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Irradiation of a benzene solution containing 1-diphenylvinylidene-2,2,3,3-tetramethylcyclopropane and an excess of acrylonitrile in the presence of Michler's ketone afforded 2-cyano-1-diphenylvinylidene-4,4,5,5-tetramethylcyclopentane in high yield.

The photochemical properties of 1,2-diarylcyclopropanes bearing an acetylphenyl group were studied by product analysis and laser flash photolysis. All cyclopropanes showed efficient cis−trans photoisomerization followed by inefficient isomerization to 1,3-diarylpropenes. All the products were unquenched by the addition of triplet quencher, 2-methyl-1,3-butadiene (ET ≃ 60 kcal mol-1), whereas molecular dioxygen gave oxygenated products. Triplet 1,3-biradicals generated from a short-lived acetophenone-like triplet (≲1 ns) were observed as intermediates in these reactions through nanosecond laser flash photolysis. Polar substituent effects on the lifetime of the 1,3-biradicals were small, except for a heavy atom effect in the case of Br. Spin−orbit coupling calculations on model 1,3-biradicals show a negligible effect on polar substituent and thus predict a negligible effect on the intersystem crossing rate. Conjugated biradicals in general now seem unlikely to show the “ionic character effect” on intersyste...

The formation of ethers was catalyzed by 5,11,17,23,29,35-hexa-p-t-butyl-37,38,39,40,41,42-hexakis(3,6,9-trioxadecyloxy)calix[6]arene (1). It was found that the calixarene-catalyzed reaction of phe...

Irradiation of an acetonitrile-methanol (4:1) solution containing 1-cyanonaphthalene and allyltrimethylsilane (1) through Pyrex filter (>280 nm) regioselectively gave 3-cyano-4,5-benzotricyclo[4.2.1.0 3,8 ]-4-nonene. The photoreaction of 2-cyanonaphthalene, 1-cyano-2-methylnaphthalene, 1-cyano-4-methylnaphthalene, 1,5- and 2,3-dicyanonaphthalenes with 1 gave the corresponding benzotricyclic compounds also in a regioselective manner. However, the photoreaction of 2,3-disubstituted 1,4-dicyanonaphthalenes with 1 gave no benzotricyclic compounds, but only the allyl substitution and reductive allylation products. These photoreactions were initiated by photoinduced electron transfer from 1 to the excited singlet states of mono- and dicyanonaphthalenes. The reductive allylation products from the former cyanonaphthalenes afforded the benzotricyclic compounds by an intramolecular (2 π +2 π ) photocycloaddition in good yields. The regioselectivity in the allylation reaction is discussed on the basis of the results of MO calculations of the radical anions of mono- and dicyanonaphthalenes.

This paper deals with the ability ofp-tert-butylcalix[6]arene derivative1, which has six 3,6,9-trioxadecyl substituents at the phenolic oxygens, to encapsulate CT complexes of alkadienes with iodine. By adding I2 to alkadienes in CH2Cl2 in the presence of1, the absorbance at 363 nm, which was ascribed to I3− ion, increased in the order: 1,5-hexadiene

The phenanthrene-sensitized photoreaction of electron-deficient alkenes with disilanes in acetonitrile gave silylated alkanes in high yields. The photosilylation occurred in a highly regioselective manner at the position β to the electron-withdrawing groups of the alkenes. With asymmetrically substituted disilanes and polysilanes, silyl groups bearing more bulky substituents were preferentially introduced to the alkenes. The photoreactions were sensitized by aromatic hydrocarbons such as phenanthrene and triphenylene, but not by pyrene or anthracene. In the absence of aromatic hydrocarbons, the photoreactions were not appreciable. The key step of the photoreactions was the reaction with the radical anions of electron-deficient alkenes of silyl radicals, which were generated by a nucleophile-assisted cleavage of the radical cations of disilanes and polysilanes. The mechanistic features of the photoreaction are discussed.

