Reactions of α-Phosphoryl-α-haloacetaldehydes with Difunctional Nucleophiles

Reactions of phosphorylated α-haloacetaldehydes with difunctional nitrogen-, oxygen-, and sulfur-containing nucleophiles were performed with a view to synthesize C-phosphorylated heterocyclic compounds.__________Translated from Zhurnal Organicheskoi Khimii, Vol. 41, No. 4, 2005, pp. 520–523.Original Russian Text Copyright © 2005 by Asadov, Burangulova, Guseinov.     

2,3,5,6-Tetra(pyrazin-2-yl)pyrazine: a novel bis-bidentate, bis-tridentate chelator

Novel 10-nitrogen ligand, 2,3,5,6-tetra(pyrazin-2-yl)pyrazine, has been synthesized in four steps. This compound shows different conformations and the crystal structure of one of them has been established. This structure is sustained by non-classical H-bonds and π···π interactions among heteroaromatic rings.     

2(5H)-呋喃酮与含氮亲核试剂反应研究进展

2(5H)-呋喃酮作为一种α,β-不饱和环丁内酯,可发生多种反应,特别是其不饱和碳碳双键上连有卤素时,2(5H)-呋喃酮的高反应性使其被广泛应用于有机合成.按照反应后五元环内酯产物上取代基位置的不同,综述了2(5H)-呋喃酮与含氮亲核试剂通过Michael加成、串联的Michael加成-消除、偶极环加成和钯催化耦合等反应合成β-取代、α,β-取代和γ-取代环状衍生物在近十几年的研究进展.     

Reactions of 4-methyl(chloro)sulfonyl-2,3,5,6-tetrabromopyridines with nucleophilic reagents

The MeSO₂ group is replaced in the reaction of 4-methylsulfonyltetrabromopyridine with small nucleophiles, whereas the Br atom in the 2 position is replaced in the reaction with bulky nucleophiles. Depending on the temperature conditions and the ratio of the reacting substances, 4-chlorosulfonyltetrabromopyridine reacts with primary amines to give either the corresponding amides or amines. It was established that the corresponding amines are formed when tetrabromopyridinesulfonic acid -hydroxyalkylamides are heated with triethylamine.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 937–942, July, 1979.     

Reactions of Alicyclic Epoxy Compounds with Nitrogen-Containing Nucleophiles

The review considers reactions of alicyclic epoxy compounds and their analogs with nitrogen-containing nucleophilic reagents, such as amines, azides, hydrazines, etc., biological aspects of these reactions, and properties of amino alcohols which are practically important organic products and synthons. Reaction mechanisms, including radical and radical ion reaction paths, the results of quantum-chemical studies, stereo- and regioselectivity aspects, and activation of epoxy substrates with achiral and chiral catalysts are discussed. The formation of nitrogen-containing heterocyclic systems via opening of the oxirane ring is described.     

Synthesis of Hexakis(vinylthio)benzene

Exhaustive nucleophilic replacement of fluorine atoms in hexafluorobenzene by vinylthio groups was accomplished by the action of sodium ethenethiolate in dimethylformamide-liquid ammonia at -5 to 0°C.     

Alkyl 2,2,2-Trifluoroethanesulfonates (Tresylates): Elimination-Addition vs Bimolecular Nucleophilic Substitution in Reactions with Nucleophiles in Aqueous Media(1)

Alkyl 2,2,2-trifluoroethanesulfonate esters (tresylates), ROSO(2)CH(2)CF(3), react with aqueous base (pH >/= 9) to give the (alkoxysulfonyl)acetic acid, ROSO(2)CH(2)COOH; with the further addition of either a primary or secondary amine or of an alkanethiol, the product is the either the corresponding amide, ROSO(2)CH(2)C(O)NR(1)R(2), or a mixture in which the ketene dithioacetal, ROSO(2)CH=C(SR(1))(2), or the thioorthoester, ROSO(2)CH(2)C(SR(1))(3), may predominate. Kinetic and product studies are consistent with the following: (a) the reaction of tresylates with water is the normal sulfonic ester hydrolysis and (b) reaction with hydroxide is an (E1cB)(rev) process with loss of HF to yield the alkyl 2,2-difluoroethenesulfonate, ROSO(2)CH=CF(2), which rapidly yields the observed products. Benzyl 2,2,2-trifluoroethyl sulfone reacts analogously. The relationship between these observation with small molecules and those of earlier workers with tresyl agarose is discussed.     

