Esters halides

The conversion of carboxylic acid derivatives (halides, esters and lactones, tertiary amides and lactams, nitriles) into aldehydes can be achieved with bulky aluminum hydrides (e.g. DIBAL = diisobutylaluminum hydride, lithium trialkoxyalanates). Simple addition of three equivalents of an alcohol to LiAlH, in THF solution produces those deactivated and selective reagents, e.g. lithium triisopropoxyalanate, LiAlH(OPr )j (J. Malek, 1972). 

Organic halides, organic acid halides, esters and salts... 

The compound NaBH4 in the presence of Me2N=CHCl" Cl" reduces carboxylic acids to primary alcohols chemoselectively in the presence of halide, ester, and nitrile groups Fujisawa, T. Mori, T. Sato, T. Chem. Lett., 1983, 835. 

This selectivity for preferred reaction displacing the halide is found withboth P(III) and P(V) mixed halide/ester systems (Equation4.15)38 and has been noted in several patents to be of value for phosphonite synthesis (Equation 4.16).39 40... 

As an alternative to the Grignard reagent system noted previously,38 aluminum acetylides react selectively with mixed halide/ester species to replace only the halide (Equation 4.18).49... 

Reaction with acyl halides, esters, or thioesters affords the acylstannanes R SnCOR2, with thioesters giving the cleanest reactions (Equation (44)).84,156... 

Electrochemical fluorination in anhydrous hydrogen fluoride (Simons process) involves electrolysis of organic compounds (ahphatic hydrocarbons, haloalkanes, acid halides, esters, ethers, amines) at nickel electrodes. It leads mostly to perfluori-nated compounds, but is accompanied to a high extent by cleavage and rearrangement reactions. The mechanism of the formation of carbocations according to Eq. (1) and Scheme 1 is assumed... 

R Cu, or lithium or magnesium homocuprates R CuM (M = Li, MgX), are frequently used, but a number of catalytic processes have also been developed. These processes normally utilize a catalytic amount of a copper salt CuY and a stoichiometric amount of an organometallic reagent R M (M = Li, MgX, ZnX, etc.). The leaving groups used include halides, esters, sulfonates, and epoxides, among others. 

Nucleophile substitution of the T1 resin synthesis of phenols, biaryls, alkyl arenes, azides, aromatic hydrazines, halides, ester, azo compounds cinnolines, benzotriazoles [129-137, 140, 141]... 

Three-component reactions between organic electrophile (halide, ester, etc.), carbon monooxide, and organic nucleophile (organometallic compound) (Equation (1)) catalyzed by transition metal complexes afford a powerful method for the synthesis of various ketones. The pioneering works in this area appeared in the early 1980s. 

One synthetic route to the damascones starts with an appropriate cyclogeranic acid derivative (halide, ester, etc.). This is reacted with an allyl magnesium halide to give 2,6,6-trimethylcyclohexenyl diallyl carbinol, which on pyrolysis yields the desired l-(2,6,6-trimethylcyclohexenyl)-3-buten-l-one. Damascone is obtained by rearrangement of the double bond in the side-chain [98]. 

Most of the conformational properties of the acyl derivatives originate in the high polarity of the C=0 bond. Comparative studies have been reported between several chemical functionalities containing the C=0 moiety, i.e., besides heterocyclic aldehydes and ketones, acyl halides, esters, amides, and urethanes, which have different electronic character. Furthermore, the behavior of the C=0 group has been compared, with regard to its conformational properties, to C=C and C=N double bonds in vinyl derivatives, oximes, and azomethines. Most of the results relative to five-membered aromatic heterocycles have been discussed previously (81RCR336 84KGS579). 

Swain, C. G., and C. B. Scott, Quantitative correlation of relative rates. Comparison of hydroxide ion with other nucleophilic reagents toward alkyl halides, esters, epoxides, and acyl halides , J. Am. Chem. Soc., 75, 141-147 (1953). 

Boric oxide is used as a catalyst in many oiganic reactions. It also serves as an intermediate in the production of boron halides, esters, carbide, nitride, and metallic borides. 

Na-Protected a-amino aldehydes 4 are mainly obtained from their corresponding a-amino acid derivatives. Generally the synthetic route proceeds via acid halides, esters, or active amides of a-amino acids that are then reduced. The reduction of N -protected acid halides and esters is often accompanied by some overreduction to the respective alcohols. However, reduction of active amides is apparently free from overreduction. The different procedures described in this review are listed in Table 3. 

Carboxylic Acids and Acid Halides, Esters, and Amides... 

Deep fluorination of alkanes, ethers, acid halides, esters, alkyl chlorides, most ketones, ketals, orthoesters, and combinations of these functional groups produces principally the perfluorinated analogues (Table 2) Chlorine substituents (or chloro groups) usually survive fluorination... 

A variety ol or-amiiio add derivatives, including the acids themselves, halides, esters, and amides can be transformed into hydanloins hy condensation with urea. o-Hydroxy acids and their nitriles give a similar reaction. 

Generally, an alkyl derivative, under appropriate conditions, will eliminate HX, where X is commonly a halide, ester, or -onium function, provided that there is a hydrogen located on the carbon adjacent to that bearing the X function , ... 

In place of a proton source, ie, a Brnmsted acid, a cation source such as an alkyl halide, ester, or ether can be used in conjunction with a Ftiedel-Crafts acid. Initiation with the ether-based initiating systems in most cases involves the halide derivative which arises upon fast halidation by the... 

The reaction accommodates halides, esters, ethers, nitriles, cyclopropanes, epoxides, alcohols and nitio groups. Even carbohydrates can be used.492-494 However, vinylic halides afford aldehydes and ketones... 

The reaction rates decrease in the series C=C RX RNO, and ArN02 RNO and ArNO > C=NOH C=NR > RCN. Arenes, aryl halides, esters, and amides are not reduced. The usual catalyst poisons have no effect or only slight effect. The catalyst is recovered quantitatively and can be reused without purification. 

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