Reactions of boryloxymethyl- and hydroxymethylphosphines with amines

Conclusions 5-(Hydroxymethyl)-2,2,5-triphenyl-1,3,2,5-dioxaborataphosphoniarinane reacts with diphenylamine and o-aminobenzoic acid with the formation of 5-(aminomethyl)-2,2,5-triphenyl-1,3,2,5-dioxaborataphosphoniarinanes, whereas 1,5,3,7-diammoniadiphosphacyclooctanes are formed with m- and p-aminobenzoic acids. With o-aminobenzoic acid, hydroxymethylphosphines and hydroxymethylphosphonium salts give the corresponding aminomethylphosphines and aminomethylphosphonium salts.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1340–1343, June, 1989.Deceased.     

斯德酮与芳香胺的Mannich反应

3－（4－甲基苯甲酰基乙基）斯德酮和3－（3－羟基－3－苯基丙基）斯德酮 可以与芳香胺发生Mannich反应，得到斯德酮与芳香胺的Mannich碱。     

The important role of the phosphorus lone pair in phosphole aromaticity

Calculations on phosphole systems using the G3MP2B3 model chemistry show that the phosphorus lone pair is critical to the system's aromaticity. Protonation of the lone pair results in antiaromatic molecules as measured by homomolecular homodesmotic reactions. Attempts to separate out effects of hyperconjugation on the butadiene portion of the system are unsuccessful with current practices. Because these hyperconjugation effects will tend to cancel each other in the phosphole systems, analyses using the unmodified homomolecular homodesmotic reactions are considered reasonable measures of their aromaticity. © 2007 Wiley Periodicals, Inc. Heteroatom Chem 18:754–758, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20364     

Oxidative Mannich reaction of N-carbobenzyloxy amines with 1,3-dicarbonyl compounds

Efficient carbon-carbon bond formation at the alpha-position of nitrogen was established by one-pot oxidative Mannich reaction of N-carbobenzyloxy (Cbz) amines with 1,3-dicarbonyl compounds using N-tert-butylbenzenesulfinimidoyl chloride as an oxidant.     

The physical nature of the lone pair

Despite the large number of experimental and theoretical studies on the size, shape, and orientation of lone pairs and their resulting stereochemical character, lone pairs still remain poorly defined in terms of quantitative observable properties of a molecule. Using the conformation of saturated molecules and barriers to internal rotation, experimental chemists have arrived at conflicting sizes and orientations for lone pairs. Most theoretical attempts to define lone pair properties have centered on such non-observables as localized molecular orbitals or have been based on studies on isolated molecules.The use of observable properties to construct a consistent set of physical models to analyze the physical nature of lone pairs is discussed. Much as one probes an electric field with a test charge, probes such as H⁺, H^–, He and H could be used to probe regions of molecules such as NH₃ and H₂O where lone pairs are often postulated to exist.Ab initio quantum mechanical studies can be analyzed using electron density (and resulting changes during interaction), total pair density of electrons, the electrostatic potential about the molecule and bond energy analysis to study lone pair properties. A simple study of NH₃ using an H⁺ probe is presented to clarify the approach.     

Enhancement of Benzylic basicity by a fluorine substituent at the para- position: a case of lone pair/lone pair repulsion

The introduction of a halogen atom at any aromatic position of toluene considerably accelerates the base-promoted deprotonation of the methyl group. p-Fluorotoluene is the only exception; proton abstraction from its benzylic site occurs approximately at one tenth of the rate found with toluene (at -75 degrees C). Lone-pair repulsion appears to be at the origin of the decrease in acidity. Chloro- and bromotoluenes instantaneously exchange benzylic hydrogen against metal when treated with solution of lithium 2,2,6,6-tetramethylpiperidide (LITMP) in diethyl ether in the presence of potassium tert-butoxide and N,N,N',N",N"-pentamethyldiethylenetriamine at -100 degrees C. Due to extensive side reactions ("aryne" formation as a consequence of concomitant deprotonation of aromatic sites adjacent to the halogen atom), products can be isolated only in moderate yield (10-35%), but they are regioisomerically pure.     

