- Reactivity of (Bicyclo[5.1.0]octadienyl)iron(1+) Cations: Application to the Synthesis of cis-2-(2′-Carboxycyclopropyl)glycines
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The addition of carbon and heteroatom nucleophiles to (bicyclo[5.1.0]octadienyl)Fe(CO)2L+ cations 5 or 8 (L = CO, PPh3) generally proceeds via attack at the dienyl terminus on the face of the ligand opposite to iron to generate 6-substituted (bicyclo[5.1.0]octa-2,4-diene)iron complexes (11 or 13). In certain cases, these products are unstable with respect to elimination of a proton and the nucleophilic substituent to afford (cyclooctatetraene)Fe(CO)2L (4 or 7). Decomplexation of 13f, arising from addition of phthalimide to 8, gave N-(bicyclo[5.1.0]octa-3,5-dien-2-yl)phthalimide (19). Oxidative cleavage of 19 (RuCl3/NaIO4) followed by esterification gave the cyclopropane diester 22, which upon hydrolysis gave cis-2-(2′ -carboxycyclopropyl)glycine (CCG-III, 18) (eight steps from 4, 43% overall yield). This methodology was also utilized for preparation of stereospecifically deuterated CCG-III (d-18) and optically enriched (-)-18. Deprotonation of 22 resulted in cyclopropane ring opening to afford the benzoindolizidine (23).
- Wallock, Nathaniel J.,Donaldson, William A.
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p. 2997 - 3007
(2007/10/03)
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- Novel enantioselective synthesis of trans-α-(2-carboxycyclo-prop-1- yl)glycines: Conformationally constrained L-glutamate analogues
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D- and L-α-(2-carboxycycloprop-1-yl)glycines were synthesized from trans-1,3-di(2-furyl)propenone. Conversion of the double bond to a cyclopropane is followed by the formation of an oxime ether. Enantioselective reduction of the oxime ether, separation of diastereomers and oxidation of the furane rings gave enantiomerically pure D- and L-CCG I and CCG II. The structure of oxime 7b was determined by X-ray crystal structure analysis. The key step is the oxazaborolidine catalyzed enantioselective conversion of oxime ethers to amines.
- Demir, Ayhan S.,Tanyeli, Cihangir,Cagir, Ali,Nawaz Tahir,Ulku, Dincer
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p. 1035 - 1042
(2007/10/03)
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- Facile synthesis of (2S,1'S,2'S)-2-(carboxycyclopropyl)glycine an isotype-selective agonist of metabotropic glutamate receptors
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(2S,1'S,2'S)-2-(Carboxycyclopropyl)glycine (L-CCG-I) was synthesized in 12 steps and 14% overall yield by using Sharpless's asymmetric dihydroxylation reaction and stereochemically controlled cyclopropanation as key steps.
- Ma, Dawei,Ma, Zhaochun
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p. 7599 - 7602
(2007/10/03)
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- Study of the reactivity profile of glycine Schiff's bases with dipolarophiles: Application towards a concise synthesis of CCG-II
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The reactivity profile of glycine Schiff's bases with crotonate and bromocrotonate has been shown to take a different course depending on the choice substituent on the imine. Application of the above study for the mild and concise synthesis of CCG-II has been achieved.