(η 3 -Allyl)Fe(CO) 2 NO complexes undergo conjugate addition to α,β-unsaturated carbonyl compounds to give the corresponding δ,ϵ-unsaturated carbonyl compounds in good yields. The reaction of (η 3 -1-or 2-trimethylsiloxyallyl) Fe(CO) 2 NO complexes with α,β-unsaturated ketones affords 1,6- or 1,5-diketones, respectively. (η 3 -1-Acetonylallyl)Fe(CO) 2 NO complexes also react with α,β-unsaturated carbonyl compounds to give 1,8-dicarbonyl compounds. The mechanisms and reactivity of these conjugate addition reactions are discussed.

γ-Radiolysis reactions of eight 5-fluorouracil (5-FU) derivatives having sulfonyl group-containing suhstituents at the 1-position and five 5-fluorouridine (5-FUR) derivatives having thioureido group-containing substituents were studied under the conditions where hydrated electron (e aq - ) and hydroxyl radical (HO . ) become the principal reactive species. The 5-FU and 5-FUR derivatives were radiolyzed to give 5-FU and 5-FUR, respectively. The efficiency of the reactions depended upon the nature of reactive species and also upon the nature of substituents. The reactivity features of the γ-radiolysis reactions are discussed

The dichlorocarbene generation reaction from CHCl3 and solid KOH in CH2Cl2 was catalyzed by the p-t-butylcalix[6]arene derivative 1 which bears six 3,6,9-trioxadecyl substituents on the phenolic oxygens. Dichlorocarbene generated by this method reacted efficiently with alkenes and amides to give dichlorocyclopropane derivatives and nitriles, respectively, in high yields. The reaction with alkadiene having isolated double bonds gave mixtures of the mono- and bis-dichlorocarbene adducts, but the monoadduct formation always predominated. The catalytic action of the calixarene and the reactivity features of dichlorocarbene generated by the above procedure are discussed on the basis of kinetic measurements. They are also compared with those of the 18-crown-6-catalyzed reactions.

1-Alkenyl-2-(2′,2′-diphenylethenylidene)cyclopropanes thermally rearranged to 4-(diphenylethenylidene)cyclopent-1-enes at relatively low temperature (≤373 K). Measurement of activation parameters revealed that the reactivity and mode of the reaction largely depend on structures of starting materials and products.

Electronic interaction between C α C β σ bonds of the alkyl groups and β-orbitals on the 4-acetylphenyl ring in the lowest triplet state of 4-acetylphenylpropane and 1,2-bis(4-acetylphenyl)ethane was studied as a function of C α C β bond length by means of semi-empirical MNDO MO calculations. The transition and final states of the title reaction were energetically estimated from potential curves of the lowest and σ,σ* triplet states to determine energy barriers and heats of reaction. The reactivity features of the photoreaction were discussed on the basis of these results.

One-pot reaction of allyl halides with [Bu 4 N] + °Fe(CO) 3 (NO)] - follo- wed by treatment with 1,2-bis(diphenylphosphino)ethane gave β,γ-unsatu- rated acyl iron complexes in good yields via regioselective carbonyla- tion with retention of configuration of the allylic double bond. β,γ-Un- saturated carboxylic acid esters and amides were prepared upon treat- ment of the acyl iron complexes with alcohols and amines in the presence of iodine

Physical and chemical properties of radical cations generated from Ar2C=CH(CH2)nCH=CAr2 (Ar = 4-CH3OC6H4, n = 2–4) were studied by use of pulse radiolysis and γ-radiolysis techniques. When n = 3 and 4, 1,4-radical cations were formed via intramolecular cyclization of initially formed radical cations. The 1,4-radical cations were trapped by molecular dioxygen at the diarylalkylmethyl radical site, which suggests the “distonic” character of the species.

A variety of mitomycin C analogs were synthesized from mitomycin A and their biological activities were studied. Mitomycin A (1) underwent nucleophilic displacement reactions involving intramolecular hydrogen migrations upon treatment with nitrogen nucleophiles bearing mobile hydrogens, but the mode of hydrogen migration depended on the nature of the nucleophiles. The reaction with alkoxyamines gave compounds 6 and 7 which have the 5H-6-alkoxyimino-4,7-dione structure in ring A of 1. However, the reaction with hydroxylamine and benzoylhydrazine afforded compounds 11 and 13 which have the 4-hydroxy-6-hydroxyimino-7-one structure and the 4-hydroxy-6-hydrazono-7-one structure, respectively, in ring A of 1. These products were converted into various types of mitomycin C derivatives by methylation with methyl iodide or dimethyl sulfate. The mechanistic features of these reactions are discussed. The in vitro and in vivo biological activities were tested by using P388 leukemia and Sarcoma 180 tumor cells. Several of the synthesized compounds exhibited better activity than that of mitomycin C.