New compounds via Mannich reaction of cytosine, paraformaldehyde and cyclic secondary amines

The Mannich reaction of cytosine, paraformaldehyde and cyclic secondary amines in the presence of acetic acid gives 5-(4′-morpholinyl)methylcytosine, 5-(1′-piperidinyl)methylcytosine, 5-(1′-pyrrolidinyl)methylcytosine, 5-(4′-methyl-1′-piperidinyl)methylcytosine, 5-(3′-methyl-1′-piperidinyl)methylcytosine and 5-(2′-methyl-1′-piperidinyl)methylcytosine. These products are quite different from those obtained via cytosine aminomethylation previously described in the literature.     

Reactions of triethylborate with amines

Russian Chemical Bulletin -     

Reactions of chloroalkyl-gem-dichlorocyclopropanes with amines

N-Alkylation of primary and secondary amines with monochloroalkyl-gem-dichlorocyclopropanes under conditions of thermal and microwave heating results in the corresponding amino-gem-dichlorocyclopropanes. With microwave irradiation heating, the reaction time has been decreased to 1 h, the yields of the amines containing gem-dichlorocyclopropane moiety being the same. Formation of the bicyclic amine in reaction of cis-2,3-dichloromethyl-gem-dichlorocyclopropane with primary amines under conditions of phasetransfer catalysis has been studied.     

Reactions of coordinated molecules XI. The reaction of the rhenium tetracarbonyl metallo-acetylacetone complex with hydrazines

The reaction of the rhenium tetracarbonyl metallo-acetylacetone molecule, cis-(OC)₄Re[C(CH₃)OHO(CH₃)C], with hydrazine, methylhydrazine and phenylhydrazine affords the corresponding acetyl-amine complexes, cis-(OC)₄- Re(COCH₃)(NH₂R), where R = H, CH₃, or C₆H₅, and acetonitrile. The reactions were followed by proton NMR at 36°C. The half-lilfe of the reaction with phenylhydrazine was 8.67 minutes while the other two hydrazines gave complete reaction within 30 seconds. The X-ray molecular structure determination of the acetyl-aniline complex is reported.     

Reactions of sulfites with secondary amines

The interaction of diethylamine and morpholine with diphenyl, methyl phenyl, ethyl phenyl, and isopropyl phenyl sulfites was studied. It was established that two reactions, substitution and alkylation, can occur in parallel. Diphenyl sulfites react with amines to give only substitution products, while other sulfites react with substitution at the sulfur atom and with alkylation of the amines. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1395–1397, July, 1998.     

Hydrolysis of cyclic phosphoramides. Evidence for syn lone pair catalysis

Hydrolysis between 1.5 < pH < 4 of five and six membered cyclic phosphoramides has been followed by UV and 3'PNMR spectroscopy. The observed rates fit the equation: k(obs) = k(H2O) [H+]/([H+] + Ka) + k'(H2O), where k(H2O) and k'(H2O) are the pseudo first-order rate constants of water attack on the protonated phosphoramide and its unprotonated form, respectively, and Ka is the phosphoramide acidity equilibrium constant. Although, faster hydrolysis rates on the five membered ring are expected due to the energy released in going from a strained cyclic to a "strained free" trigonal-bipyramidal-pentacoordinated intermediate, with one of the cyclic nitrogens occupying the apical position. these compounds react slightly faster (k(H2O) values) but slower regarding the k'(H2O) values than the six membered analogs. The balance in reactivity is attributed to the additional stability obtained in the six membered cyclic compounds by a syn orientation of the two lone pairs of the cyclic nitrogen to the water attack. This stabilization does not exist in the five membered phospholidines since the water attack is perpendicular to the electron pairs of the cyclic nitrogen. In agreement with the incoming water orientation, the product ratios from the hydrolysis show that in the five membered rings the main product is the one produced by endocyclic cleavage; meanwhile, in the six membered cyclic phospholines the kinetic product is the one produced by exocyclic cleavage. The syn orientation of two electron pairs on nitrogen stabilizes the transition state of water approach to the phosphoramides by ca. 3 kcal mol(-1) when compared to the orthogonal attack.     