Reactions of Chlorosulfanyl Derivatives of Cyclobutanones with Different Nucleophiles

The reactions of 3‐chloro‐3‐(chlorosulfanyl)‐2,2,4,4‐tetramethylcyclobutan‐1‐one ( 2 ) with N, O, S, and P nucleophiles occur by substitution of Cl at the S‐atom. Whereas, in the cases of secondary amines, alkanols, phenols, thiols, thiophenols, and di‐ and trialkyl phosphates, the initially formed substitution products were obtained, the corresponding products with allyl and propargyl alcohols undergo a [2,3]‐sigmatropic rearrangement to give allyl and allenyl sulfoxides, respectively. Analogous substitution reactions were observed when 3‐chloro‐3‐(chlorodisulfanyl)‐2,2,4,4‐tetramethylcyclobutan‐1‐one ( 3 ) was treated with N, O, and S nucleophiles. The reaction of 3 with Et₃P led to an unexpected product via cleavage of the S? S bond (cf. Scheme 13). In the reactions of 2 with primary amines and H₂O, the substitution products react further via elimination of HCl to yield the corresponding thiocarbonyl S‐imides and the thiocarbonyl S‐oxide, respectively. Whereas the latter could be isolated, the former were not stable but could be intercepted by MeOH (Scheme 4) or adamantanethione (Scheme 5). The structures of some of the substitution products were established by X‐ray crystallography.     

Reactions of Methyl 4-Aminofurazan-3-carboximidate with Nitrogen-Containing Nucleophiles

Methyl 4-aminofurazan-3-carboximidate reacts with aromatic amines and hydrazines to give the corresponding amidines and amidrazones. The reaction of the title compound with o-phenylenediamine yields 3-amino-4-(2-benzimidazolyl)furazan, and with acylhydrazines N²-acyl-4-aminofurazan-3-carbohydrazides are formed. The latter undergo thermal intramolecular cyclization with formation of 3-amino-4-(1,2,4-triazol-3-yl)furazan derivatives containing various substituents in position 5 of the triazole ring.     

Reactions of Nucleophiles with Nitroarenes: Multifacial and Versatile Electrophiles

In this overview, it is shown that there are many initial reactions between nitroarenes and nucleophiles: addition to the electron‐deficient ring at positions occupied by halogen and hydrogen atoms, addition to the nitro group, single‐electron transfer (SET), and other types of initial reactions. The resulting intermediates react further in a variety of ways to form products of nucleophilic substitution of a halogen atom (S_NAr), a hydrogen atom (S_NArH), and others. Many variants of these processes are briefly discussed, particularly in relation of rates of the initial reactions and further transformations.     

Rhodium-catalyzed Asymmetric Ring-opening Reactions of N-Boc-azabenzonorbornadiene with N-Substituted Piperazine Nucleophiles

Asymmetric ring‐opening reactions of N‐Boc‐azabenzonorbornadiene with N‐substituted piperazine nucleophiles in the presence of 5 mol% of [Rh(COD)Cl]₂ and 10 mol% of chiral ligand, (R,S)‐PPF‐P‐t‐Bu₂, gave the corresponding 1,2‐diamine product in moderate to excellent yields (up to 95%) with reasonable enantiomeric excesses (up to 70% ee). The results showed that the nature of ligands had significant influence on the yields and the enantiomeric excesses.     

The Synthesis of Sulfinylphthalimides and their Reactions with Some Nucleophiles in Dioxane

Abstract

In this study, some N-(p-substituted-arylsulfinyl)phthalimides (1a–1e) were synthesized. The synthesized compounds were examined with respect to their substitution reactions with sodium ethoxide, sodium methoxide, methylamine, and t-butylamine in dioxane. The substituent effect was investigated at 30.0 ± 0.1 °C. The activation entropy was also studied, and negative ΔS^≠ values were obtained. Configuration inversions were observed in the substitution reactions. This result is in conformity with the S_N2 mechanism.

[Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements for the following free supplemental resource: Characterization of -(p-Substituted-arylsulfinyl)phthalimides 1a–b.]     

A Stereospecific Synthesis of Dialkyl(Aryl)-2-Nitroeth-1-Enylphosphonates and their Reactions with Non-Carbon Nucleophiles

Abstract

Dialkyl l-alkyl(aryl)-2-nitroen-l-enylphosphonates (1) are the important intermediate for the synthesis of functionalized phosphonic acids owing to the presence of reactive alkene and nitrogroups. It was expected that nucleophilic addition and subsequent reduction would result 2-aminólkyl phosphonic acid derivatives. On the other hand, conversion of nitrogroup into silylnitronate as reactive 1,3-dipole provides new synthetic route to phosphoryl isoxazoles. Compounds 1 were prepared by treatment of dialkyl 1 -alkyl(aryl) -1 -hydroxy-2-nitrólkylphosphonates with thionyl chloride and pyridine. The dehydration process underwent stereospecifically providing exclusive E-ismers. An E2 reaction mechanism is suggested.