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Search for "lactams" in Full Text gives 136 result(s) in Beilstein Journal of Organic Chemistry.

Tandem catalysis of ring-closing metathesis/atom transfer radical reactions with homobimetallic ruthenium–arene complexes

  • Yannick Borguet,
  • Xavier Sauvage,
  • Guillermo Zaragoza,
  • Albert Demonceau and
  • Lionel Delaude

Beilstein J. Org. Chem. 2010, 6, 1167–1173, doi:10.3762/bjoc.6.133

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  • generate active species in situ. The two catalytic processes were first carried out independently in a case study before the whole sequence was optimized and applied to the synthesis of several polyhalogenated bicyclic γ-lactams and lactones from α,ω-diene substrates bearing trihaloacetamide or
  • reactions with homobimetallic ruthenium–indenylidene complex 1 to generate active species in situ. The two catalytic processes were first carried out independently in a case study before the whole sequence was optimized and applied to the synthesis of several polyhalogenated bicyclic γ-lactams and lactones
  • a diastereomeric mixture of unsaturated bicyclic lactams 11 (Table 3, entry 2). The two products were separated by column chromatography. 2D NMR spectroscopy and mass spectrometry analyses confirmed that dehydrochlorination had occurred during the catalytic process. Further work is underway to
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Published 08 Dec 2010

Novel tetracyclic structures from the synthesis of thiolactone-isatin hybrids

  • Renate Hazel Hans,
  • Hong Su and
  • Kelly Chibale

Beilstein J. Org. Chem. 2010, 6, No. 78, doi:10.3762/bjoc.6.78

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  • containing a bridged amide bond. Essentially, the amide functionality adopts a planar conformation in normal amides with stability being conferred by the delocalization of the nitrogen lone pair into the C=O bond [25]. The amides in bicyclic bridgehead lactams are distorted from planarity and this severely
  • affects their reactivity and stability [26][27][28][29][30][31]. Furthermore, the use of bridged amides as scaffolds in medicinal chemistry has been explored [32][33][34][35][36][37]. Indeed, the enhanced electrophilicity or acylating ability of β-lactams is partially attributed to the distortion from
  • indicated by X-ray crystallographic data. The absence of the other diastereomer may be due to destabilizing steric interactions with the carbonyl group of the amide and the oxygen of the vinyl ether. Similar cyclizations leading to bridged lactams have been reported [43][44]. Synthesis of tetracycles 4 was
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Published 19 Jul 2010

Synthesis of fluorinated δ-lactams via cycloisomerization of gem-difluoropropargyl amides

  • Satoru Arimitsu and
  • Gerald B. Hammond

Beilstein J. Org. Chem. 2010, 6, No. 48, doi:10.3762/bjoc.6.48

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  • difluorodihydropyridinones via a ring-closing metathesis reaction, and of 4,4-difluoro-3-oxoisoquinolines through a ring-closing metathesis–enyne metathesis tandem reaction. These products, in turn, undergo a Diels–Alder reaction to yield heterotricyclic systems in moderate to good yields. Keywords: bicyclic lactams
  • ; cycloisomerization; difluoropropargyl; enyne; ring-closing metathesis; Introduction It has been estimated that as many as 25% of all synthetic pharmaceutical drugs contain an amide bond [1]. Commonly, β- and γ-lactams are present in many natural products and pharmaceuticals, and the introduction of a gem
  • -difluoromethylene moiety has been reported to improve their biological activities. For example, a gem-difluoro-γ-lactam can inhibit γ-lactamase, which is responsible for bacterial resistance to γ-lactam antibiotics [2][3][4]. Additionally, α,α-difluoro lactams are precursors of some biologically active compounds [5
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Published 14 May 2010

Synthesis of lipophilic 1-deoxygalactonojirimycin derivatives as D-galactosidase inhibitors

  • Georg Schitter,
  • Elisabeth Scheucher,
  • Andreas J. Steiner,
  • Arnold E. Stütz,
  • Martin Thonhofer,
  • Chris A. Tarling,
  • Stephen G. Withers,
  • Jacqueline Wicki,
  • Katrin Fantur,
  • Eduard Paschke,
  • Don J. Mahuran,
  • Brigitte A. Rigat,
  • Michael Tropak and
  • Tanja M. Wrodnigg

Beilstein J. Org. Chem. 2010, 6, No. 21, doi:10.3762/bjoc.6.21

Graphical Abstract
  • -deoxynojirimycin [11] such as 5 and 6 (Figure 2) as well as N-substituted D-glucono-δ-lactams 7 (Figure 2) [12] have been shown to be highly potent pharmacological chaperones for the potential treatment of Gaucher [13] and Pompe [14] diseases by ‘rescuing’ the related mutant enzymes. