Reaction, work

This reaction worked best with more highly substituted diols and give predominantly syn elimination. 

Note that the Diels-Alder reaction works best when there is an electron-withdrawing group (here CC>2Et) on the olefinic component. 

This reaction works well with monosubstituted epoxides ... 

Another similar example concerns the alkylation of enamines. This reaction works well with reactive a-halocarbonyl compounds (frames 175ff) but simple alkyl hahdes often react on nitrogen ... 

Revision Problem 3 House fJ. Org. Chem., 1965, 3 1061) wanted to study intramolecular Diels-Alder reactions and wanted molecules Uke TM 396 in which n is 3 or 4, so that the product will have a 5 or 6 membered ring if the reaction works. It would obviously be a good thing if the synthesis can easily be modified to make other size rings as well. What do you suggest ... 

This method was designed to produce an acetyl intermediate just like that in the failed recipe a few paragraphs above using only sulfuric acid and acetonitrile [93]. This reaction works, in theory, in a so-so manner on allylbenzene but not on safrole. This method will not make X for many reasons. So why does underground literature and DEA forensic scientists keep claiming that it does Strike doesn t know either. Let s see what the man who invented this. Dr. Ritter, had to say back in 1952 "several attempts to obtain amides from...safrol (sic) were fruitless. [94]. What makes all these people think that this will work unless no one did their homework. This is another sore spot of Strike s and... 

The genome, through its constituent DNAs, provides all of the codes needed for building a wide range of peptides, proteins, and enzymes, which in turn utilize raw materials (food) to form an animate body and keep it going. These multiple reactions work together as a unit within a water-filled cell. 

Dialkylation of an amine or sulfonamide with a 1,3-dihalide provides a further route to azetidines <79CRV33l, 64HC( 19-2)88 5). Examples of this approach are the formation of N-tosylazetidine from tosylamide and l-bromo-3-chloropropane and the formation of N-alkylazetidinyl esters (36). The latter reaction works well except for R=Me the former provides a useful route to azetidine since the tosyl group can be removed by reductive methods. 

In particular we thought it would be useful to include cross-references of functional group transformations and an experimental procedure, so that the reader will be able to evaluate the reaction conditions at a glance for instance is this reaction carried out at room temperature or at 200 C For 1 h or 5 days Are special catalysts required How is the reaction worked up, what yield can be expected ... 

TBDMSOTf, CH2CI2, rt, 24 h, 82% yield. The use of a catalytic amount of the triflate will give the alcohol. If the triflate is used stoichiometrically and the reaction worked up with 2,6-lutidine, the TBDMS ether is isolated (98% yield). "... 

The Mitsunobu reaction is used to convert an alcohol and an acid into an ester by the formation of an activated alcohol (Ph3P, diethyl diazodicar-boxylate), which then undergoes displacement with inversion by the carboxylate. Although this reaction works very well, it suffers from the fact that large quantities of by-products are produced, which generally require removal by chromatography. 

Pd(Ph3P)2Cl2, Bu3SnH, P-NO2C6H4OH, CH2CI2, 70-100% yield. " This reaction works best in the presence of acids. AcOH and pyridinium acetate are also effective. 

Sml2, DMPU, 50-97% yield. " The reaction works well for alkyl-substituted aziridines benzenesulfonamides react faster than tosyl amides. 

These reactions work best with X = I but the less-expensive RBr can be used in conjunction with a Zn-Cu alloy instead of pure Zn. Diaryls are best obtained from appropriate organoboranes or organomercury compounds ... 

Isolated carbonyls always give epoxides from the Corey-Chaykovsky reaction. Take the aldehyde substrate as an example. Spiro epoxide 30 was produced from the reaction of trisnorsqualene aldehyde 28 (R20 represents the polyene side-chain with 20 carbons) with substituted sulfur ylide 29, prepared in situ from cyclopropyldiphenylsulfonium tetrafluoroborate and KOH. " For the epoxidation of ketones, the Corey-Chaykovsky reaction works well for diaryl- (31), arylalkyl- (32), ... 

The Camps reaction has been used to prepare a variety of anti-ulcer agents of the type 23. As can be seen from the yields, the reaction works equally well with electron donating and withdrawing aromatic rings. ... 

The electronic properties of the aniline are important in the Doebner reaction. The reaction works best with electronic donating groups. Anilines substituted with a chlorine at the meta position consistently give low yields, but fluorine at the meta position seems... 

Introduction of an additional methyl group on the donor atom of TMM moiety gives a low 33% yield of the perhydroindans (49, X=H2) and (50, X=H2) with substantial production of the diene by-products [24]. However, it is still remarkable that the reaction works at all since the corresponding intermolecular cycloaddition failed. Incorporation of a carbonyl moiety adjacent to the donor carbon atom doubles the yield of the cycloadducts to 66% (Scheme 2.15). This so-called acyl effect works by making the donor carbon of the TMM unit "softer," thus facilitating the initial step of the conjugate addition, as well as inhibiting base-induced side reactions [22]. 

Dialdehydes 8 have been converted to y-lactones 9 in the presence of a rhodium phosphine complex as catalyst. The example shown below demonstrates that this reaction works also with aldehydes that contain a-hydrogen atoms. 

Although that reaction has been known for more than one hundred years, it is not clear whether the reaction proceeds via pathway (a) or (b) or both. Since the reaction works with a large number of different substrates and under various... 

The reaction works well with primary alkyl halides, especially with allylic and benzylic halides, as well as other alkyl derivatives with good leaving groups. Secondary alkyl halides give poor yields. Tertiary alkyl halides react under the usual reaction conditions by elimination of HX only. Nitriles from tertiary alkyl halides can however be obtained by reaction with trimethylsilyl cyanide 4 ... 

The enolate anion 1 may in principle be generated from any enolizable carbonyl compound 4 by treatment with base the reaction works especially well with /3-dicarbonyl compounds. The enolate 1 adds to the a ,/3-unsaturated compound 2 to give an intermediate new enolate 5, which yields the 1,5-dicarbonyl compound 3 upon hydrolytic workup ... 

The Schiemann reaction seems to be the best method for the selective introduction of a fluorine substituent onto an aromatic ring. The reaction works with many aromatic amines, including condensed aromatic amines. It is however of limited synthetic importance, since the yield usually decreases with additional substituents present at the aromatic ring. 

With respect to aromatic substrates, the Vilsmeier formylation reaction works well with electron-rich derivatives like phenols, aromatic amines and aromatic heterocycles like furans, pyrroles and indoles. However various alkenes are also formylated under Vilsmeier conditions. For example the substituted hexatriene 6 is converted to the terminal hexatrienyl aldehyde 7 in 70% yield ... 

Eee has used chloroaluminate(III) ionic liquids in the Diels-Alder reaction [36]. The endo. exo ratio rose from 5.25 to 19 on changing the composition of the ionic liquid from X(A1C13) = 0.48 to X(A1C13) = 0.51 (Scheme 5.1-16). The reaction works well, giving up to 95 % yield, but the moisture-sensitivity of these systems is a major disadvantage, the products being recovered by quenching the ionic liquid in water. 

The reactions work both ways, and constituents of the alloy being coated may be removed by the halide atmosphere even when interchange does not occur. For example, a nickel-chromium alloy may be superficially dechro-mised by nickel powder in a chloride atmosphere. Thus loss of important alloying constituents may have to be controlled during diffusion coating processes. 

Note that in the S l reaction, which is often carried out under acidic conditions, neutral water can act as a leaving group. This occurs, for example, when an alkyl halide is prepared from a tertiary alcohol by reaction with HBr or HC1 (Section 10.6). The alcohol is first protonated and then spontaneously loses H2O to generate a carbocation, which reacts with halide ion to give the alkyl halide (Figure 11.13). Knowing that an SN1 reaction is involved in the conversion of alcohols to alkyl halides explains why the reaction works well only for tertiary alcohols. Tertiary alcohols react fastest because they give the most stable carbocation intermediates. 

Mixed Claisen-like reactions can also be carried out between an ester and a ketone, resulting in the synthesis of a jS-diketone. The reaction works best when the ester component has no a hydrogens and thus can t act as the nucleophilic donor. For example, ethyl formate gives high yields in mixed Claisen condensations with ketones. 

Intramolecular Claisen condensations can be carried out with diesters, just as intramolecular aldol condensations can be carried out with diketones (Section 23.6). Called the Dieckmann cyclization, the reaction works best on 1.6-diesters and 1,7-diesters. Intramolecular Claisen cyclization of a 1,6-diester gives a five-membered cyclic /3-keto ester, and cyclization of a 1,7-diester gives a six-membered cyclic /3-keto ester. 

Ten years after Sharpless s discovery of the asymmetric epoxidation of allylic alcohols, Jacobsen and Katsuki independently reported asymmetric epoxidations of unfunctionalized olefins by use of chiral Mn-salen catalysts such as 9 (Scheme 9.3) [14, 15]. The reaction works best on (Z)-disubstituted alkenes, although several tri-and tetrasubstituted olefins have been successfully epoxidized [16]. The reaction often requires ligand optimization for each substrate for high enantioselectivity to be achieved. 

If a dilute solution of hydrogen peroxide in dry acetonitrile is added to a solution of a sulphoxide and an iron(II) salt in dry acetonitrile then the sulphone is produced in quantitative yield34. This latter reaction works equally well for aliphatic and aromatic sulphoxides and is thought to involve oxygen transfer by the reaction of a ferryl ion with the sulphoxide, as shown in equation (12). 

Bondietti, E.A. Reynolds, S.A. "Proc. Actinide-Sediment Reactions Working Meeting" Ames. L.L., Ed. BNWL-2117 Batelle Northwest Lab. Richland, 1976. 

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