- Synthesis of highly functionalized 2,5-disubstituted pyrrolidines via an aza-Morita-Baylis-Hillman-type reaction
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An aza-Morita-Baylis-Hillman-type reaction of Michael acceptors with 5-substituted cyclic N,O-acetals derived from pyrrolidines has been investigated. It has been found that the combination of Me2S and TMSOTf work well with unhindered and reactive enals and enones whilst the use of quinuclidine and TMSOTf is superior for more hindered Michael acceptors. The reactions lead to 2,5-trans-disubstituted pyrrolidines with good to excellent diastereoselectivity. The origin of the selectivity is discussed.
- Kitulagoda, James E.,Palmelund, Anders,Aggarwal, Varinder K.
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supporting information; experimental part
p. 6293 - 6299
(2010/10/19)
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- Scale-up of trisodium [(3Β,5Β,12α)-3-[[4(S)-4-[bis[2- [bis[(carboxy-kO)methyl]aminokN] ethyl]amino-kN]-4-(carboxy-kO)-1-oxobutyl] amino]-12-hydroxycholan-24- oato(6-)]gadolinate(3-)], a Gd(III) complex under development as a contrast agent for MRI coronary angiography
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Process chemistry involved in the discovery and development routes to trisodium [(3Β,5Β,12α)-3-[[4(S)-4-[bis[2-[bis[(carboxykO) methyl]amino-kN]ethyl]amino-kN]-4-(carboxy-kO)-1-oxobutyl]- amino]-12- hydroxycholan-24-oato(6-)]gadolinate(3-)] (B22956/1) starting from L-glutamic acid and (3α,5Β,12α)-3,12-dihydroxycholan-24-oic acid is described. The best process is based on seven chemical steps and overcomes difficult purification protocols. Such process has been successfully implemented to prepare multikilogram batches of the target compound in 20% overall yield from (3α,5Β,12α)-3,12-dihydroxycholan-24-oic acid.
- Anelli, Pier Lucio,Brocchetta, Marino,Lattuada, Luciano,Manfredi, Giuseppe,Morosini, Pierfrancesco,Murru, Marcella,Palano, Daniela,Sipioni, Marco,Visigalli, Massimo
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scheme or table
p. 739 - 746
(2010/04/22)
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- Synthesis, determination of the absolute stereochemistry, and evaluations at the nicotinic acetylcholine receptors of a hydroxyindolizidine alkaloid from the ant Myrmicaria melanogaster
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The first chiral synthesis of new hydroxyindolizidine alkaloid (1) detected in the ant Myrmicaria melanogaster has been achieved, and its absolute stereochemistry was determined to be 3S, 5R, 8S, 9S by the present chiral synthesis.
- Zhou, Dejun,Toyooka, Naoki,Nemoto, Hideo,Yamaguchi, Kaoru,Tsuneki, Hiroshi,Wada, Tsutomu,Sasaoka, Toshiyasu,Sakai, Hideki,Tezuka, Yasuhiro,Kadota, Shigetoshi,Jones, Tappey H.,Garraffo, H. Martin,Spande, Thomas F.,Daly, John W.
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experimental part
p. 565 - 571
(2009/12/05)
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- Blood pool agents for nuclear magnetic resonance diagnostics
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The present invention relates to bile acid conjugates and complexes thereof with gadolinium or manganese ions and the salts thereof with physiologically compatible organic or inorganic bases, a process for the preparation thereof and contrastographic diagnostic pharmaceutical compositions containing them.
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Page/Page column 17; 27; 51
(2008/12/06)
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- First enantioselective synthesis of a hydroxyindolizidine alkaloid from the ant Myrmicaria melanogaster
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The first enantioselective synthesis of the recently reported ant alkaloid 1 has been achieved starting from commercially available lactam 3 in seven steps and 25% overall yield. The proposed structure of the natural product was confirmed by comparison with synthetic 1 and its absolute configuration established as 3S,5R,8S,9S. Georg Thieme Verlag Stuttgart.
