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.

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.

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.

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.

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.

Ring opening and expansion of aziridines in a silica-water reaction medium.

Ring-opening reactions of N-tosylaziridines with water-soluble nucleophiles proceeded in a silica-water reaction medium. The system is applicable to a ring expansion of an aziridine with potassium thiocyanate, leading to a thiazolidine derivative.

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.

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.

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.

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.

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]

Novel synthesis of gem-dichloroaziridines from imines via the KF/Al2O3-promoted generation of dichlorocarbene from chloroform.

KF/Al(2)O(3) was found to be an efficient base for the reaction of imines with chloroform in acetonitrile to give gem-dichloroaziridines 2 in moderate to high yields. The KF/Al(2)O(3)-promoted dichloroaziridination can be carried out with simple workup, tolerates a variety of functional groups present in the imines, and proceeds smoothly with a smaller amount of carbene source.

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.

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]

Cyclizative radical carbonylations of azaenynes by TTMSS and hexanethiol leading to alpha-silyl- and thiomethylene lactams. Insights into the E/Z stereoselectivities.

Free-radical mediated cyclizative carbonylations of azaenynes were carried out using TTMSS as a radical mediator to compare the efficiency and the stereochemistry with those using tributyltin hydride. Using a substrate concentration of 0.1 M, the reactions gave good yields of alpha-silylmethylene lactams having four to seven-membered rings. The observed E-diastereoselectivity of the resulting vinylsilane moiety is in sharp contrast to the Z-selectivity observed during the analogous carbonylation using tributyltin hydride. When hexanethiol was used as the radical mediator, alpha-thiomethylene lactams were formed with E-favoring stereoselectivity again. Ab initio and DFT molecular orbital calculations on the stability of E and Z products were carried out for a set of five-membered methylene lactams bearing SnH3, SiH3, and SMe groups. The distinct thermodynamic preference for the Z-isomer was only predicted for the Sn-bearing lactam. A steric effect due to the bulky (TMS)3Si group is proposed for the E-selectivity observed in the TTMSS-mediated reaction.

1,4-silatropy of S-alpha-silylbenzyl thioesters: a convenient route to silyl enol and dienol ethers accompanied by C-C bond formation via thiocarbonyl ylides.

A novel convenient method for the generation of thiocarbonyl ylides from readily accessible starting materials and the first synthetic application of in situ generated ylides in the synthesis of silyl enol and dienol ethers, accompanied by C-C bond formation, is described. Under completely neutral conditions without any catalyst or additive, thermal reactions of S-alpha-silylbenzyl thioesters in sealed tubes at 180 degrees C provided silyl enol and dienol ethers in good to excellent yields with high stereoselectivities. This procedure consists of a multistep reaction in a one-pot process, i.e., 1,4-silatropy of S-alpha-silylbenzyl thioesters to give thiocarbonyl ylides, 1,3-electrocyclization of the ylides to give thiiranes, and the extrusion of sulfur from thiiranes to give silyl enol and dienol ethers.