The λ-Radiolysis reactions of mitomycin C (1) and its derivatives were studied in the hope of developing a radiation-induced drug (RID). The λ-radiolysis reactions were carried out in aqueous solutions under the condition where hydrated electron (e - aq ) was generated as a principal reactive species. The competitive λ-radiolysis studies revealed that the rate constants for the reactions of 1 with e - aq at room temperature was 3.6×10 10 dm 3 mol -1 s -1 . Among mitomycin C derivatives, the 5H-6-alkoxyimino derivatives 11 and 12, and compound 13 in which ring A of 1 has the 4-hydroxy-6-hydroxyimino structure cleaved to give 1. The mechanic aspect of these λ-radiolysis reactions is discussed

The binding properties of p-(phenylazo)calix[n]arenes (n = 6 and n = 4) for metal ions have been studied. The calixarenes show a highly selective binding ability toward Ag+, Hg+, and Hg2+. This property can be explained in terms of a metal ion-induced azo/hydrazone tautomerism. The Ag+ ion forms complexes with the azocalixarenes by binding with their hydrazone tautomers.

Photoreactions of arylmethylsilanes, -germane, and -stannane with 1,4-dicyanonaphthalene (DCN) and 9,10-dicyanoanthracene (DCA) were studied under various conditions. The arylmethylation of DCN and DCA occurred in the photoreaction under nitrogen atmosphere, whereas the oxygenation of the arylmethyl organometallic compounds occurred in the photoreaction under oxygen atmosphere. Key intermediates in these reactions in acetonitrile were radical ions which were generated via photoinduced electron transfer from the arylmethyl organometallic compounds to the excited singlet of DCN or DCA. The cleavage of the carbon–metal bond of the radical cations of the arylmethyl compounds resulted in the formation of arylmethyl radicals. The radicals reacted then with the radical anions of DCN and DCA to produce the arylmethylated compounds or reacted with oxygen to produce the oxygenated compounds. The efficiency of the photoreactions was affected by solvents and added materials to the reaction systems. In the photoreacti...

1,2-Bis(4-acetylphenyl)ethanes undergo a novel meso-dl photoisomerization via the C1-C2 σ bond cleavage from their excited triplets. Comparison between acyclic and cyclic derivatives suggests that the energy barrier for the conformational change leading to the transition state with maximum σ-π orbital interaction, as well as the molecular strain estimated by MM2 calculations, plays an important role in determining the photochemical reactivity of the compounds.

The 9,10-Dicyanoanthracene-sensitized photoreaction of (2′,2′-diaryl-vinylidene) cyclopropanes with organic carbonitriles gave 2-substituted 3-(2,2-diarylvinylidene)-1-pyrrolines via photoinduced electron transfer.

Photoreactions of 1,2- and 1,4-dicyanobenzenes (o- and p-DCB) with allylic silanes, germanes, and stannanes in acetonitrile were studied under various conditions. In these photoreactions, one of cyano groups of o- and p-DCB was replaced by allylic groups. With trimethyl(3-methyl-2-butenyl)silane, -germane, and -stannane, the photosubstitution occurred at both α- and γ-positions of the allylic moiety in a constant ratio, regardless of the kinds of metals. 1,3-Dicyanobenzene (m-DCB) was less reactive to the photosubstitution reaction. The reactivity of group 14 organometallic compounds increased in the order: Si- < Ge- < Sn-compounds. The photoreactions were sensitized by aromatic hydrocarbons such as phenanthrene and triphenylene, and also accelerated by adding Mg (ClO4)2 and alkylbenzenes. Quantum yields for the formation of the substitution products increased with decreasing oxidation potentials of group 14 organometallic compounds. A key step for the photoreactions is the reaction of radical anions of d...