- Chavan, Subhash. P.,Venkatraman,Sharma, Anil. K.,Chittiboyina, Amar Gopal
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p. 2857 - 2858
(2007/10/03)
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- Synthesis of Four Diastereomeric L-2-(Carboxycyclopropyl)glycines. Conformationally Constrained L-Glutamate Analogues
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To determine what conformations of L-glutamate (L-Glu) activate that compound's different receptors in the mammalian central nervous system, four diastereochemically L-2-(carboxycyclopropyl)glycines, 1-4, which are conformationally constrained analogues o
- Shimamoto, Keiko,Ishida, Michiko,Shinozaki, Haruhikio,Ohfune, Yasufumi
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p. 4167 - 4176
(2007/10/02)
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- D-3,4-'cyclopropylglutamate' isomers as nmda receptor ligands: Synthesis and enantioselective activity
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Dirhodium(II) tetraacetate catalyzed decomposition of ethyl diazoacetate in the presence of D-Cbz-vinylglycine methyl ester (11) afforded a mixture of the cyclopropyl esters D-CGA A-D (13) from which the corresponding 2R-acids 7-10 were obtained and their absolute configurations assigned. The (2R,3S,4R) α-(carboxycyclopropyl)glycine (D-CGA C, 9 resulted to be the most potent and selective among the NMDA receptor ligands yet reported.
- Pellicciari, Roberto,Natalini, Benedetto,Marinozzi, Maura,Monahan, Joseph B.,Snyder, James P.
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p. 139 - 142
(2007/10/02)
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- threo-Selective Michael Addition of N,N-Dibenzylglycinate and Alaninate Enolates to α,β-Unsaturated Esters. A Concise and Stereoselective Synthesis of (+/-)-CCG-II
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Lithium enolates of N,N-dibenzylglycinate and alaninate added to β-substituted α,β-unsaturated esters, and threo-adducts were obtained in high stereoselectivities.The reaction was employed in a concise and stereoselective synthesis of (+/-)-CCG-II.
- Yamaguchi, Masahiko,Torisu, Kazuhiko,Minami, Toru
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p. 377 - 380
(2007/10/02)
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- Kinetic Resolution of Unnatural and Rarely Occuring Amino Acids: Enantioselective Hydrolysis of N-Acyl Amino Acids Catalyzed by Acylase I
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Acylase I (aminoacylase; N-acylamino-acid amidohydrolase, EC 3.5.1.14, from porcine kidney and the fungus Aspergillus) is broadly applicable enzymatic catalyst for the kinetic resolution of unnatural and rarely occuring α-amino acids.Its enantioselectivity for the hydrolysis of N-acyl L-α-amino acids is nearly absolute, yet it accepts substrates having a wide range of structure and functionality.This paper reports the initial rates of enzyme-catalyzed hydrolysis of over 50 N-acyl amino acids and analogues, the stabilities of the enzymes in aqueous and aqueous/organic solutions, and the effects of different acyl groups and metal ions on the rates of enzymatic hydrolysis.Eleven α-amino and α-methyl α-amino acids were resolved on a 2-29-g scale.Crude L- and D-amino acid products had generally >90percent ee.The utility of resolved amino acids as chiral synthons was illustrated by the preparation of (R)- and (S)-1-butene oxide and the diastereoselective (cis:trans, 7-8:1) iodolactonization of three 2-amino-4-alkenoic acid derivatives.
- Chenault, H. Keith,Dahmer, Juergen,Whitesides, George M.
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p. 6354 - 6364
(2007/10/02)
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- THE PALLADIUM(II)-ASSISTED SYNTHESES OF (+)-Α-(METHYLENECYCLOPROPYL) GLYCENE AND (+)-TRANS-α-(CARBOXYCYCLOPROPYL) GLYCINE, TWO BIOACTIVE AMINO ACIDS.
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Title compounds 1 and 2 have been synthesized efficiently from β-hydroxyallylglycine derivative 3 via the Pd(II)-catalyzed reactions.
- Kurokawa, Natsuko,Ohfune, Yasufumi
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- The Synthesis of a Cyclopropane Amino Acid, trans-α-(Carboxycyclopropyl)glycine, found in Ackee Seed
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trans-α-(Carboxycyclopropyl)glycine, a constituent of ackee seed (Blighia sapida), has been synthesized via the key intermediate ethyl (E)-4,4-diethoxybut-2-enoate.
- Landor, Stephen R.,Landor, Phyllis, D.,Kalli, Michael
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p. 2921 - 2926
(2007/10/02)
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