Reactions of coordinated trimethylphosphite with binary fluorides

Fluorination of free trimethylphosphite by phosphorus pentafluoride or tungsten hexafluoride involves complex formation followed by rapid F-for-OCH₃ exchange and Michaelis-Arbusov rearrangement reactions (D.W.A. Sharp et al., $\text{J. Chem. Soc. A}$, 1969, 872; J.M. Winfield et al., $\text{ibid}$, 1970, 501). Reactions between WF₆ or PF₅ and P(OCH₃)₃, coordinated to Fe^II (low spin d⁶-inert) or Cu^I (d¹⁰ -labile) cations in CH₃CN, counter anions PF₆^? or AsF₆^?, are very different as evidenced by an n.m.r. study.Reactions between Fe^IIP(OCH₃)₃ and WF₆ are very slow at room temperature; the major products are CH₃PF₄ and WOF₄.NCCH₃. Reactions between Cu^IP(OCH₃)₃ and WF₆ or PF₅ are rapid, even below room temperature, and depend on the stoicheiometry. The major products are W₂O₂F₉^? and a PF₅X^? species, or OPF₃, minor products include CH₃OPF₂, (CH₃O)₂PF, and PF₃. When the mole ratio coordinated P(OCH₃)₃:WF₆ is 1:1, additional W₂O₂F₉ and PF₅X n.m.r. signals are observed.The reactions involve fluorination of free P(OCH₃)₃ whose concentration in solution is limited by the metal cation, and in the reaction between PF₅ and Cu^IP(OCH₃)₃ PF₅.P(OCH₃)₃ has been identified as the initial product. Conventional Michaelis-Arbusov rearrangements are of minor importance as CH₃CN acts as a sink for CH₃⁺, but the final step in the formation of CH₃PF₄ is of this type.     

Stereochemistry of post-transition metal oxides: revision of the classical lone pair model

The chemistry of post transition metals is dominated by the group oxidation state N and a lower N-2 oxidation state, which is associated with occupation of a metal s(2) lone pair, as found in compounds of Tl(I), Pb(II) and Bi(III). The preference of these cations for non-centrosymmetric coordination environments has previously been rationalised in terms of direct hybridisation of metal s and p valence orbitals, thus lowering the internal electronic energy of the N-2 ion. This explanation in terms of an on-site second-order Jahn-Teller effect remains the contemporary textbook explanation. In this tutorial review, we review recent progress in this area, based on quantum chemical calculations and X-ray spectroscopic measurements. This recent work has led to a revised model, which highlights the important role of covalent interaction with oxygen in mediating lone pair formation for metal oxides. The role of the anion p atomic orbital in chemical bonding is key to explaining why chalcogenides display a weaker preference for structural distortions in comparison to oxides and halides. The underlying chemical interactions are responsible for the unique physicochemical properties of oxides containing lone pairs and, in particular, to their application as photocatalysts (BiVO(4)), ferroelectrics (PbTiO(3)), multi-ferroics (BiFeO(3)) and p-type semiconductors (SnO). The exploration of lone pair systems remains a viable a venue for the design of functional multi-component oxide compounds.     

Reactions of primary amines with tetracyanoethylene

Primary amines, 3-triethoxysilylpropylamine, 3-silatranylpropylamine, and cyclohexylamine, react with tetracyanoethylene in acetonitrile at room temperature via addition at the cyano group to afford the corresponding amidines. N-Cyclohexyltricyanoacrylamidine exists as a mixture of two of the three possible isomers, while N-(3-triethoxysilylpropyl)tricyanoacrylamidine and N-(3-silatranylpropyl)tricyanoacrylamidine exist mainly as a single isomer containing NH₂ group. N-(3-Triethoxysilylpropyl)tricyanoacrylamidine was used to prepare gels and films.Translated from Zhurnal Organicheskoi Khimii, Vol. 40, No. 9, 2004, pp. 1308–1314.Original Russian Text Copyright © 2004 by Ladilina, Semenov, Kurskii, Khorshev, Domrachev.