115859-55-7Relevant articles and documents
Stereoselective synthesis of β-hydroxy-α-amino acids β-substituted with non-aromatic heterocycles
Cremonesi, Giuseppe,Dalla Croce, Piero,Fontana, Francesco,Forni, Alessandra,La Rosa, Concetta
, p. 1667 - 1675 (2007)
We have stereoselectively synthesised β-hydroxy-α-amino acids β-substituted with non-aromatic heterocycles by means of a condensation reaction between enantiomerically pure heterocyclic aldehydes and the (R)-(+)-2,5-dihydro-3,6-dimethoxy-2-isopropylpyrazi
Highly selective asymmetric Rh-catalyzed hydroformylation of heterocyclic olefins
Chikkali, Samir H.,Bellini, Rosalba,De Bruin, Bas,Van Der Vlugt, Jarl Ivar,Reek, Joost N. H.
experimental part, p. 6607 - 6616 (2012/06/15)
A small family of new chiral hybrid, diphosphorus ligands, consisting of phosphine-phosphoramidites L1 and L2 and phosphine-phosphonites L3a-c, was synthesized for the application in Rh-catalyzed asymmetric hydroformylation of heterocyclic olefins. High-pressure (HP)-NMR and HP-IR spectroscopy under 5-10 bar of syngas has been employed to characterize the corresponding catalyst resting state with each ligand. Indole-based ligands L1 and L2 led to selective ea coordination, while the xanthene derived system L3c gave predominant ee coordination. Application of the small bite-angle ligands L1 and L2 in the highly selective asymmetric hydroformylation (AHF) of the challenging substrate 2,3-dihydrofuran (1) yielded the 2-carbaldehyde (3) as the major regioisomer in up to 68% yield (with ligand L2) along with good ees of up to 62%. This is the first example in which the asymmetric hydroformylation of 1 is both regio- and enantioselective for isomer 3. Interestingly, use of ligand L3c in the same reaction completely changed the regioselectivity to 3-carbaldehyde (4) with a remarkably high enantioselectivity of 91%. Ligand L3c also performs very well in the Rh-catalyzed asymmetric hydroformylation of other heterocyclic olefins. Highly enantioselective conversion of the notoriously difficult substrate 2,5-dihydrofuran (2) is achieved using the same catalyst, with up to 91% ee, concomitant with complete regioselectivity to the 3-carbaldehyde product (4) under mild reaction conditions. Interestingly, the Rh-catalyst derived from L3c is thus able to produce both enantiomers of 3-carbaldehyde 4, simply by changing the substrate from 1 to 2. Furthermore, 85% ee was obtained in the hydroformylation of N-acetyl-3-pyrroline (5) with exceptionally high regioselectivities for 3-carbaldehyde 8Ac (>99%). Similarly, an ee of 86% for derivative 8Boc was accomplished using the same catalyst system in the AHF of N-(tert-butoxycarbonyl)-3-pyrroline (6). These results represent the highest ees reported to date in the AHF of dihydrofurans (1, 2) and 3-pyrrolines (5, 6).
MELANOCORTIN RECEPTOR AGONISTS
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Page/Page column 47-48, (2010/02/11)
The present invention relates a compound of formula 1, and pharmaceutically acceptable salt, hydrate, solvate, or isomer thereof effective as agonist of melanocortin receptor, and an agonistic composition of melanocortin receptor comprising the same as active ingredient.
