Alkyl and Related Compounds

Based on these generalizations, several studies of alkyl species are of interest. 

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Alkyl and Related Compounds. The i.r. spectra of MeTiClj and Me2TiCl2 and their deuteriated analogues have been redetermined the results do not agree with those obtained in earlier studies, and it would appear that authenticated samples of deuteriated compounds must be obtained before these discrepancies... 

Alkyl and Related Compounds. The alkylzirconium trihalides, RZrXj (R = Me, Et, or Pr X = Cl or Br) have been prepared by treating ZrX4 with R2Zn in toluene at 0°C the dialkylzirconium dihalides, R2ZrX2 (R = Me or Et X = Cl or Br) were obtained from these reactants in pyridine at 0°C. R2Zr.X2,bipy adducts were also obtained. ... 

We will discuss the scarce data that are available on the rates of polymerization in an attempt to critically review their usefulness at the present time. The subject is divided into four types of polymerization that lead to higher aldehyde polymers (a) the so-called crystallization polymerization (b) cationic polymerization (c) anionic polymerization and (d) polymerization with aluminium alkyls and related compounds. 

AHi° values of free radicals can be used to derive mean dissociation energies of metal-carbon bonds in metallic alkyls and related compounds. Thus, if both AH ° (MR , g) and AHf° (R, g) are known, the heat of the disruption process... 

Halostibines, Dihalostibines, and Related Compounds. Alkyl dichi oro- and alkyldibromostibines are readily prepared by the alkylation of the corresponding antimony trihaUde with an organolead reagent (67,104) ... 

Alkyl halides and related compounds azoles without a free NHgroup Alkyl halides and related compounds compounds with a free NH group... 

Alkyl halides and related compounds azoles without a free NHgroup... 

S.06.3.3.4 Alkyl halides, oxonium salts and related compounds... 

Substitution reactions by the ionization mechanism proceed very slowly on a-halo derivatives of ketones, aldehydes, acids, esters, nitriles, and related compounds. As discussed on p. 284, such substituents destabilize a carbocation intermediate. Substitution by the direct displacement mechanism, however, proceed especially readily in these systems. Table S.IS indicates some representative relative rate accelerations. Steric effects be responsible for part of the observed acceleration, since an sfp- caibon, such as in a carbonyl group, will provide less steric resistance to tiie incoming nucleophile than an alkyl group. The major effect is believed to be electronic. The adjacent n-LUMO of the carbonyl group can interact with the electnai density that is built up at the pentacoordinate carbon. This can be described in resonance terminology as a contribution flom an enolate-like stmeture to tiie transition state. In MO terminology,.the low-lying LUMO has a... 

Considerable interest arose during the 1970 s and 1980 s in the use of micro-organisms to produce useful fatty adds and related compounds from hydrocarbons derived from the petroleum industry. During this period, a large number of patents were granted in Europe, USA and Japan protecting processes leading to the production of alkanols, alkyl oxides, ketones, alkanoic adds, alkane dioic acids and surfactants from hydrocarbons. Many of these processes involved the use of bacteria and yeasts associated with hydrocarbon catabolism. 

Hetero-benzylic anionic reagents, derived from 2-alkyl-l,3-oxazoles, -1,3-thiazoles and -imidazoles and related compounds, are not covered in this section because these resemble metallo 1-azaenolates in their reactivity (Section D.l.3.5.). 

Anticancer dtugs can be grouped into several classes, according to their mechanism of action and origin [1]. These are (i) alkylating agents and related compounds which act by forming covalent bonds with cellular... 

Monoalkyltin(IV) compounds can be prepared under suitable conditions from tindl) compounds (44-46). Tin(II) bis(acetylacetonate) (acac) and related compounds react readily with a variety of alkyl bromides or iodides, to give the product RSn(acac)2X, e.g.,... 

It is noteworthy that ZnEt2 has been used as a base in enantioselective allylic substitutions. A remarkable increase in ee was observed when ZnEt2 was used instead of KH, NaH, LiH, LDA, or BuLi in the Pd-catalyzed alkylations of allylic acetates by enolates of malonic esters and related compounds.403 In contrast, application of ZnEt2 was not as very effective as in similar iridium-catalyzed allylic alkylations.404... 

Kharasch, M.S., Jensen, E.V., and Weinhouse, S., Alkylation reactions of tetraethyllead. A new synthesis of ethyldichloroarsine and related compounds,... 

The energetically favorable conformations of model alkyl nitronate (88) and related compounds (89 to 91) (283) were determined by the B3LYP/6-31G(d) method (see Chart 3.9). It appeared that the marked conformations with the minimized dipole moments are energetically most favorable for compounds (88-91) (the use of the dipole-dipole interaction model in conformational analysis was also described in the publication (284)). Calculations including n-n interactions (see Fig. 3.1) did not change this situation because the contribution of this effect is equal in magnitude for both limiting conformations shown in Chart 3.9. 

The C-F bond activations in C6F6 and related compounds with ruthenium [200, 201] and rhodium [17, 78, 201] complexes, for which an SNAr mechanism is energetically unfavorable, have been explained by SET pathways. Both SN2 [128, 129, 131, 170-174, 199, 202] and SET [130, 132, 199] mechanisms have been proposed for the reaction of Co(I) complexes with alkyl and vinyl halides. 

BINOL and related compounds have proved to be effective catalysts for a variety of reactions. Zhang et al.106a and Mori and Nakai106b used an (R)-BINOL-Ti(OPr )4 catalyst system in the enantioselective diethylzinc alkylation of aldehydes, and the corresponding secondary alcohols were obtained with high enantioselectivity. This catalytic system works well even for aliphatic aldehydes. Dialkylzinc addition promoted by TifOPr1 in the presence of (R)- or (A)-BINOL can give excellent results under very mild conditions. Both conversion of the aldehyde and the ee of the product can be over 90% in most cases. The results are summarized in Table 2-14. 

Intramolecular addition of trialkylboranes to imines and related compounds have been reported and the main results are part of review articles [94, 95]. Addition of ethyl radicals generated from Et3B to aldimines affords the desired addition product in fair to good yield but low diaster control (Scheme 40, Eq. 40a) [96]. Similar reactions with aldoxime ethers [97], aldehyde hydrazones [97], and N-sulfonylaldimines [98] are reported. Radical addition to ketimines has been recently reported (Eq. 40b) [99]. Addition of triethylborane to 2H-azirine-3-carboxylate derivatives is reported [100]. Very recently, Somfai has extended this reaction to the addition of different alkyl radicals generated from trialkylboranes to a chiral ester of 2ff-azirine-3-carboxylate under Lewis acid activation with CuCl (Eq. 40c) [101]. 

Interest in the uses of HMPT has also been maintained, but a warning has been issued (by the E. I. du Pont de Nemours Company and the U.S. National Institute for Occupational Safety and Health) about its potential acute toxicity. HMPT has been used in the synthesis of 2,4-bis(dimethylamino)qui nolines,9 8 as a solvent for reactions between carbonyl compounds and sulphur," for the conversion of iV-benzylcarbox-amides into 3-phenylpropionitriles,100 in reactions between metals or organometallic compounds with a variety of organic substrates,101 and as a solvent for alkylation reactions of /J-keto-esters and related compounds in which the alkylation reaction is accompanied by de(alkoxycarbonylation) (Scheme 7).102... 

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