Halo acids, derivatives

Halo-ketones have conjugated ketones as a synthetic precursor, and halo-acid derivatives have conjugated acid derivatives as a precursor. In both cases, the reaction relies on a reaction with HX (X = Cl, Br). Ketone-dihalides and acid derivative-dihalides also have conjugated ketone or conjugated acid derivatives as precursors, relying on a reaction with Xg (X = Cl, Br). 

An alternative strategy prepared isoxazolidinyl esters by displacement of the halide moiety in a halo-acid derivative by an amine, an amine surrogate. When... 

Halo-acid derivatives are useful precursors to GABOB. Chlorination of 4-amino-butanoic acid (GABA - see section 6.1) gave 3-chloro-4-aminobutanoic acid (6.32)... 

Various alkylating agents are used for the preparation of pyridazinyl alkyl sulfides. Methyl and ethyl iodides, dimethyl and diethyl sulfate, a-halo acids and esters, /3-halo acids and their derivatives, a-halo ketones, benzyl halides and substituted benzyl halides and other alkyl and heteroarylmethyl halides are most commonly used for this purpose. Another method is the addition of pyridazinethiones and pyridazinethiols to unsaturated compounds, such as 2,3(4//)-dihydropyran or 2,3(4//)-dihydrothiopyran, and to compounds with activated double bonds, such as acrylonitrile, acrylates and quinones. 

Reaction of halo sulfonic acid esters with boranes 10-125 Alcoholysis of sulfonic acid derivatives 13-15 Vicarious substitution of aryl nitro compounds... 

Organoboranes can also be used to construct carbon-carbon bonds by several other types of reactions that involve migration of a boron substituent to carbon. One such reaction involves a-halo carbonyl compounds.20 For example, ethyl bromoac-etate reacts with trialkylboranes in the presence of base to give alkylated acetic acid derivatives in excellent yield. The reaction is most efficiently carried out with a 9-BBN derivative. These reactions can also be effected with (3-alkenyl derivatives of 9-BBN to give (3,y-unsaturated esters.21... 

AMINO ACID DERIVATIVES, [NP(NHCH3)2]n MIXED SUBSTITUENT ARYLAMINO AND ALKOXY DERIVATIVES POLYMERIZATION OF ORCANO-HALO TRIMERS POLYMER-BOUND DYES... 

There are very few precedents for the reaction of cyclic a-halo ethers with carbanions. Zelinski and coworkers114 and Schudel and Rice115 reported the preparation of diethyl DL-tetrahydropyran-2-ylmalonate (137) by treatment of 2-bromo- or 2-chloro-tetrahydropyran (136) with diethyl sodiomalonate. The product was subsequently converted into the malonic and acetic acid derivatives, 138 and 139, respectively. The same sequence has also been reported by other workers.116... 

This simple, selective and efficient method was applied to a wide range of aliphatic/ aromatic carboxylic acid derivatives that contain hydroxyl-, halo-, ester and other base-sensitive groups as substituents. 

The acid chlorides have served as useful synthetic intermediates leading to ketones via the malonic acid synthesis and Friedel rafts reaction, thiadiazole acetic acid derivatives, and halo ketones via the Arndt Eistert synthesis and carbinols by hydride reduction <68AHC(9)107>. The dialkylcadmium conversion of acid chlorides into ketones fails in the 1,2,5-thiadiazole series. The major product is either a tertiary carbinol or the corresponding dehydration product, by virtue of the high reactivity of the intermediate ketone. 

The cyclodehydration method used for the synthesis of benzo[a jquinolizinium ion and its congeners (Scheme 97) requires that phenylpyridines (176) (including benzo analogs) be converted into quaternary salts (177) by the action of a -halo ketones or a -halo aldehyde derivatives. The acid-catalyzed cyclization of these salts (177) has provided access to a number of compounds containing the benzo[a]quinolizinium system (178) (Table 8). 

Formation of Acyl Halides from Acid Derivatives Halo-de-acyloxy-substitution Halo-de-halogenation... 

Reaction of halo ketones or diazo ketones with boranes 0-102 Carbonylation of alkyl halides 0-104 Reaction between acyl halides and organometallic compounds 0-105 Reaction between other acid derivatives and organometallic compounds... 

The application of antibiotics as chiral selectors has resulted in the successful resolution of almost all types of neutral, acidic, and basic racemic molecule. These antibiotics have been used for the enantiomeric resolution of amino acids, their derivatives, peptides, alcohols, and other pharmaceuticals. The selectivities of the most commonly used antibiotic-based (vancomycin, teicoplanin, and ristocetin A) CSPs varied from one racemate to another and are given in Table 1. Vancomycin was used for the chiral resolution of amino acids, amines, amides, imides, cyclic amines, amino alcohols, hydantoins, barbiturates, oxazolidinones, acids, profens, and other pharmaceuticals. Teicoplanin was found to be excellent chiral selector for the enantiomeric resolution of amino acids, amino alcohols, imides, peptides, hydantoins, a-hydroxy and halo acids, and oxazolidinones, whereas ristocetin A is capable of chiral resolution of amino acids, imides, amino... 

Grigg et al. [61] have recently reported a one-pot reaction involving the initial three-component condensation with a 2-halo-benzylamine 112, ethyl glyoxylate 113 and an aryl boronic acid 114, followed by Pd cyclization in the presence of carbon monoxide to give 116, or in the presence of allene to form dihydroisoquinoline amino acid derivatives 117 (Scheme 7.15). 

---