Unexplored nucleophilic ring opening of aziridines

The reactivity of dianions of carboxylic acids towards aziridines has been studied. Although, a similar reactivity to that of enolates from ketones, esters or amides has been observed, the method directly yields γ-aminoacids in one step. The method is complementary of previous results of enenediolate reactivity with other electrophiles. A comparative study with the reactivity of this enediolates with epoxides is included.     

Fluorine-containing quinazolines annulated at the pyrimidine ring

Fluorine-containing quinazolines annulated at the sides [a] and [c] were synthesized by the reaction of 2- and 4-hydrazino-substituted quinazolines with aldehydes and subsequent oxidative cyclization. Annulation at the side [b] was performed by alkylation of 2-alkylthio-4(3H)-quinazolinones with bromoethanol and ipso-substitution of the alkylthio group.

     

A telluride-triggered nucleophilic ring opening of monoactivated cyclopropanes

[reaction: see text] Acylcyclopropanemethanol tosylates undergo rapid ring opening at room temperature by the action of lithium telluride to produce the enolate of a homoallylic ketone. The enolate can be protonated to yield the corresponding ketone or treated with benzaldehyde to give the aldol product with good syn or anti diastereoselectivity depending on the conditions.     

Reactions of pyrylium salts with nucleophilic agents

The reaction of -unsubstituted pyrylium salts with alkali-metal cyanides gives cyano- and carboxy-substituted pyrans and pyrylium salts, while the reaction with sodium sulfide gives dipyranyl sulfides. A phthalimide derivative of pyran is obtained from 2,6-diphenylpyrylium perchlorate and potassium phthalimide, while pyrylium cations react with zinc to give the corresponding dipyranyls.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1313–1316, October, 1972.     

Action of photoreactivating light on pyrimidine heteroadduct in bacteria

Abstract— In stationary-phase Escherichia coli B/r, photoreactivation (PR) at 313 nm of ultraviolet (u.v.) killing is inefficient compared with PR at 405 nm, and can be explained solely by photoenzymatic reversal of pyrimidine dimers. In Staphylococcus epidermidis, PR shows a maximum at 313 nm, suggesting that this organism shows the Type III PR proposed by Jagger et al.[5] for Streptomyces strains. Reversal of pyrimidine dimers is not sufficient to explain this PR. The mechanism of Type III PR remains unknown. With both S. epidermidis and E. coli B/r, the amount of uracil–thymine heteroadduct in DNA hydrolysates decreases if the cells are given a post-u.v. treatment at 313 nm, but no decrease is observed if the post-u.v. treatment is at 405 nm. The biological significance of this adduct and of its removal is not clear. It may play a role in Type III PR.     

Reaction for nucleophilic opening of thiirane ring by thiols

Conclusions The nucleophilic opening of the thiirane ring by thiols proceeds with greater difficulty than that of the oxirane ring. Aliphatic and aromatic thiols in nonpolar solvents, using homogeneous catalysis by bases, can be unambiguously mercaptoethylated by selecting the necessary ratios of thiol compound and ethylene sulfide.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 660–662, March, 1975.     

Remote electronic effects in the rhodium-catalyzed nucleophilic ring opening of oxabenzonorbornadienes

We report the application of our rhodium-catalyzed nucleophilic ring-opening methodology to unsymmetrically arene-substituted oxabenzonorbornadienes. The regioselectivity of the ring opening was investigated using a variety of nucleophiles that led to a broad selection of dihydronaphthalene products. It was found that good to excellent regioselectivities are obtained using strongly pi-donating substituents, whereas sigma-donating and electron-withdrawing functionalities have a minimal effect. Post ring-opening manipulations of functional groups in the dihydronaphthalene products were shown to give efficient access to mono- and diamine tetrahydronaphthalene building blocks.     

Reactions of 1-arylthioniacycloalkane salts with nucleophilic agents

Depending on the structures of the salt and the nucleophilic agent, replacement of the anion of the sulfonium salt or expansion of the heteroring at the C-S bond to give substituted alkyl aryl sulfides occurs in the reaction of 1-(p-hydroxyphenyl)- and 1-(p-methoxyphenyl)thioniacyclopentane (I, III) and -thioniacyclohexane perchlorates (II, IV) in aqueous or alcohol solutions with potassium halides and potassium hydroxide. The ease of cleavage of the C-S bond as a function of the nature of the nucleophilic agent decreases in the order KOH > Cl > Br. The strength of the C-S bond of the heteroring decreases in the order II > I >IV > III. All of the heterocycles (I–IV) are stable with respect to the action of picric acid and potassium iodide, and 1-(p-hydroxyphenyl)thioniacyclohexane perchlorate (II) is stable with respect to the other investigated nucleophiles.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1032–1038, August, 1978.     

Novel route for the transformation of a pyrimidine ring using hydrazides

It has been shown from X-ray structural analytical data that the reaction of 2-ethoxycarbonylmethyl-1,4,6-trimethylpyrimidinium iodide with carboxylic acid hydrazides gives pyrazolo[1,5-a]pyrimidine derivatives and not the isomeric triazolo[4,3-a]pyridines previously reported. This novel and previously unreported rearrangement of 1,2-dialkylpyrimidinium salts occurs via recyclization of the pyrimidine ring with inclusion of a fragment of the nucleophilic reagent into the transformation product. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 262–275, February, 2006.