Chiral esters

K. Rettinger, V. Karl, H.-G. Schmarx, E. Dettmar, U. Hener and A. Mosandl, Chirospeciflc analysis of 2-alkyl-branched alcohols, acids and esters chirality evaluation of 2-methylbutanoates from apples and pineapples , Phytochem. Anal. 2 184-188 (1991). 

Hydroperoxides, as optically active oxidizing agents 289-291 Hydrosulphonylation 172 /J-Hydroxyacids 619 a-Hydroxyaldehydes, synthesis of 330 a-Hydroxyalkyl acrylates, chiral 329 j -Hydroxycarboxylic esters, chiral 329 3-Hydroxycycloalkenes, synthesis of 313 Hydroxycyclopentenones, synthesis of 310 -Hydroxyesters 619 synthesis of 616 Hydroxyketones 619, 636 Hydroxymethylation 767 a-Hydroxysulphones, synthesis of 176 / -Hydroxysulphones 638, 639 reactions of 637, 944 electrochemical 1036 synthesis of 636 y-Hydroxysulphones 627 synthesis of 783... 

Substituted conjugated Ester Chiral amino acid... 

Ferreira V, Jarauta I, Ortega L, Cacho J (2004) Simple strategy for the optimization of solid-phase extraction procedures through the use of solid-liquid distribution coefficients—application to the determination of aliphatic lactones in wine. J Chromatogr A 1025 147 Rettinger K, Karl V, Schmarr HG, Dettmar F, Hener U, Mosandl A (1991) Chirospecific analysis of 2-alkylbranched alcohols, -acids, and -esters chirality evaluation of 2-methylbutanoates from apples and pineapples. Phytochem Anal 2 184... 

Miyazawa, T. Kurita, S. Shimaoka, M. Ueji, S. Yamada, T. Resolution of racemic carboxylic acids via the lipase-catalyzed irreversible transesterification of vinyl esters. Chirality 1999, 11 554-560. 

C-Oxo Acid or Ester Chiral Amine Catalyst Yield (%) Amino Acid ee(%) Configuration Ref. 

Synthesis of Optically Active p-Hydroxy Esters. Chiral amino alcohols such as quinine have been used in the enantio-selective synthesis of (3-hydroxy esters via an indium-induced Re-formatsky reaction (eq 14). Although the enantioselectivities are not particularly high, aromatic aldehydes have produced the best results to date. The absolute stereochemistry of the products has not yet been assigned. 

By using asymmetric alcohol residues in the ester, chirality could be induced at the ring carbon atoms. C0CI2 and NiBr2 were used as catalysts, in presence of Nal. The nickel-catalyzed reaction... 

The binuclear copper complex 4 is also an effective catalyst for enantioselective cyclo-propanation of simple olefins76. The major tram-isomer is produced by the -enantiomer of 4 with predominant (15) configuration. For these reactions the influence of the menthyl ester chirality is not negligible otherwise the relatively high difference in the ee values when the R-or S-catalyst is used cannot be rationalized. Thus, double stereodifferentiation seems to operate to some extent. 

O-Alkylation gives the bis-lactim ether shown at the top right of Scheme 3.11. After deprotonation, alkylation occurs stereoselectively such that the electrophile approaches the anion anti to the isopropyl. Typical selectivities for this process are listed in Table 3.2. Advantages of this process are that selectivities are high and that it makes chiral quaternary carbons. Disadvantages are that the electrophiles must often be activated (Le., allylic, benzylic), and that the alkylated amino ester and the amino ester chiral auxiliary must be separated at the end. 

Several recent examples serve to illustrate the potential of allyltributyltin for organic synthesis (Scheme 4). Baldwin and Easton have independently shown that glycine derivatives undergo efficient allylation reactions, providing an avenue for the preparation of non-natural amino acids [8]. Subsequently, addition of glycine-derived radicals to allyltributyltin was shown by Hamon to occur with stereoselectivity if the radical bears an ester chiral auxiliary [9]. An alternative method for the preparation of amino acid derivatives via allylation of carbamoyloxy radicals that are incorporated into an oxazolidin-2-one ring system was reported by Kano... 

Scheme 23.1. Synthesis of metalaxyl-M 1 starting from (S)-lactic acid methyl ester (chiral pool).

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