Chloride trimethylsilyl

The benzoic acid derivative 457 is formed by the carbonylation of iodoben-zene in aqueous DMF (1 1) without using a phosphine ligand at room temperature and 1 atm[311]. As optimum conditions for the technical synthesis of the anthranilic acid derivative 458, it has been found that A-acetyl protection, which has a chelating effect, is important[312]. Phase-transfer catalysis is combined with the Pd-catalyzed carbonylation of halides[3l3]. Carbonylation of 1,1-dibromoalkenes in the presence of a phase-transfer catalyst gives the gem-inal dicarboxylic acid 459. Use of a polar solvent is important[314]. Interestingly, addition of trimethylsilyl chloride (2 equiv.) increased yield of the lactone 460 remarkabiy[3l5]. Formate esters as a CO source and NaOR are used for the carbonylation of aryl iodides under a nitrogen atmosphere without using CO[316]. Chlorobenzene coordinated by Cr(CO)j is carbonylated with ethyl formate[3l7]. 

In 2-aminothiazole the two N-bonded hydrogens are substituted by the trimethylsilyl group with the reagent trimethylsilyl chloride-triethylamine (Scheme 105) (348). 

Birch reduction of indole with lithium metal in THF in the presence of trimethylsilyl chloride followed by oxidation with p-benzoquinone gave l,4-bis(trimethylsilyl)indoIe (106). This is readily converted in two steps into l-acetyl-4-trimethylsilylindole. Friedel-Crafts acylation of the latter compound in the presence of aluminum chloride yields the corresponding 4-acylindole (107) (82CC636). 

Chemical Designations - Synonyms Chlorotrimethylsilane Trimethylsilyl chloride Chemical Formula (CHjjjSiCl. 

Now, examine the orbital on cyclohexanone lithium enolate most able to donate electrons. This is the highest-occupied molecular orbital (HOMO). Identify where the best HOMO-electrophile overlap can occur. Is this also the most electron-rich site An electrophile will choose the best HOMO overlap site if it is not strongly affected by electrostatic effects, and if it contains a good electron-acceptor orbital (this is the lowest-unoccupied molecular orbital or LUMO). Examine the LUMO of methyl iodide and trimethylsilyl chloride. Is backside overlap likely to be successful for each The LUMO energies of methyl iodide and trimethylsilyl chloride are 0.11 and 0.21 au, respectively. Assuming that the lower the LUMO energy the more effective the interaction, which reaction, methylation or silylation, appears to be guided by favorable orbital interactions Explain. 

The Boekelheide reaction has found utility in other synthetic methodology. An approach to 2,3-pyridynes made use of this chemistry in the preparation of the key intermediate 30. Treatment of 28 with acetic anhydride produced the desired pyridone 29. Lithiation was followed by trapping with trimethylsilyl chloride and exposure to triflic anhydride gave the pyridyne precursor 30. Fluoride initiated the cascade of reactions that resulted in the formation of 2,3-pyridyne 31 that could be trapped with appropriate dienes in Diels-Alder reactions. 

A modified procedure, which uses trimethylsilyl chloride as an additional reagent, gives higher yields of acyloins and is named after Riihlmann. In the presence of trimethylsilyl chloride, the Zjiis-O-silylated endiol 7 is formed and can be isolated. Treatment of 7 with aqueous acid leads to the corresponding acyloin 2 ... 

D(—)-a-amlnophenylacetamido] penicillanic acid Trimethylsilyl chloride Sodium 2-ethyl hexanoate... 

Merck s thienamycin synthesis commences with mono (V-silylation of dibenzyl aspartate (13, Scheme 2), the bis(benzyl) ester of aspartic acid (12). Thus, treatment of a cooled (0°C) solution of 13 in ether with trimethylsilyl chloride and triethylamine, followed by filtration to remove the triethylamine hydrochloride by-product, provides 11. When 11 is exposed to the action of one equivalent of tm-butylmagnesium chloride, the active hydrogen attached to nitrogen is removed, and the resultant anion spontaneously condenses with the electrophilic ester carbonyl four atoms away. After hydrolysis of the reaction mixture with 2 n HC1 saturated with ammonium chloride, enantiomerically pure azetidinone ester 10 is formed in 65-70% yield from 13. Although it is conceivable that... 

