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Lactam Derivatives (lactam + derivative)
Selected AbstractsPreparation and Structure of Di(2-azulenyl)ketene Adducts. ,-Lactone and ,-Lactam Derivatives.CHEMINFORM, Issue 19 2004Shingo Ito Abstract For Abstract see ChemInform Abstract in Full Text. [source] A study of the reaction between 2,4-disubstituted-2,3-dihydro-1,5-benzothiazepines and ketenes generated in situ from chloro and dichloroacetyl chloridesJOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 3 2001Qi-Yi Xing In the presence of triethyl amine, the reaction of 2,4-disubstituted-2,3-dihydro-1,5-benzothiazepine with chloro and dichloroacetyl chlorides produced not only the expected ,-lactam derivative of the benzo-thiazepine, but also the ring opening product. Different results were obtained when the substituent at 2-position of the benxothiazepine varied from methyl to aryl, and the substituent on the chloroacetyl chloride varied from H to Cl, or when carrying out the reaction at different temperatures. The structures of the obtained products and the reaction mechanism are discussed. [source] Structure elucidation and NMR assignments of two new pyrrolidinyl quinoline alkaloids from chestnut honeyMAGNETIC RESONANCE IN CHEMISTRY, Issue 5 2009Giangiacomo Beretta Abstract The complete 1H, 13C and 15N NMR spectral assignments of two new alkaloids isolated from chestnut honey and structurally related to kynurenic acid have been made using 1-D and 2-D NMR techniques, including COSY, HMQC and HMBC experiments. The new compounds have been identified as 3-(2,-pyrrolidinyl)-kynurenic acid and its ,-lactam derivative. Copyright © 2009 John Wiley & Sons, Ltd. [source] Ring Expansion versus Cyclization in 4-Oxoazetidine-2- carbaldehydes Catalyzed by Molecular Iodine: Experimental and Theoretical Study in ConcertADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 10 2010Benito Alcaide Abstract Molecular iodine (10,mol%) efficiently catalyzes the ring expansion of 4-oxoazetidine-2-carbaldehydes in the presence of tert -butyldimethylsilyl cyanide, or allylic and propargylic trimethylsilanes to afford protected 5-functionalized-3,4-dihydroxypyrrolidin-2-ones with good yield and high diastereoselectivity, through a C3C4 bond cleavage of the ,-lactam nucleus. Interestingly, in contrast to the iodine-catalyzed reactions of 3-alkoxy-,-lactam aldehydes which lead to the corresponding ,-lactam derivatives (rearrangement adducts), the reactions of 3-aryloxy-,-lactam aldehydes under similar conditions gave ,-lactam-fused chromanes (cyclization adducts) as the sole products, through exclusive electrophilic aromatic substitution involving the C3 aromatic ring and the carbaldehyde. In order to support the mechanistic proposals, theoretical studies have been performed. [source] On the mechanism and stereochemistry of the formation of ,-lactam derivatives of 2,4-disubstituted-2,3-dihydro-benzo[1,4]diazepinesJOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 5 2001Hong-Zhong Wang 2-Chloro-4-phenyl-2a-(4,-methoxyphenyl)-3,5-dihydroazatetracyclic [1,2- d]benzo [ 1,4]diazepin-1 -one (IIIa) and 2-chloro-4-methyl-2a-(4,-methoxyphenyl)-3,5-dihydroazatetracyclic[1,2- d]-benzo[1,4]diazepin-1-one (IIIb) were synthesized. 1-Benzoyl-2-phenyl-4-(4,-methoxyphenyl)[1,4]-benzodiazepine (IIa) was formed through benzoylation of starting material 2-phenyl-4-(4,-methoxyphenyl)-[1,4]benzodiazepine (Ia) with the inversion of seven-member ring boat conformation. The thus formed ,-lactams should have four pairs of stereoisomers. However, only one pair of enantiomers (2S,2R,4R) and (2R,2aS,4S) was obtained. The mechanism and stereochemistry of the formation of these compounds were studied on the basis of nmr spectroscopy and further confirmed by X-ray diffraction. [source] Molecular and crystalline structures of three (S)-4-alkoxycarbonyl-2-azetidinones containing long alkyl side chains from synchrotron X-ray powder diffraction dataACTA CRYSTALLOGRAPHICA SECTION B, Issue 6 2009Luis E. Seijas The (S)-4-alkoxo-2-azetidinecarboxylic acids are optically active ,-lactam derivatives of aspartic acid, which are used as precursors of carbapenem-type antibiotics and poly-,-aspartates. The crystal structures of three (S)-4-alkoxo-2-azetidinecarboxylic acids with alkyl chains with 10, 12 and 16 C atoms were solved using parallel tempering and refined against the X-ray powder diffraction data using the Rietveld method. The azetidinone rings in the three compounds display a pattern of asymmetrical bond distances and an almost planar conformation; these characteristics are compared with periodic solid-state, gas-phase density-functional theory (DFT) calculations and MOGUL average bond distances and angles from the CSD. The compounds pack along [001] as corrugated sheets separated by approximately 4.40,Å and connected by hydrogen bonds of the type N,H...O. [source] Extensive structure,activity studies of lactam derivatives of MT-II and SHU-9119: their activity and selectivity at human melanocortin receptors 3, 4, and 5CHEMICAL BIOLOGY & DRUG DESIGN, Issue 5 2003P. Grieco Abstract: The melanocortin system is involved in the regulation of several diverse physiologic pathways. Recently we have demonstrated that replacing His6 by Pro6 in the well-known antagonist SHU-9119 resulted in a potent agonist at the hMC5R (EC50 = 0.072 nm) with full antagonist activity at the hMC3R and the hMC4R. We have designed, synthesized, and pharmacologically characterized a series of peptide analogs of MT-II and SHU-9119 at the human melanocortin receptors MC3R, MC4R and MC5R. All these peptides were modified at position 6 with a Pro instead of a His residue. In this study, we have identified new scaffolds which are antagonists at the hMC4R and hMC3R. Additionally, we have discovered a new selective agonist at the hMC4R, Ac-Nle-c[Asp-Pro-D-Phe-Arg-Trp-Lys]-Pro-Val-NH2 (6, PG-931) which will be useful in further biologic investigations of the hMC4R. PG-931 was about 100-fold more selective for the hMC4R vs. the hMC3R (IC50 = 0.58 and 55 nm, respectively). Some of these new analogs have exceptional biologic potencies at the hMC5R and will be useful in further efforts to differentiate the substructural features responsible for selectivity at the hMC3R, hMC4R, and hMC5R. [source] | ||||||||||