Aziridination of C60 with simple amides and catalytic rearrangement of the aziridinofullerenes to azafulleroids.

The selective formation of aziridinofullerene and azafulleroid, which are isomers of the fullerene derivatives-introduced N(1) unit, is achieved. The ionic aziridination is a very convenient and risk-free procedure compared with the conventional method with azides as nitrogen sources, and gives aziridinofullerenes from various readily available amides (carbamates, ureas, carboxamides, and phosphamides). For example, benzyl carbamate was chlorinated by tert-butyl hypochlorite (tert-BuOCl) and then reacted with C(60) in the presence of base to give N-benzyloxycarbonyl aziridinofullerene exclusively and without formation of its isomer, an azafulleroid. The reaction enabled the synthesis of functional fullerene derivatives having a trialkoxysilyl group and an amino acid moiety. Azafulleroids were obtained through the rearrangement of corresponding aziridinofullerenes by using the combination of a chloramine catalyst and MS4A. Among other chloramines used, chloramine B (CB) showed superior ability as a catalyst in the rearrangement. It was found that MS4A functions as a Lewis acid in the reaction.

Asymmetric recognition and sequential ring opening of 2-substituted-N-nosylaziridines with (DHQD)2AQN and TMSNu.

A new method for asymmetric ring opening of terminal aziridines using a chiral amine, (DHQD)(2)AQN, is described; the reaction is based on the asymmetric recognition of aziridines using (DHQD)(2)AQN and on sequential ring opening using TMSNu.

The ionic introduction of an N1 unit to C60 and a unique rearrangement of aziridinofullerene.

A new chloramine-based aziridination of C60 and unique rearrangement of aziridinofullerene to azafulleroid is described. The ionic introduction of an N1 unit to C60 via an addition-cyclization mechanism was first achieved under mild conditions; the combination of chloramine and MS4A resulted in the promising rearrangement of aziridinofullerene to azafulleroid, and the isomerization could be performed catalytically.

Catalytic aziridination of electron-deficient olefins with an N-chloro-N-sodio carbamate and application of this novel method to asymmetric synthesis.

A new method for the aziridination of electron-deficient olefins using an N-chloro-N-sodio carbamate is described; the reaction was promoted by phase-transfer catalysis (solid-liquid) and afforded aziridines from alpha,beta-unsaturated ketones, esters, sulfones and amides.

Direct synthesis of oxazolines from olefins and amides using t-BuOI.

A new and simple method for the synthesis of oxazolines from readily accessible olefins and amides using tert-butyl hypoiodite is described; aromatic/aliphatic olefins and amides can be used in the reaction to give a variety of oxazolines.

Unprecedented CO2-promoted aminochlorination of olefins with Chloramine-T.

A new synthetic procedure for the aminochlorination of olefins for the synthesis of vicinal chloroamine derivatives using a combination of Chloramine-T and carbon dioxide is described. The method can be applied to a variety of olefins, including an electron-sufficient olefin and a conjugated diene.

Practical and convenient synthesis of N-heterocycles: stereoselective cyclization of N-alkenylamides with t-BuOI under neutral conditions.

[Structure: see text] tert-Butyl hypoiodite (t-BuOI) was found to be a powerful reagent for the cyclization of N-alkenylamides leading to a variety of N-heterocycles under extremely mild conditions. When N-alkenylsulfonamides were employed in the reaction, three- to six-membered saturated N-heterocycles were obtained in good to excellent yields with complete stereoselectivity. The method was applicable to the cyclization of alkenylbenzamide derivatives to afford N-, O- or N-, S-heterocycles.

1,6-Stannatropic strategy: effective generation and cyclization of 1,5-dipoles from o-stannylmethylated thioanilides or phenyl isothiocyanates.

[reaction: see text] A new method for the generation of 1,5-dipoles from o-stannylmethylated thioanilides via 1,6-stannatropy under neutral conditions was developed. Cyclization of the 1,5-dipoles afforded indole derivatives effectively. The strategy has potential for application to the generation of alternative 1,5-dipoles from o-stannylmethylated aryl isothiocyanates leading to indole derivatives having a stannylthio group that was readily converted to other functional groups.

