2-Amino-5- 2’-carboxy-6’-hydroxy

Quinolizinium salts, 2-amino-l-hydroxy-diazotization, 2, 542 Quinolizinium salts, l-amino-3-methyl-diazotization, 2, 542 Quinolizinium salts, 2-bromo-synthesis, 2, 544 Quinolizinium salts, carboxy-anhydrides... 

Since the allyl function represents a latent carboxy unit, diastereomerically pure homoallylic alcohols syn-21 or anti-21, obtained by condensation of allylic metals 26 with chiral a-amino aldehydes or acetals (Scheme 6), have been used to prepare the corresponding y-amino-p-hydroxy acids (Scheme 7). 

The use of the aldol condensation to synthesize y-amino-p-hydroxy acids suffers from several drawbacks, such as possible racemization either of the initial carboxy group during its transformation to the a-amino aldehyde, or during any subsequent manipulations of the sensitive CHO moiety. An alternative route involves the direct activation of the carboxy group of the N-protected a-amino acids 30 followed by alkylation with enolates 17 to produce the corresponding p-oxo esters 31.[36 521 The P-oxo esters can be selectively reduced under various conditions to produce diastereomeric mixtures of the target compounds 18 but with retention of the chirality of the initial a-amino acid (Scheme 8). 

Scheme 3 Simple Amino, Carboxy, and Hydroxy Cores and Templates...

Masked chiral a-hetero substituted carboxylic acid enolates have also shown utility in dia-stereoselective additions to nitroalkenes. For example, derivatives of a-hydroxycarboxylic acids, e.g. l,3-dioxolan-4-ones (187) a-amino acids, e.g. 1,3-imidazolidin-4-ones (188) and a-amino-fi-hydroxy-carboxylic acids, e.g. methyl 1,3-oxazolidin-4-carboxylates (189) and methyl l,3-oxazolin-4-carboxy-lates (190), have been employed.1S0a Further, diastereoselective additions of chiral (3-hydroxyesters (191), via the enediolates, to nitroalkenes (40) afford predominant anr/ -P-hydroxyesters (192 Scheme... 

Keywords 2-amino-2 -hydroxy-3,-(methoxycarbonyl)-l,l -binaphthyl, SN2 substitution, 2-metliy lamino-2 -hydroxy-3 -carboxy-1,1 -binaphthyl... 

Copper chelates of amino acid enantiomers such as proline or phenylalanine have been used to resolve enantiomers of amino acids and structurally related compounds [241,245]. Other metals such as zinc and cadmium have also been used. Metal chelates have been used to resolve a-amino-a-hydroxy carboxy acids and a-methyl-a-amino acid enantiomers [246]. One example of pharmaceutical interest is the resolution of D-penicillamine from the L-antipod [247] and resolution of L,D-thyroxine [248]. 

Aldehyde functionalities are very reactive toward amino and hydroxy groups. As a result, polymers 1 can bind to cellnlose or protein snrfaces. Their reactivity toward nucleophiles enables them to take part in varions crosshnking reactions, e.g. with amines. Carboxy fnnctional polysiloxanes 2 are also able to bind to surfaces because of the carboxy group s high polarity. They can nndergo crosslinking reactions, e.g. with epoxides. Their salts are good snrfactants. 

Generally meta-substituted anilines give rise to a mixture of 4- and 6-substituted isatins - - although 4-trifluoromethyl, 4-nitro/ 4-amino, 4-hydroxy, 4-carboxy, 6-methoxy, and 6-bromo isatins have been reported without the other isomer. 

A -Hydrazide Protection A -Amino Protection co-Amino, co-Hydroxy and co-Carboxy Protection Ref... 

Amino-4-hydroxy-6-phenyl- 4yVNaOH 3-Carboxy-2-hydroxy- 375... 

Bromo-3-methoxycarbonylpyrazine with 2,3-dimethylaniline in refluxing toluene gave 2-(2, 3 -dimethylphenyl)amino-3-methoxycarbonylpyrazine (950) [hydrolysis of this product with sodium hydroxide in ethanol gave 2-carboxy-3-(2, 3 -dimethylphenyl)aminopyrazine, which was also obtained by treatment of l-(2, 3 -dimethylphenyl)lumazine with sodium hydroxide in refluxing ethanol (950)]. 3-Bromo-2-hydroxy-5-phenylpyrazine with ammonium hydroxide and copper at 150° gave 3-amino-2-hydroxy-5-phenylpyrazine (365a). Replacement of the iodo substituent from 2-amino-5-iodo-3,6-dimethylpyrazine has been effected with ammonium hydroxide (887). 

The electrolysis products of different carboxylates have been compared with the ionization potentials of the intermediate radicals. From this it appeared that alkyl radicals with gas-phase ionization potentials smaller than 8 eV mainly lead to carbenium ions. Accordingly, a-substituents such as carboxy, cyano or hydrogen support the radical pathway, whilst alkyl, cycloalkyl, chloro, bromo, amino, alkoxy, hydroxy, acyloxy or aryl more or less favor the route to carbenium ions. Besides electronic effects, the oxidation seems also to be influenced by steric factors. Bulky substituents diminish the extent of coupling. The main experimental factors that affect the yield in the Kolbe electrolysis are the current density, the pH of the electrolyte, ionic additives, the solvent and the anode material. 

Amino-5-hydroxy-1,2,3-triazole-4-carboxy-lic acid hydrazide or 1-Amino-4 hydrazido-carbon-5-hydroxytriazoie,(Called 1-Amino-4-hydrazidocarbon-5-oxytria2ol in Ref 2), HO-C-N(NHj) N, mw 158.13, N... 

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