-bromobenzyl)-substituted diaza-18-crown-6 (10) compounds. Compounds 8 and 10 were treated with hydroxylamine to give oxime-substituted ligands 12 and 13. A series of bis-Schiff base-containing diaza-18-crown-6 ligands were prepared by reacting 10 with 2-hydroxyaniline (to form 14), 5-nitro-2-hydroxyaniline (15), 2-aminopyridine (16), 2-hydrazinopyridine (17) and N-aminomorpholine (18). Compounds 12–18 are potential complexing agents for simultaneous binding of soft transition and hard alkali or alkaline earth metal ions in one molecule. These new oxime- and Schiff base-containing ligands interacted strongly with Na⁺ and K⁺ in methanol. The interaction of the aromatic portions of 9, 10, and 12–15 with transition metal ions was shown by the UV spectra of the metal ion complexes in 50% aqueous DMF. The X-ray structure of 10 is reported.     

Synthesis and Some Reactions of Quinoxalinecarboazides

Chlorination of ethyl(quinoxalin‐2(1H)one)‐3‐carboxylate 1 gave ethyl (2‐chloroquinoxaline)‐3‐carboxylate 2 ;thionation of 1 by P₂S₅ or 2 by thiourea yielded the same product 3 . Reaction of chloro compound 2 or thiocompound 3 with hydrazine hydrate gave pyrazolylquinoxaline 4 . The reaction of ester 1 with thiourea or hydrazine hydrate afforded pyrimido quinoxaline 5 or carbohydrazide 6 ; the reaction of 6 with carbon disulfide in basic medium followed by alkylation afforded oxadiazoloquinoxaline derivatives 7, 8a,b . Carboazide 9 was produced by reaction of 5 with nitrous acid. Compound 9 on heating in an inert solvent, with or without amines, in alcohols or hydrolysis in H₂O undergoes Curtius rearrangments to yield 10‐13 . Reaction of 13 with thiosemicarbazide gave triazoloquinoxaline 14 which on reaction with alkylhalides or hydrazine hydrate yielded 15a‐c while hydrolysis of 13 gave 3‐aminoquinoxalinone 16 which was used as an intermediate to produce 17‐20 .     

The photo-Nazarov cyclisation of 1-cyclohexenyl-phenyl-methanone revisited: II: Reaction between primary and secondary key intermediates

Trans-1-cyclohexenyl-phenyl-methanone (2) and enol 4, both key intermediates in the title reaction, react with each other in a Michael-type addition to form predominantly enol 10. This enol, kinetically stable but too reactive to be isolated, reveals its presence in the irradiated solutions by formation of the isomeric ketone 11 on acid catalysis, and by formation of the oxidation product 9 on exposure to atmospheric oxygen. In the absence of acid, formation of 10 competes significantly with the title reaction of cis-1-cyclohexenyl-phenyl-methanone (1). In a secondary photoreaction of 10, 1,6-hydrogen abstraction by the excited carbonyl group and cyclisation afford 13 and 14. Enols 4, 10, and 13, in striking contrast to enol ethers and to thermodynamically stable enols, are unstable towards atmospheric oxygen. Thus, 4 autoxidises to form five compounds (Ox-1 through Ox-5), 10 to form 9, and 13 to form 15.     

Two new sesquiterpene lactones from Ixeris chinensis

Phytochemical investigation of Ixeris chinensis NAKAI (Asteraceae) has resulted in the isolation of a new guaianolide-type sesquiterpene lactone, ixerochinolide (1) as well as the related glucoside, ixerochinoside (2). In addition, the known guaianolides, 8beta-hydroxy-3-oxo-guaia-4(15),10(14),11(13)-trien-1alpha,5alpha,6beta,7alphaH-12,6-olide (8beta-hydroxydehydrozaluzanin), 8beta,15-dihydroxy-2-oxo-guaia-1(10),3,11(13)-trien-5alpha,6beta,7alphaH-12,6-olide (lactucin), 3beta,8alpha,10alpha-trihydroxy-guaia-4(15),11(13)-dien-1alpha,5alpha,6beta,7alphaH-12,6-olide (10alpha-hydroxy-10,14-dihydro-desacylcynaropicrin) and 3beta-D-glucopyranosyloxy-8beta-(p-hydroxyphenylacetyloxy)-guaia-4(15),10(14),11(13)-trien-1alpha,5alpha,6beta,7alphaH-12,6-olide (8-epicrepioside) were identified. The structures were determined on the basis of spectral analyses, especially 1- and 2D NMR. Compound 1 exhibited significant cytotoxicity against human PC-3 tumor cells.     

Synthesis of (±)-4-Demethoxydaunomycinone by Double Diels-Alder Additions to 2, 3, 5, 6-Tetramethylidene-7-oxanorbornane

Sequential Diels-Alder additions of methylvinyl ketone and dehydrobenzene to 2, 3, 5, 6-tetramethylidene-7-oxanorbornane (4) yielded the (5, 12-epoxy-1, 2, 3, 4, 5, 6, 11, 12-octahydro-2-naphtacenyl) methyl ketone (10) which, in few steps was oxidized to a precursos of (±)-4-demethoxydaunomycinone. The preparations of two precursors of anthracyclinones, the (5-acetoxy-) and (12-acetoxy-1, 2, 3, 4-tetrahydro-2-naphtacenyl) methyl ketones (14, 15) are presented. The synthesis of 6, 13-epoxy-6, 13-dihydropentacene (8) is also reported.     

