Amino acids cyclic deriv

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... 

Title Cyclic Amino Acids and Derivatives Thereof Useful as Pharmaceutical Agents... 

Any kind of C-Mannich base has been actually allowed to react with a variety of amines, including aminoalcohols and amino acids. Cyclic amines, - including optically active derivatives, - and amides arc also employed as are a number of aromatic heterocycles. 

Direct and indirect enzymatic methods for the preparation of enantiopure cyclic fi-amino acids and derivatives from /1-lactams 04MI36. 

A special type of enzymatic peptide synthesis employs activated heterocyclic amino acid/peptide derivatives as acyl donors (Scheme 3.28) [327]. In a kinetically controlled approach, 5(4//)-oxazolones (which may be regarded as cyclic activated esters ) are cleaved by a-chymotrypsin thereby generating an acyl enzyme intermediate. Then the amino acid/peptide segment is coupled onto the W-terminus of the acyl acceptor by forming a new peptide bond. 

Cytidine 2, 3 -cyclicphosphate, polymeric complexes of Cd" and Cu" and cytidine 5 -phosphate, l-(j8-D-arabinofuranosyl)cytosine Pt complex. Adenosine complexed with 5-bromouracil, iS-methyl-5 -thioadenosine, 2, 3 -0-isopropyIideneadenosine, 2, 3 -0-(2-carboxyethyl)ethylideneadeno-sine, the amino-acid adenosine derivatives (5) and (6) which are constitutents of tRNA, 8-[(2-aminoethyl)amino]adenosine 3, 5 -cyclic phosphate. 8-Iodoguanosine, 2-JV-methylguanosine, a guanosine Hg" complex, 2, 35 -tri-(9-acetyl-6-0-(mesitylenesulphonyl)-guanosine, guanosine 5 -phosphate, Cu" complex. ... 

Enzymatic cascade providing access to cyclic amino acid (AA) derivatives by the combination of AAO with /V-methyi amino acid dehydrogenase (NMAADH) starting either from a linear or cyclic AA. 

Pentafluorobenzyl bromide has been used in the derivatization of mercaptans [55] and phenols [36], m the analysis of prostaglandins [37], and in quantitative GC-MS [5S] 1,3 Dichlorotetrafluoroacetone is used for the derivatization of amino acids to the corresponding cyclic oxazolidinones and allows the rapid analysis of all 20 protein ammo acids [d] Pentafluorophenyldialkylchlorosilane derivatives have facilitated the gas chromatographic analysis of a wide range of functionally substituted organic compounds, including steroids, alcohols, phenols, amines, carboxylic acids, and chlorohydrms [4]... 

Optically active five- or six-membered cyclic A -acyliminium ions of this type are generated from the a-inethoxy derivatives, easily obtainable through anodic methoxylation of intermediates that are prepared via ex-chiral-pool syntheses from certain natural amino acids. Reaction of 5-substituted five-membered cyclic A -acyliminium ions with various nucleophiles leads to the predominant formation of cw-products with moderate selectivity. The trans-selective reaction with alkyl copper reagents appears to be an exception. 

The AB polyamides are made from either >-amino acids or cyclic lactams, derivatives of the oj-amino acids (Table 3.1). In these polymers, the amino and acid groups are inherently balanced and the polymer also contains one amino and one acid endgroup. There are a number of different routes available for polymerizing these AB-type polyamides ... 

Hydantoinases belong to the E.C.3.5.2 group of cyclic amidases, which catalyze the hydrolysis of hydantoins [4,54]. As synthetic hydantoins are readily accessible by a variety of chemical syntheses, including Strecker reactions, enantioselective hydantoinase-catalyzed hydrolysis offers an attractive and general route to chiral amino acid derivatives. Moreover, hydantoins are easily racemized chemically or enzymatically by appropriate racemases, so that dynamic kinetic resolution with potential 100% conversion and complete enantioselectivity is theoretically possible. Indeed, a number of such cases using WT hydantoinases have been reported [54]. However, if asymmetric induction is poor or ifinversion ofenantioselectivity is desired, directed evolution can come to the rescue. Such a case has been reported, specifically in the production of i-methionine in a whole-cell system ( . coli) (Figure 2.13) [55]. 

Heteroatom rings, such as that found in quinoline derivatives, can be generated from amino-ketones with [hydroxy(tosyloxy)iodo]benzene and perchloric acid. Cyclic imines are converted to pyridine derivatives with NCS and then excess sodium methoxide. ... 

Some other types of macrocycle compounds have been synthesized using adamantane and its derivatives. Recently, a new class of cyclobisamides has been synthesized using adamantane derivatives, which shows the general profiles of amino acid (serine or cystine)-ether composites. They were shown to be efficient ion transporters (especially for Na+ ions) in the model membranes [159]. Another interesting family of compounds to which adamantane derivatives have been introduced in order to obtain cyclic frameworks is crown ethers [160]. The outstanding feature of these adamantane-bearing crown ethers (which are also called diamond crowns ) is that ot-amino acids can be incorporated into the adamantano-crown backbone [160]. This family of... 

The process is not limited to acyclic amino acids, as cyclic compounds such as proline and pipecolic acid derivatives can also be employed, though in these cases more complex heterobicyclic substances are formed. 

Asymmetric 1,3-dipolar cycloaddition of cyclic nitrones to crotonic acid derivatives bearing chiral auxiliaries in the presence of zinc iodide gives bicyclic isoxazolidines with high stereoselectivity (Eq. 8.51). The products are good precursors of (3-amino acids such as (+)sedridine.73 Many papers concerning 1,3-dipolar cycloaddition of nitrones to chiral alkenes have been reported, and they are well documented (see Ref. 63). 

In NRPs and hybrid NRP-PK natural products, the heterocycles oxazole and thiazole are derived from serine and cysteine amino acids respectively. For their creation, a cyclization (or Cy) domain is responsible for nucleophilic attack of the side-chain heteroatom within a dipeptide upon the amide carbonyl joining the amino acids [61]. Once the cyclic moiety is formed, the ring may be further oxidized, to form the oxazoline/thiazoline, or reduced, to form oxazolidine/thiazolidine (Figure 13.20). For substituted oxazoles and thiazoles, such as those... 

The analytical data obtained, particularly by the PUMA mass spectrometer on board Vega 1 during the flyby, indicate the presence of a large number of linear and cyclic carbon compounds, such as olefins, alkynes, imines, nitriles, aldehydes and carboxylic acids, but also heterocyclic compounds (pyridines, pyrroles, purines and pyrimidines) and some benzene derivatives no amino acids, alcohols or saturated hydrocarbons are, however, present (Kissel and Krueger, 1987 Krueger and Kissel, 1987). 

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