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Cyclization Strategy (cyclization + strategy)
Selected AbstractsChemInform Abstract: Dianion Cyclization Strategy for the Synthesis of Macrosilaheterocycles (V).CHEMINFORM, Issue 42 2008Maya S. Singh Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Dianion cyclization strategy for the synthesis of macrosilaheterocyclesHETEROATOM CHEMISTRY, Issue 5 2008Maya S. Singh A practical and efficient method for the preparation of silaheterocycles is described. The key step involves the initial formation of symmetrical chiral ditopic ligand, N,N,-1,2-cyclohexylenebis(salicylideneimine) followed by sequential deprotonation with NaH to form dianion intermediate, which reacts with diorganodichlorosilanes to furnish dibenzodioxadiazasilamacrocycles. The products were characterized by satisfactory elemental analyses and spectral (IR, 1H, 13C, 29Si NMR, and Mass) studies. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:455,460, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20460 [source] Solid-phase synthesis of cyclic analogues related to the hypoglycaemic peptide hGH[6,13]: Comparison of two i,i+4 lactam cyclization proceduresJOURNAL OF PEPTIDE SCIENCE, Issue 10 2001Vittoria Cavallaro Abstract The use of 1,3-diisopropylcarbodiimide (DIC) for the synthesis of cyclic analogues of the hypoglycaemic peptide fragment derived from the N -terminus of human growth hormone (hGH), namely hGH[6,13], is described. Different strategies were examined to achieve improved yields for the on resin side-chain to side-chain cyclization of the corresponding linear peptides containing reverse , - turn motifs. When compared with the more reactive Castro's reagent, the results confirm that DIC in the presence of HOBt can be successfully employed to minimize the formation of intermolecular oligomeric by-products associated with the preparation of cyclic hGH[6,14] peptide analogues based on an i,(i+4)Lys,Glu or Glu,Lys cyclization strategy. Copyright © 2001 European Peptide Society and John Wiley & Sons, Ltd. [source] Total Synthesis of Ouabagenin and OuabainCHEMISTRY - AN ASIAN JOURNAL, Issue 5 2009Maddi, Sridhar Reddy Dr. Abstract All done! A full account of the total synthesis of ouabagenin and ouabain has been described. The synthesis was achieved through a polyanionic cyclization strategy. Degradation studies provide an ultimate proof for a key intermediate observed in the synthesis. A full account of the total synthesis of ouabagenin and ouabain is described. A highly stereocontrolled anionic cycloaddition for the rapid construction of the basic steroid skeleton is a pivotal conversion for the whole strategy. A careful study was needed to establish the order and the sequence of functional group manipulations. Specific conformational features of the ouabain skeleton allowed us to overcome a few stereochemical problems. Degradation studies on ouabain provided an ultimate proof for a key intermediate, which is used as a relay. Late stage butenolide formation and glycosidation yielded ouabain. [source] | ||||||||||