The photoreaction of a styrene/4-tributylstannylmethyl styrene (4:1) copolymer with di- and tetra-cyanoaromatic compounds in benzene-acetonitrile (1:1) gave polymers having cyanoaromatic functions in the side chain. These polymers were soluble in benzene and served as effective and recoverable sensitizers for three different types of photoinduced electron-transfer mediated organic photoreactions.

The 9,10-dicyanoanthracene (DCA)-sensitized photooxygenation of Ar 2 C=CH(CH 2 ) n CH=CAr 2 in acetonitrile was studied. When Ar = 4-CH 3 OC 6 H 4 , n = 3 and 4, bicyclic peroxides were obtained via 1,4-radical cations that are generated by intramolecular interaction between two ethenyl moieties of the alkadienes.

The reaction of cyclopentadienyl anions with Fe(CO)5 in the presence of acyl chlorides or carboxylic anhydrides gave cyclic acyliron complexes [η5-C5H4C(OCOR)=C(OCOR)CO]Fe(CO)2 via triple carbonylation of the anions and a double acylation. The structure of [η5-C5H4C(OCOCH2CH3)=C(OCOCH2CH3)CO]Fe(CO)2 thus obtained was confirmed by the X-ray analysis. Diastereomers of indenyl derivative [η5-C9H6C(OCOCH2CH3)=C(OCOCH2CH3)CO]Fe(CO)(P(OCH3)3) were prepared by substitution of CO ligand with trimethyl phosphite and the structure of the diastereomers were characterized by NMR spectroscopy using 2D technique. Treatment of cycloheptatrienyl anion with Fe(CO)5 and acyl chloride resulted in double carbonylation to give [η5-C7H6C(OCOR)=C(OCOR)]Fe(CO)2. The mechanism of the reaction is proposed.

Synthetic routes were established for amphiphilic compounds containing (η4-diene) Fe (CO) 3 as a lipophilic group and ammonium or sulfonium group as a hydrophilic group from 2, 4-hexadienoic acid and Fe (CO) 5 as starting materials. The ammonium salt, [CH3CH=CHCH=CHCO2 C6H4N+Me3] Fe (CO) 3I- (3) and sulfonium salt [CH3CH=CHCH=CHCO2C6H4S+Me2] Fe (CO) 3 MeSO4- (7) thus obtained were found soluble in water and polar organic solvents and stable in solvents.Reaction of (3) and (7) with amines in water-acetonitrile solution led to the conversion of the ester group to an amide group in good yield. The reaction of (3) with octylamine was depended on the water/acetonitrile ratio of the solvent. The yield of amide was maximum at a water/acetonitrile ratio of 3. Equilibrium between the ammonium salt and its free amine would appear to be the cause for the solvent effects. However, amide yield in the reaction of (7) with ocatylamine was virtually constant regardless of the solvent ratio.

Diastereomeric (η 4 -N-substituted-2,4-hexadienamide)Fe(CO) 3 complexes having chiral amide groups are separated and characterized. Among the complexes, the amide complexes derived from (3R)- and (3S)-3-amino-hexahydro-2H-azepin-2-one are the most easily separated by fractional crystallization and column chromatography.

α-Bromooximes such as α-bromoacetophenone oxime and ethyl 3-bromo-2-(hydroxyimino)propanoate react with enamines to give 5,6-dihydro-4H-1,2-oxazines in good yields. Dihydro-1,2-oxazine derivatives are also obtained by the reaction of α-bromooximes with vinyl ethers and silyl enol ethers in the presence of Na2CO3. Dihydro-1,2-oxazines can be converted into pyrrole derivatives via reductive deoxygenation by treating with Fe3(CO)12 in moderate to excellent yields. Iron carbonyl complexes other than Fe3(CO)12 are also effective for the pyrrole-forming reaction. The efficiency of the complexes for this reaction decreases in the order: Fe3(CO)12>>Et3NH[HFe3(CO)11]>Fe2(CO)9>>Fe(CO)5. Both of the dihydro-1,2-oxazine- and pyrrole-forming reactions can be carried out in a single flask, giving pyrrole derivatives in good yields.

