Chiral from amino acids

Licjuid Crystals. Ferroelectric Hquid crystals have been appHed to LCD (Uquid crystal display) because of their quick response (239). Ferroelectric Hquid crystals have chiral components in their molecules, some of which are derived from amino acids (240). Concentrated solutions (10—30%) of a-helix poly(amino acid)s show a lyotropic cholesteric Hquid crystalline phase, and poly(glutamic acid ester) films display a thermotropic phase (241). Their practical appHcations have not been deterrnined. 

The majority of the original chiral selectors for brush-type CSPs were derived from natural chiral compounds. Selectors prepared from amino acids, such as phenyl... 

The complex obtained from commercially available chiral a-amino acids (AA) with Cu + ion induces asymmetry in the Diels-Alder reaction of 31 (R = H) with 32. By using 10% Cu(II)-AA (AA = L-abrine) the cycloaddition occurs e/iJo-stereoselectively in 48 h at 0°C with high yield and with acceptable enantioselectivity ee = 1A%). This is the first example of enantioselective Lewis-acid catalysis of an organic reaction in water [9b]. 

The test reaction was also investigated by Anderson et al. employing chiral imine-sulfide ligands derived from amino acids.The ligand of choice, depicted in Scheme 1.37, (S)-A-2 -chlorobenzylidene-2-amino-3-methyl-l-thiophenylbutane readily prepared from (5)-valinol, led to an enantioselectivity... 

Armstrong, D.W., Kullman, J.P., Chen, X., Rowe, M. (2001). Composition and chirality of amino acids in aerosol/dust from laboratory and residential enclosures. Chirality 13, 153-158. 

Kibayashi and coworkers have used enantiometrically pure allylic silyl ethers obtained from amino acids in cycloaddition with nitrones (Eq. 8.49).71 Cyclic nitrone reacts with a chiral allyl ether to give selectively the exo and erythro isomer (de 90%). Optically active alkaloids containing a piperidine ring such as (+)-monomorine,71c (+)-coniine,71a and (-)-oncinotine71b have been prepared from the addition product. 

Deacylation of p-nitrophenyl derivatives of amino acids Chiral surfactants derived from amino acids. Comparisons of rates and enantioselectivities Ono etal., 1981... 

Chiral a-amino acids from imines derived from (S)-menthone... 

Oxazolidinone is a versatile functional group and chiral oxazolidinones, readily prepared from amino acids, are premiere auxiliaries with broad utility in synthetic chemistry ". ... 

CSP, beads chiral monomers (from amino acids) analytical to preparative fair, moderate to low... 

The asymmetric transamination from chiral a-amino acids 1021 and amino acid derivatives (57) (esters 86,103), amino alcohols 104 ) to carbonyl functions in prochiral substrates (58) (a-keto acids 102), a-keto esters 86,103), ketones 103b d) was described... 

In 1968, Horeau et al.1441 reported an enantioselective methylation of cyclohexanone via an optically active terpenylimine to yield 2-methylcyclohexanone with 72% enantiomeric excess. The following deals only with those chiral amino compounds that are derived directly from amino acids 14S). 

A series of chiral amines derived from amino acids has been used the best optical yields have been obtained with phenylalanine derivatives (128) (R1 = CH2C6H5) and tert-leucine tert-butyl ester (129) 146>. 

The chiral lactone alcohol derivative (178)181) can be readily prepared from natural (S)-glutamic acid, the cheapest chiral a-amino acid. Lactone (178) was alkylated to yield optically active 3-substituted lactone alcohol derivatives, (179) and (180), which were intermediates in the stereoselective synthesis of various natural products 182). 

Asymmetric transformations of ot-amino acids promoted by optically active metal complexes have been reported by several groups 269). The control of the stereoselective hydrolysis reactions of racemic esters by chiral micellar compounds prepared from amino acids has been intensively investigated 270). 

Traditionally, amino acids have been utilized in the mainstream of organic chemistry primarily as building blocks for peptide syntheses. One may expect that in the future the use of amino acids as starting materials for non-peptide compounds will be a subject of ever-increasing interest. Many chiral target molecules with widely variable structures will be prepared from amino acids in the future. 

The chirality of amino acids stems from the chiral, or asymmetric, center, the a-carbon atom. The a-carbon atom is a chiral center if it is connected to four different substituents. Thus glycine has no chiral center. Two of the amino acids, isoleucine and threonine, possess additional chiral centers because each has one additional asymmetric carbon. You should be able to locate these carbons by simple inspection. 

Figure 8F.3. Chiral phosphine ligands derived from amino acids.

Gallop et al. [80] reported the preparation of p-lactams via a [2+2] cycloaddition reaction of ketenes with resin-bound imines derived from amino acids (Scheme 9). This is another solid-phase adaptation of the Staudinger reaction, which could lead to the synthesis of structurally diverse 3,4-bis-substituted 2-azetidinones [81]. In addition, a novel approach to the synthesis of A-unsubstituted-p-lactams, important building blocks for the preparation of p-lactam antibiotics, and useful precursors of chiral p-amino acids was described [82]. 

From this information, we have estimated(25) that between 0.5 and 1% of the chiral organic salts formed from amino acids and alpha-hydroxy acids have lower threshold powers than KDP for doubling or tripling 1.05 pm light. The probability P of finding such a crystal in a random sample of N crystals from the population of chiral organic salts is given by... 

Toda, F., and Tanaka, K. (1997) New Chiral Ammonium Salt Hosts Derived from Amino Acids Very Efficient Optical Resolution of 2,2 -Dihydroxy-l,r-binaphthyl by Complexation with These Host Compounds, Chem. Commun., 1087-1088. 

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