- Synthesis of novel chiral NiII complexes of dehydroalanine Schiff bases and their reactivity in asymmetric nucleophilic addition reactions. Novel synthesis of (S)-2-carboxypiperazine
-
New chiral NiII complexes of Schiff bases of dehydroalanine with modified chiral auxiliaries (S)-2-N-[N′-(3,4-dichlorobenzyl)prolyl] aminobenzophenone (3,4-DCBPB), (S)-2-N-[N′-(3,4-dimethylbenzyl)prolyl] aminobenzophenone (3,4-DMBPB), (S)-2-N-[N′-(2-chlorobenzyl)prolyl] aminobenzophenone (2-CBPB), and (S)-2-N-[N′-(2-fluorobenzyl)prolyl]- aminobenzophenone (2-FBPB) have been synthesized. Asymmetric Michael addition reactions of primary and secondary amines and thiols to the dehydroalanine moieties of the complexes were studied. (S)-2-FBPB was found to be the best chiral auxiliary in terms of both selectivity of the reactions (de ~92-96%) and reactivity of the complexes. A novel synthetic route toward (S)-2-carboxypiperazine was developed based on the auxiliary.
- Saghiyan, Ashot S.,Stepanyan, Lala A.,Manasyan, Luiza L.,Geolchanyan, Arpine V.,Djamgaryan, Silva M.,Ajvazyan, Hrant R.,Panosyan, Henry A.,Maleev, Viktor I.,Saveleva, Tatiana F.
-
scheme or table
p. 2638 - 2645
(2011/02/16)
-
- Stereochemistry of reactions of the inhibitor/substrates L- And D-β-chloroalanine with β-mercaptoethanol catalysed by L-aspartate aminotransferase and D-amino acid aminotransferase respectively
-
Two members of the α-family of PLP-dependent enzymes, L-aspartate aminotransferase and D-amino acid aminotransferase, have been shown to catalyse β-substitution of L- and D-β-chloroalanine respectively with β-mercaptoethanol, reactions typical of the β-family of PLP-dependent enzymes. The reaction catalysed by L-aspartate aminotransferase has been shown to occur with retention of stereochemistry, a typical outcome for reactions catalysed by β-family enzymes. There are also indications that the reaction catalysed by D-amino acid aminotransferase may involve retention of stereochemistry. Both enzymes have been shown to catalyse exchange at C-3 when the appropriate enantiomer of β-chloroalanine is the substrate. The Royal Society of Chemistry 2005.
- Adams, Benjamin,Lowpetch, Kreingkrai,Thorndycroft, Faye,Whyte, Sheena M.,Young, Douglas W.
-
p. 3357 - 3364
(2007/10/03)
-
- Synthesis of Optically Active 1,4-Thiazane-3-carboxylic Acid via Optical Resolution by Preferential Crystallization of (RS)2-Amino-3-[(2-chloroethyl)sulfanyl]propanoic Acid Hydrochloride
-
Optically active 1,4-thiazane-3-carboxylic acid [TCA] was synthesized from cysteine via optical resolution by preferential crystallization. The intermediate (RS)-2-amino-3-[(2-chloroethyl)sulfanyl]propanoic acid hydrochloride [(RS)-ACS-HCl] was found to exist as a conglomerate based on its melting point, solubility and IR spectrum. (RS)-ACS·HCl was optically resolved by preferential crystallization to yield (R)- and (S)-ACS·HCl. (R)- and (S)-ACS·HCl thus obtained were recrystallized from a mixture of hydrochloric acid and 2-propanol, taking account of the solubility of (RS)-ACS·HCl, efficiently yielding both enantiomers in optically pure forms. (R)- and (S)-TCA were then respectively synthesized by the cyclization of (R)- and (S)-ACS·HCI in ethanol in the presence of triethylamine.
- Shiraiwa, Tadashi,Tadokoro, Kohya,Tanaka, Haruyuki,Nanba, Keiichiro,Yokono, Noriyoshi,Shibazaki, Katsuyoshi,Kubo, Motoki,Kurokawa, Hidemoto
-
p. 2382 - 2387
(2007/10/03)
-