Aromatic aldehydes react with Fe3(CO)12 in refluxing benzene ultimately to give arylmethyl alcohols and 1,2-diaryl-1,2-ethanedione in a 1:1 ratio. In some cases, small amounts of 2,4,5-triaryl-1,3-dioxolanes are formed as minor products. Dinuclear iron complex (1,2-diphenyl-1,2-ethanedioxido)Fe2(CO)7 has been isolated as an intermediate in the reaction of benzaldehyde with Fe3(CO)12. The mechanism of this redox reaction of aromatic aldehydes are discussed on the basis of the kinetic study of the reaction and also of the reactivity of the isolated dinuclear iron complex.

Irradiation of 1-aryl-2,2-dicyanoethenes and tetraalkylstannanes in propionitrile in the presence of phenanthrene afforded regioselectively 1-alkyl-1-aryl-2,2-dicyanoethanes in good yields.

(η3-1- and 2-Trimethylsiloxyallyl)Fe(CO)2NO complexes were prepared by the reaction of the corresponding siloxyallylic halides with Bu4N[Fe(CO)3NO]. These complexes reacted with both of carbon nucleophiles and carbon electrophiles preferentially at the less hindered sites of the allylic ligands. In these reactions, (η3-1-trimethylsiloxyallyl)Fe(CO)2NO complexes served as synthetically equivalent synthons for both of β-acyl carbocations and j8-acyl carbanions and (η3-2-trimethylsiloxyallyl)Fe(CO)2NO complexes as both of α-acyl carbocations and α-acyl carbanions. The stereochemical courses of the reactions are described.

Alkenylidenecyclopropanes have been prepared in a stereospecific manner by the reaction of 1,1-disubstituted 2,2-dibromocyclopropanes with sodium hydroxide under phase-transfer conditions in the presence of alkenes.

The 9,10-dicynoanthracene (DCA)-sensitized photoreaction of 1,2-diarylcylopropanes 1a-d in nitrogen oxide (NO)-saturated CH 3 Cn afforded 3,5-diaryl-2-isoxazolines 2a-d in excellent yiels. The reaction of 1a-d with NOBF 4 or with a mixture of NO and O 2 in CH 3 CN also afforded 2a-d or 2a-b. These reactions proceed via the attack of NO on the radical cation of 1 which is formed by electron transfer from 1 to 1 DCA . or NO +

2′-Deoxy-5-fluorouridine (5-FUdR) derivatives having various types of sulfur-containing substituents at the 5′-O-position were synthesized and their γ-radiolyses were studied in aqueous solutions. The γ-radiolysis of compounds having 1,3-dithiol-2-yl and 1,3-dithian-2-yl substituents at the 5′-O-position efficiently gave 5-FUdR, specifically via the attack of hydroxyl radical. On the other hand, the γ-radiolysis of a compound having a sulfonylmethyl substituent at the 5′-O-position gave less efficiently 5-FUdR, specifically via the attack of the hydrated electron. The mechanistic features of these reactions are discussed.

The benzophenone-sensitized intramolecular (2π + 2π) photocycloaddition of bis(4-vinylphenyl-methyl)sulfide and selenide in benzene afforded cyclobutacyclophanes containing sulfur and selenium in good yields. However, the photoreaction of bis(4-vinylphenylmethyl)telluride under similar conditions did not give the corresponding cyclophane compound.

The oxidation of (diphenylethenylidene) cyclopropanes and (dialkylethenylidene) cyclopropanes with m-chloroperbenzoic acid gave respectively 2-(diphenylethylidene) cyclobutan-1-ones and cyclopropyl keto esters with high selectivity.

Seventeen compounds having a variety of substituents at the 3- and 5′-positions of 2′-deoxy-5-fluorouridine (5-FUdR) and 5-fluorouridine (5-FUR) were synthesized, and their γ-radiolysis in aqueous solutions were studied. The compounds having thioureido (RNHCSNH, R H, PhCH2, acyl) and thiocarbonylamino (XCSNH, X PhCH2S, PhO) groups at the 3-position of 5-FUdR were efficiently cleaved to give 5-FUdR with high G values upon γ-irradiation of their aqueous solutions. The active species for these cleavage reactions were hydrated electron (e− aq), H• and HO•. However, the compounds having a dimethylsulfoxyimino group at 3-position of 5-FUdR and 5-FUR afforded 5-FUdR and 5-FUR only under the radiolysis conditions where e− aq becomes a principal active species. The compound having a 2-benzoylthiazoylthiocarbonylamino group at the 3-position of 5-FUdR showed the highest reactivity toward HO.. The mechanisms of these γ-radiolysis reactions are discussed. The examination of anticellular activities of γ-irradiated compounds having a thiocarbonylamino group at the 3-position of 5-FUdR toward murine Sarcoma 180 cells revealed that these compounds may be utilized as a candidate for a radiation-induced drug (RID).