- Toyooka, Naoki,Zhou, Dejun,Nemoto, Hideo,Tezuka, Yasuhiro,Kadota, Shigetoshi,Jones, Tappey H.,Garraffo, H. Martin,Spande, Thomas F.,Daly, John W.
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scheme or table
p. 1894 - 1896
(2009/04/08)
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- Synthesis of [6-13C]-L-lysine
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A short and efficient enantioselective synthesis of [6-13C]-L-lysine from commercially available N-benzyloxycarbonyl-L-glutamic acid α-methyl ester is described using [13C]-sodium syanide as the source of isotopic label.
- Sutherland,Willis
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- An efficient route to the α-methyl ester of L-glutamic acid, and its conversion into cis-5-hydroxy-L-pipecolic acid
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The treatment of the N-benzyloxycarbonyl α-methyl esters of L-glutamine or L-asparagine with tert-butyl nitrite in refluxing acetonitrile results in selective hydrolysis of the amide group, giving optically pure Z-Glu-OMe (74%) or Z-Asp-OMe (88%); these are versatile chiral building blocks, and an efficient synthesis of cis-5-hydroxy-L-pipecolic acid from Z-Glu-OMe is described.
- Adams, David R.,Bailey, Patrick D.,Collier, Ian D.,Heffernan, John D.,Stokes, Stephen
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p. 349 - 350
(2007/10/03)
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- A convenient N-protection of pyroglutamate derivatives
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Esters of pyroglutamic acid were N-protected by conventional protective groups (Z. Boc, and COOMe) in high yield, without racemization, using LiHMDS in THF at -78°C and ZCl, Boc2O, and ClCOOMe, respectively.
- Li,Sakamoto,Kato,Kikugawa
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p. 4045 - 4052
(2007/10/03)
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- Oxidation of L-Proline Methyl Ester Derivatives with the Iodosylbenzene/Trimethylsilylazide Reagent Combination
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Oxidation of a series of L-Proline derivatives with the (PhIO)n/TMSN3 reagent combination is reported.Subsequent utilization of the 5-azido N-acyl functionality as a N-acyl iminium ion precursor is described.
- Magnus, Philip,Hulme, Christopher
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p. 8097 - 8100
(2007/10/02)
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- A Novel Synthesis of L-Pyroglutamic Acid Derivatives from L-Proline: Utility of N-Protecting Groups for Ruthenium Tetroxide Oxidation of Cyclic α-Amino Acids
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The utility of four urethane type N-protecting groups, benzyloxycarbonyl (Z), p-nitrobenzyloxycarbonyl , trichloroethoxycarbonyl (Troc) and tert-butoxycarbonyl (Boc) groups, was tested in the ruthenium tetroxide (RuO4) oxidation of N-protected L-proline esters.Three groups, but not the Z group, which was decomposed by RuO4, were found to be stable during the oxidation and afforded high yields of the corresponding L-pyroglutamic acid esters.Removal of the protecting groups from the oxidation products was carried out successfully in the usual manner to give N-unsubstituted (NH-type) L-pyroglutamic acid derivatives without racemization.The first transformation of L-proline into L-pyroglutamic acid and its derivatives has been accomplished.Keywords - oxidation; ruthenium tetroxide oxidation; lactam synthesis; L-pyroglutamic acid synthesis; carboxamide N-protection; ruthenium tetroxide; L-proline; L-pyroglutamic acid; twophase method.
- Yoshifuji,Shigeyuki,Tanaka, Ken-ichi,Kawai, Tomoyuki,Nitta, Yoshihiro
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p. 3873 - 3878
(2007/10/02)
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- THE FIRST CHEMICAL CONVERSION OF L-PROLINE TO L-GLUTAMIC ACID
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The ruthenium tetroxide oxidation of N-acyl-L-proline esters gave the corresponding L-pyroglutamic acid derivatives in good yields with no appreciable racemization, which lead to the first chemical conversion of L-proline to L-glutamic acid.
- Yoshifuji, Shigeyuki,Matsumoto, Hideyo,Tanaka, Ken-ichi,Nitta, Yoshihiro
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p. 2963 - 2964
(2007/10/02)
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