THF THP TIPS TIPSOTf TMEDA TMS TMSC1 TMSCN TMS I TMSOTf Ts tetrahydrofuran tetrahydropyranyl tri-isopropylsilyl tri-isopropylsilyl trifluoromethanesulphonate AVV,N N -tetramethylethylenediamine trimethylsilyl trimethylsilyl chloride (chlorotrimethylsilane) trimethylsilyl cyanide (cyanotrimethylsilane) trimethylsilyl iodide (iodotrimethylsilane) trimethylsilyl trifluoromethanesulphonate tosyl (p-tolucnesulphonyl)... 

Trimethylcydohexenone, 59 Trimcthylenemethane, 132 Trimethylsilyl carboxylates. 102. 103. 122 Trimethylsilyl chloride, see TMSCI... 

Due to the high a-C,H acidity in the alkoxyethylidene complexes 6 (e.g.,piCa=8 (R=Me)) [ 16], transformations via an enolate analog are possible and have been used to introduce additional functionality into the carbene side chain to access various Fischer carbene complexes [3]. The a,/J-unsaturated complex 8 could be obtained from 6 (R=Et) by an aldol-type condensation with benzaldehyde 7 in the presence of triethylamine and trimethylsilyl chloride (Scheme 2) [17]. This reaction proceeds completely diastereoselectively to yield only the trans-isomer. Analogously, binuclear complexes have been prepared from 6 and 1,3-and 1,4-phthaldialdehyde in good yields [17]. This type of condensation has... 

Chromium aminocarbenes [39] are readily available from the reaction of K2Cr(CO)5 with iminium chlorides [40] or amides and trimethylsilyl chloride [41]. Those from formamides (H on carbene carbon) readily underwent photoreaction with a variety of imines to produce /J-lactams, while those having R-groups (e.g.,Me) on the carbene carbon produced little or no /J-lactam products [13]. The dibenzylaminocarbene complex underwent reaction with high diastereoselectivity (Table 4). As previously observed, cyclic, optically active imines produced /J-lactams with high enantioselectivity, while acyclic, optically active imines induced little asymmetry. An intramolecular version produced an unusual anti-Bredt lactam rather than the expected /J-lactam (Eq. 8) [44]. 

Such enantioselective deprotonations depend upon kinetic selection between prochiral or enantiomeric hydrogens and the chiral base, resulting from differences in diastere-omeric TSs.27 For example, transition structure E has been proposed for deprotonation of 4-substituted cyclohexanones by base D.28 This structure includes a chloride generated from trimethylsilyl chloride. 

The /V-acy10xaz01 idi n0nes give anti products when addition is effected by a catalytic amount of MgCl2 in the presence of a tertiary amine and trimethylsilyl chloride. Under these conditions the adduct is formed as the trimethylsilyl ether.129... 

When this type of reaction is quenched with trimethylsilyl chloride, rather than by neutralization, a trimethylsilyl ether of the adduct is isolated. This result shows that the tetrahedral adduct is stable until the reaction mixture is hydrolyzed. 

Another convenient procedure for hydrochlorination involves adding trimethylsilyl chloride to a mixture of an alkene and water. Good yields of HC1 addition products (Markovnikov orientation) are formed.3 4 These conditions presumably involve generation of HC1 by hydrolysis of the silyl chloride, but it is uncertain if the silicon plays any further role in the reaction. 

A study aimed at optimizing yields in this reaction found that carbinol formation was a major competing process if the reaction was not carried out in such a way that all of the lithium compound was consumed prior to hydrolysis.113 Any excess lithium reagent that is present reacts extremely rapidly with the ketone as it is formed by hydrolysis. Another way to avoid the problem of carbinol formation is to quench the reaction mixture with trimethylsilyl chloride.114 This procedure generates the disilyl acetal, which is stable until hydrolysis. 

This must reflect activation of the carbonyl group by magnesium ion, since ketones are less reactive to pure dialkylzinc reagents and tend to react by reduction rather than addition.141 The addition of alkylzinc reagents is also promoted by trimethylsilyl chloride, which leads to isolation of silyl ethers of the alcohol products.142... 

Additions to aldehydes are also catalyzed by Lewis acids, especially Ti(i-OPr)4 and trimethylsilyl chloride.154 Reactions of (3-, y-, 8-, and e-iodozinc esters with benzaldehyde are catalyzed by Ti(/-OPr)3Cl.155... 

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