Novel aziridination of olefins: direct synthesis from sulfonamides using t-BuOI.

tert-Butyl hypoiodite (t-BuOI) was found to be a powerful reagent for synthesis of aziridines from olefins and sulfonamides. The aziridination of olefins was achieved by using sulfonamides with t-BuOI. Our preliminary findings represent the example of metal-free aziridination of olefins with readily accessible sulfonamides as a nitrogen source.

Unprecedented 1,4-stannatropy: effective generation of azomethine ylides as nitrile ylide equivalents from N-(stannylmethyl)thioamides.

Generation and cycloaddition of less- or non-stabilized azomethine ylides, or nitrile ylide equivalents, via unprecedented 1,4-stannatropy of N-(tributylstannylmethyl)thioamides were achieved. The reactions with dipolarophiles, such as electron-deficient alkenes and alkynes, afforded corresponding pyrrolidine and pyrrole derivatives effectively.

Lewis base catalyzed ring opening of aziridines with silylated nucleophiles.

The ring opening of N-tosylaziridines with trimethylsilylated nucleophiles, catalyzed by N,N,N',N'-tetramethylethylenediamine, led to the production of beta-functionalized sulfonamides in good to excellent yields with high regioselectivity. [reaction: see text]

An anionic strategy for three- and four-component coupling reactions leading to ketone frameworks based on vinylogous conversion of dilithio ketone alpha,beta-dianions.

[reaction: see text] Ketone alpha,delta-dianions are generated by vinylogous extension of ketone alpha,beta-dianions with alkenes such as vinylarenes, vinylsilanes, and vinyl sulfides, which then undergo reactions at the delta and alpha positions with different electrophiles, creating ketone frameworks. This work represents a cascade-type anion method that achieved three- and four-carbon component assembly reactions leading to ketones.

Unique ionic iodine atom transfer cyclization: a new route to iodomethylated pyrrolidine derivatives from gamma-iodoolefin and chloramine-T.

[reaction: see text] Pyrrolidines and bicyclic pyrrolidine derivatives can effectively be synthesized from gamma-iodoolefins using commercially available chloramine-T (CT) as a nitrogen source. The cyclization proceeds with high stereoselectivity via a cyclic iodonium intermediate.

Generation and cycloaddition of polymer-supported azomethine ylide via a 1,2-silatropic shift of alpha-silylimines: traceless synthesis of pyrrolidine derivatives.

The 1,3-dipolar cycloaddition of polymer-supported azomethine ylides to dipolarophiles gave pyrrolidine derivatives in good yields. The azomethine ylides were generated from resin-bound alpha-silylimines via a 1,2-silatropic shift. The features of this method are not only a traceless synthesis but also a unique solid-phase route to pyrrolidines with extensive diversity. [reaction: see text]

exo- and enantioselective cycloaddition of azomethine ylides generated from N-alkylidene glycine esters using chiral phosphine-copper complexes.

High diastereo- and enantioselectivities were obtained for the asymmetric 1,3-dipolar cycloaddition of azomethine ylides generated from N-alkylideneglycine esters with dipolarophiles using chiral phosphine-copper complexes as catalysts. Whereas the cycloaddition of azomethine ylides catalyzed by metal salts generally afforded endo-adducts as the predominant product, the present method is the first example of an exo-selective cycloaddition. [reaction: see text]

Group Transfer Carbonylations: Photoinduced Alkylative Carbonylation of Alkenes Accompanied by Phenylselenenyl Transfer.

The photolysis of methyl alpha-(phenylseleno)acetate (1b) and related compounds in the presence of an alkene and CO leads to acyl selenides 2 via group transfer carbonylation. The mechanism of this three-component coupling reaction involves the addition of a (methoxycarbonyl)methyl radical to an alkene, the trapping of the produced alkyl free radical by CO, and termination of the reaction by a phenylselenenyl group transfer from the starting material.

Model Studies of TTQ-Containing Amine Dehydrogenases.