Luminescent Amphiphilic 2,6‐Bis(1‐alkylpyrazol‐3‐yl)pyridyl Platinum(II) Complexes: Synthesis,Characterization, Electrochemical,Photophysical, and Langmuir–Blodgett Film Formation Studies

Two series of novel platinum(II) 2,6‐bis(1‐alkylpyrazol‐3‐yl)pyridyl (N5Cn) complexes, [Pt(N5Cn)Cl][X] ( 1 – 9 ) and [Pt(N5Cn)(C?CR)][X] ( 10 – 13 ) (X=trifluoromethanesulfonate (OTf) or PF₆; R=C₆H₅, C₆H₄‐p‐CF₃ and C₆H₄‐p‐N(C₆H₅)₂), with various chain lengths of the alkyl groups on the nitrogen atom of the pyrazolyl units have been successfully synthesized and characterized. Their electrochemical and photophysical properties have been studied. Some of their molecular structures have also been determined by X‐ray crystallography. Two amphiphilic platinum(II) 2,6‐bis(1‐tetradecylpyrazol‐3‐yl)pyridyl (N5C14) complexes, [Pt(N5C14)Cl]PF₆ ( 7 ) and [Pt(N5C14)(C?CC₆H₅)]PF₆ ( 13 ), were found to form stable and reproducible Langmuir–Blodgett (LB) films at the air–water interface. The characterization of such LB films has been investigated by the study of their surface pressure–area (π–A) isotherms, UV/Vis spectroscopy, XRD, X‐ray photoelectron spectroscopy (XPS), FTIR, and polarized IR spectroscopy. The luminescence property of 13 in LB films has also been studied.     

Amino acids in the synthesis of heterocyclic systems. Synthesis of γ-(5-(1,2,4-Triazinylidene))-α,β-dehydro-α-amino acid derivatives and 6H-pyrido[1,2-d][1,2,4]triazin-6-ones

5-(1,2,4-Triazinyl) substituted enamines 3 react with 5(4H)-oxazolones 4 in acetic anhydride to give acetylated products 5 , while in toluene-acetic acid mixture nonacetylated products 9 are formed. Both types of products were isolated as (E,Z) mixtures. Compounds 5 and 9 rearrange into 6H-pyrido[1,2-d]-[1,2,4]triazin-6-ones 12 by heating in formic acid or in xylene, respectively. Compounds 5 are transformed in the presence of nucleophiles, such as sodium alkoxides or sodium amides via anionic form 10 into corresponding esters 13 and amides 14 of γ-(5-(1,2,4-triazinylidene)) substituted derivatives of α-amino-2-butenoic acid, which exist in 2-(Z),4-(Z) form.     

A new route to chelating bis(aryloxide) ligands and their applications to tantalum and titanium organometallic compounds

A new route to sterically tuned, chelating bis(aryloxide) ligands is described and demonstrated by the synthesis of 2,2'-ethylenebis(6-isopropylphenol) (1, H(2)BIPP) and transition metal complexes of its dianion. The utility of these ligands in titanium and tantalum organometallic chemistry is shown in the alkylation of (BIPP)TiCl(2) (7) to form (BIPP)TiMe(2) (8) and (BIPP)Ti(CH(2)Ph)(2) (9) and in the alkylation of (BIPP)TaCl(3) (10) and its base adducts to form (BIPP)TaMe(3) (14) and (BIPP)Ta(CH(2)Ph)(3) (13). Structural comparisons of the chelating 2,2'-ethylenebis(6-isopropylphenoxide) (BIPP) ligand with its analogous, nonchelating bis(2,6-dialkylaryloxide) ligand set are examined in the X-ray diffraction studies of (BIPP)TaCl(3)(THF).THF (11.THF) and (BIPP)Ta(CH(2)C(6)H(5))(3) (13).     

Electron transfer reactions. Reaction of tetracyclone,tetraphenylfuran and related substrates with potassium

The reaction of tetracyclone (1) with potassium in THF gave a mixture of benzoic acid (4), tetraphenylfuran (5) and cis-1,2-dibenzoylstilbene (6). The reaction of 1 with potassium in oxygen-saturated THF gave a mixture of 2-hydroxy-2,4,5-triphenyl-3(2H)furanone (3), 4, 5 and 6, whereas the reaction of 1 with potassium superoxide gave a moderate yield of 3,4,5,6-tetraphenyl-2-pyrartone (7), besides 3, 4, 5, and 6. The reaction of tetraphenylfuran (5) itself with potassium in THF gave a mixture of 6, 1,2,3,4-tetraphenylbutan-1-one (9), 2,3-diphenyl-1-indenone (10) and 2,3-epoxy-4-hydroxy-2,3,4-tnphenyltetralone-l (11), whereas practically no reaction occurred on treatment of 5 with potassium superoxide. Treatment of 10 with potassium in THF, however, gave a mixture of 4, dibenzo[a,c]-13-fluorenone (13), 2,3-diphenyl-2-hydroxyl-1-indanone (14) and 2,3-diphenylbenzofuran (15). A similar mixture of products consisting of 4, 13, 14 and 15 was obtained when the reaction of 10 with potassium was carried out in oxygen-saturated THF or when 10 was treated with potassium superoxide. Treatment of 2,3-diphenyl-2,3-epoxy-1-indanone (16) with potassium on the other hand, gave 10 in excellent yield. Cyclic voltammetric studies have been carried out to measure the reduction potentials of 1, 5, 10 and 16 in the generation of their radical anions. The radical anions of 1, 5, 10 and 16 were also generated pulse radiolytically in methanol and their spectra showed absorption maxima in the region 320–380 nm.