Bonds dialkylamide

The nonsymmetrie dimethylhydrazine adds exelusively to the triple bond of the ynaminoketones (70-75°C, THF, CH2CI2, 3 h) to form A,A-dialkylamides of 3-oxobutanohydrazonie aeid, whieh exist in solution as a tautomerie mixture of the hydrazonie (371) and enhydrazinie (372) forms, yields 49-54% (87ZOR1635). 

Ketone p-toluenesulphonyl hydrazones can be converted to alkenes on treatment with strong bases such as alkyl lithium or lithium dialkylamides. This reaction is known as the Shapiro reaction68. When w./i-LinsaUi rated ketones are the substrates, the products are dienes. This reaction is generally applied to the generation of dienes in cyclic systems where stereochemistry of the double bond is fixed. A few examples where dienes have been generated by the Shapiro reaction have been gathered in Table 669. 

In reactivity studies of monomeric Be(NPT2)2- it has been shown that CO2 and CS2 insert into the Be—N bonds to give [Be(O2CNPr 2)2] or Be(S2C. Pr 2)21 whereas the dimeric beryllium dialkylamides can afford more complicated structures.The cubanoid complex [ Be(Cl)(p3-NPEt3) 4] was obtained by the thermal Me3SiCl elimination from [BeCl2(Me3SiNPEt3)] ... 

In contrast to the extensive coordination chemistry of Ni—C (alkyl) complexes, examples of nickel complexes containing Ni—N (dialkylamide) a bonds are lacking.1123... 

Separate signals for N-alkyl groups syn or (Z) and anti or ( ) to the carbonyl oxygen are observed for N-N-dialkylamides (Table 4.35) [313-315] due to the amide resonance. But the rotational barrier of the CN partial double bond decreases with increasing size of the carboxylic acid residue R [315]. 

The insertion of carbon dioxide into a transition metal-oxygen bond, e.g., a metal alkoxide, results in an organic carbonate ester, coordinated in either a monodentate or bidentate manner. Only a limited number of such reactions have been observed, and little mechanistic information is available. The reactions may proceed by interaction of C02 with ROH or RO in solution followed by metal coordination, in a manner similar to the C02 reactions with the early transition metal dialkylamides. Alternatively, direct attack of C02 on the alkoxide oxygen might occur, or a C02 adduct may form as an intermediate. 

In addition to C—C bonds, [RhCl(CO)(PPh3)2] (71) has been shown to catalyze the hydroformylation of formaldehyde to give glycol aldehyde (equation 62).336 Small amounts of methanol were obtained as a by-product. The reaction requires N,JV-dialkylamides as solvents, otherwise methanol is the major product and no glycol aldehyde is formed. Coordinated amide solvent was thought... 

The main idea of these techniques lies in the interaction of the active hydrogen atom of the alcohols with the anions of metal hydrides, alkyls, acetylides, nitrides, amides, dialkylamides, bis(trialkylsilyl)amides, sulfides, etc., with formation of compounds where an H atom is bonded by a strong covalent bond (usually gaseous HX). Alkaline hydrides of the most active metals (K, Rb, Cs) are used to slow down the reaction of metal with alcohol sometimes it is necessary simply to avoid explosion. 

Supposedly, lanthanide chemistry is lagging behind main group and d-transition metal chemistry. The concluding statement which Bradley made with respect to transition metal dialkylamides and silylamides almost 20 years ago [19b] is a current topic in lanthanide amide chemistry To date homogenous transition-metal catalysis has been restricted to hydrocarbon systems involving the facile formation and rupture of M-H, M-C, C-H and C-C bonds. An extension to include M-N, C-N, M-O, and C-O bonds seems plausible and could lead to substantial advances in transition-metal catalysis. ... 

Aziridine —> P-lactam.1 This transformation can be effected by insertion of CO into the N-C bond of an aziridine. Thus reaction of N-benzyl-2-methylaziridine (1) with lithium iodide in refluxing THF provides a lithium dialkylamide (a) that reacts with Ni(CO)4 to form the p-lactam 2 in 51% yield. Both reactions probably... 

Poly(vinylidene chloride) also dissolves readily in certain solvent mixtures (82). One component must be a sulfoxide or NJSI-dialkylamide. Effective cosolvents are less polar and have cyclic structures. They include aliphatic and aromatic hydrocarbons, ethers, sulfides, and ketones. Acidic or hydrogen-bonding solvents have an opposite effect, rendering the polar aprotic component less effective. Both hydrocarbons and strong hydrogen-bonding solvents are nonsolvents for PVDC. 

Similarly, the enamine salt 15 is obtained by lithiation of 14 (equation 5). In both cases the lower steric hindrance leads to higher stability of the enaminic system33 where the double bond is formed on the less substituted carbon. The Af-metalated enamines 11 and 15 are enolate analogs and their contribution to the respective tautomer mixture of the lithium salts of azomethine derivatives will be discussed below. Normant and coworkers34 also reported complete regioselectivity in alkylations of ketimines that are derived from methyl ketones. The base for this lithiation is an active dialkylamide—the product of reaction of metallic lithium with dialkylamine in benzene/HMPA. Under these conditions ( hyperbasic media ), the imine compound of methyl ketones 14 loses a proton from the methyl group and the lithium salt 15 reacts with various electrophiles or is oxidized with iodine to yield, after hydrolysis, 16 and 17, respectively (equation 5). 

The coordination number 3 occurs in dialkylamides [e.g., Cr(NPr )3]. A combination of steric factors and multiple Cr—N bonding has been proposed to explain the stability of such monomers. Another of the rare nonoctahedral Cr111 complexes is that shown in (17-C-VII), where there is a distorted pentagonal bipyramid. 

The M-NR2 bond is labile and Nb and Ta dialkylamides M(NR2)5 (12) are valuable starting materials (Scheme 2). They can easily undergo substitution or Insertion reactions. Insertion of CO2, CS2, and COS in M(NR2)5 has been observed, giving dialkylcarbamates, dithiocarbamates, or monothiocarbamate derivatives, respectively. In the case of niobium, the insertion of CS2 is accompanied by reduction. Insertion of CO2 is catalyzed by amines resulting from adventitious hydrolysis. Monodentate as well as bidentate carbamato... 

Many cyclopropenes unsubstituted at C(3)are unstable and nucleophilic addition to the n bond often occurs. Cyclopropene esters 44 are not capable of isolation even when lithium dialkylamides are employed to effect the dehydrohalogenation reaction. Recent... 

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