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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 ...

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.

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...

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...

Acyl halides adjacent to (η 4 -diene)Fe(CO) 3 group react with allyltrimethylsilanes without catalyst to give the corresponding allyl ketones in high yields.

Emission associated with exciplex between (R)-(−)- or (S)-(+)-2,2′-dimethyl-1,1-bianthryl (R-(−)-1 or S-(+)-1) and N,N-dimethylaniline (DMA) was quenched by (+) and (−)-menthyl cinnamates at room temperature. The chiral exciplexes were discriminated by the two enantiomeric quenchers that interact with the exciplexes in an enantioselective manner.

The reaction of alkenyloxiranes with Bu 4 N[Fe(CO) 3 NO] in the presence of acetyl chloride and pyridine gave [ η 3 -1-(acetoxymethyl)allyl]-Fe(CO) 2 NO complexes. These complexes reacted regio- and stereoselectively with carbon nucleophiles to give 3-substituted 4-acetoxy-1-butene derivatives.

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.

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...

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...

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 9,10-dicyanoanthracene (DCA)-sensitized photooxygenation of biphenyl derivatives in the presence of Mg(CIO4)2 in acetonitrile produces benzoic acid and its derivatives in high yields. In the absence of Mg(CIO4)2, the rates for the consumption of biphenyl derivatives decrease by a factor of 0.5-0.8, compared with those in the presence of Mg(CIO4)2. In these cases, however, both biphenyls and DCA are oxygenated to give benzoic acids and anthraquinone, respectively, indicating that the addition of Mg(CIO4)2 retards the photooxygenation of DCA. With 4-methylbiphenyl, the photooxygenation proceeds efficiently without added Mg(CIO4)2, and benzene rings and methyl groups are competitively oxygenated to give benzoic acid, 4-methylbenzoic acid, 4-phenylbenzoic acid, and 4-phenylbenzaldehyde. The addition of Mg(CIO4)2 facilitates the oxidation of benzene rings, giving benzoic acid and 4-methylbenzoic acid as major products. These photooxygenations are initiated by a one-electron transfer from biphenyls to the excited singlet DCA and proceed via the radical cations of biphenyls and the radical anion of DCA.

Apres hydrogenolyse des produits sur Pd/C, obtention des 1,2-threo-2,3-erythro-2-alkyl-1,3-diaryl-1,3-diols correspondants. Mecanisme de la photoreaction

置換複素芳香環化合物におけるπ電子密度の値を8π電子系として環内ヘテロ原子および置換基のCoulomb積分,共鳴積分の値の関数としてHuckel法により計算した。5員環化合物の場合,求電子的反応を受ける位置はα-置換体ではヘテロ原子および置換基のCoulomb積分により変化するが,β-置換体ではヘテロ原子および置換基に与える積分値によってほとんど変化せず2位である。6員環化合物の場合,求電子的反応を受ける位置はα-置換体では主として置換基のCoulomb積分により,β-置換体ではヘテロ原子および置換基に与える積分値により変化するが,γ-置換体では各積分値によらず3位である。

置換複素芳香環式化合物の各炭素原子上のπ電子密度, およびsuperdelecarizabilityの値を環内ヘテロ原子および置換基に与えるCoulomb積分の値を種々変えて,Huckel法により計算した。π電子密度およびsuperdelocarizabilityの値は, いずれも環内ヘテロ原子のCoulomb積分の絶対値の増大につれて, 一般に小さくなった。 また, 上記の反応性指数に対する置換基効果は複素芳香環の種類および環内ヘテロ原子と置換基との相対位置によって変化した。さらに, 計算によって得られた置換基効果の伝達の度合は実験結果とよく一致することが明らかになった。

置換複素芳香環化合物における最高被占軌道のエネルギーおよびπ結合次数の値を環内ヘテロ原子および置換基のCoulomb積分,共鳴積分の値の関数としてHuckel法により計算した。最高被占軌道のエネルギーは一般にヘテロ原子および置換基のCoulomb積分の絶対値が大きくなるにつれて小さくなる。最高被占軌道のエネルギーは置換基のCoulomb積分により大きな影響を受け,他の3者の効果は小さい。環内の各位置のπ結合次数は置換基のCoulomb積分,ヘテロ原子の共鳴積分の値により大きな影響を受げる。