Irradiation of benzene solutions containing 9-cyanophenanthrene and electron-deficient arylalkenes such as E- and Z-methyl cinnamates afforded (2π + 2π) photocycloadducts between the two electron-deficient components in a stereospecific manner.

Solvent and additive effects on the photoreaction of 1,4-dicyanonaphthalene, (1,4-DCN) with allylic silanes (1a–c) have been investigated. Irradiation of acetonitrile solutions containing 1,4-DCN and 1a–c in the presence of NaOMe selectively afforded the substitution products 1-(2′-alkenyl)-4-cyanonaphthalenes (2a–c) in high yields. The photoreaction of1,4-DCN with 1a–c in the presence of pyrene in CH3CN-MeOH (4:1) selectively afforded the addition products 1-(2′-alkenyl)-1,4-dicyano-1,2-dihydronaphthalenes (3a–c, 3c′) in high yields. The photoreaction of 1,4-DCN with 1a-c in the presence of phenanthrene in CH3CN-MeOH (4:1) afforded the tricyclic compounds 3,6-dicyano-4,5-benzotricyclo-[4.2.1.03,8]-4-nonenes (4a–c, 4c′) and 5b (the regioisomer of 4b), which were produced via an intra-molecular (3π+2π) photocycloaddition of 3a–c and 2c′. The mechanistic features of these photoreaction are discussed.

The 9,10-dicyanoanthracene (DCA)-sensitized photooxygenation of Ar 2 C=CH(CH 2 ) n CH=CAr 2 in acetonitrile was studied. When Ar = 4-CH 3 OC 6 H 4 , n = 3 and 4, bicyclic peroxides were obtained via 1,4-radical cations that are generated by intramolecular interaction between two ethenyl moieties of the alkadienes.

The reaction of cyclopentadienyl anions with Fe(CO)5 in the presence of acyl chlorides or carboxylic anhydrides gave cyclic acyliron complexes [η5-C5H4C(OCOR)=C(OCOR)CO]Fe(CO)2 via triple carbonylation of the anions and a double acylation. The structure of [η5-C5H4C(OCOCH2CH3)=C(OCOCH2CH3)CO]Fe(CO)2 thus obtained was confirmed by the X-ray analysis. Diastereomers of indenyl derivative [η5-C9H6C(OCOCH2CH3)=C(OCOCH2CH3)CO]Fe(CO)(P(OCH3)3) were prepared by substitution of CO ligand with trimethyl phosphite and the structure of the diastereomers were characterized by NMR spectroscopy using 2D technique. Treatment of cycloheptatrienyl anion with Fe(CO)5 and acyl chloride resulted in double carbonylation to give [η5-C7H6C(OCOR)=C(OCOR)]Fe(CO)2. The mechanism of the reaction is proposed.

This review article deals with addition and cycloaddition reactions of organic compounds via photoinduced electron transfer. Various reactive species such as exciplex, triplex, radical ion pair and free radical ions are generated via photoinduced electron transfer reactions. These reactive species have their characteristic reactivities and discrimination among these species provides selective photoreactions. The solvent and salt effects and also the effects of electron transfer sensitizers on photoinduced electron transfer reactions can be applied to the selective generation of the reactive species. Examples and mechanistic features of photoaddition and photocycloaddition reactions that proceed via the following steps are given: reactions of radical cations with nucleophiles; reactions of radical anions with electrophiles; reactions of radical cations and radical anions with neutral radicals; radical-radical coupling reactions; addition and cycloaddition reactions via triplexes; three-component addition reactions.

The calix[6]arene 1 bearing six trioxadecyl groups on the phenolic oxygens served as an effective catalyst for the oxidation of alkenes, alkynes, and alcohols with KMnO4 in CH2Cl2. The reaction of ...