The reactions of a TTQ model compound [1, 3-methyl-4-(3'-methylindol-2'-yl)indole-6,7-dione] with several amines have been investigated in organic media to obtain mechanistic information on the action of quinoprotein methylamine and aromatic amine dehydrogenases. It has been found that compound 1 acts as an efficient catalyst for the autorecycling oxidation of benzylamine by molecular oxygen in CH(3)OH. In order to evaluate the oxidation mechanism of amines by 1, the product analyses and kinetic studies have been carried out under anaerobic conditions. In the first stage of the reaction of 1 with amines, 1 is converted into an iminoquinone-type adduct (so-called substrateimine), which was isolated and characterized by using cyclopropylamine as a substrate. The observed NOE of the isolated product indicates clearly that the addition position of the amine is C-6 of the quinone. The molecular orbital calculations suggest that the thermodynamic stability of the carbinolamine intermediate is a major factor to determine such regioselectivity; the C-6 carbinolamine is more stable than the C-7 counterpart by 2.9 kcal/mol. The reactivity of several primary amines and the electronic effect of the p-substituents of benzylamine derivatives in the iminoquinone formation suggest that the addition step of the amine to the quinone is rate-determining. When amines having an acidic alpha-proton such as benzylamine derivatives are employed as substrates, formation of the iminoquinone adduct was followed by rearrangement to the productimine. The kinetic analysis has revealed that this rearrangement consists of noncatalyzed and general base-catalyzed processes. Large kinetic isotope effects of 7.8 and 9.2 were observed for both the noncatalyzed and general base-catalyzed processes, respectively, since these steps involve a proton abstraction from the alpha-position of the substrate. In the reaction with benzhydrylamine, the product imine was isolated quantitatively and well characterized by several spectroscopic data. In the case of benzylamine, the product imine is further converted into the aminophenol derivative by the imine exchange reaction with excess benzylamine. These results indicate clearly that the amine oxidation by compound 1 proceeds via a transamination mechanism as suggested for the enzymatic oxidation of amines by TTQ cofactor.

Active Site Models for Galactose Oxidase. Electronic Effect of the Thioether Group in the Novel Organic Cofactor.

The electronic effect of the thioether linkage between Tyr 272 and Cys 228 (the novel organic cofactor) of galactose oxidase has been examined by using model compounds, 2-(methylthio)-p-cresol (1H), 2-(methylthio)-4,6-dimethylphenol (2H), and 2-(methylthio)-4-methyl-6-[[bis[2-(2-pyridyl)ethyl]amino]methyl]phenol (3H), the physicochemical properties of which are compared to those of 2-[[bis[2-(2-pyridyl)ethyl]amino]methyl]-4-methylphenol (4H) and p-cresol (5H). (1)H NMR and electrochemical studies indicate that the methylthio group has essentially an electron-donating nature. On the other hand, the lower pK(a) values of 1H and 2H as compared to that of 5H suggest that the methylthio group also has a 2ppi-3dpi electron conjugative effect, stabilizing the negative charge on the phenolate oxygen. Furthermore, the electron-sharing conjugative effect of the substituent in the radical state has been clearly demonstrated by ESR studies and semiempirical molecular orbital calculations. Dimer copper(II) complexes [Cu(II)(2)(3(-)())(2)](PF(6))(2) (7) and [Cu(II)(2)(4(-)())(2)](PF(6))(2) (8) were prepared, and the crystal structures were determined by the X-ray diffraction method. Electrochemical analyses of the monomeric species [Cu(II)(3(-)())(py)](PF(6)) (9) and [Cu(II)(4(-)())(py)](PF(6)) (10) generated in situ by adding an external ligand such as pyridine (py) reveal that the methylthio substituent in the copper complex shows electronic effects similar to those of the free ligand stabilizing the phenoxyl radical state of the cofactor moiety in the Cu(II) complex.

Novel Asymmetric and Stereospecific Aziridination of Alkenes with a Chiral Nitridomanganese Complex.

The addition of pyridine N-oxide is necessary to obtain high enantioselectivities in the asymmetric aziridination of styrene derivatives through transfer of a nitrogen atom from chiral, toluenesulfonic anhydride activated nitridomanganese complex 1 [Eq. (a)]. Remarkably, high stereospecificity was observed in all the aziridinations of trans- and cis-1,2-disubstituted alkenes. R1 =H, Me, nPr, iPr; R2 =H, Me; Ts=p-toluenesulfonyl.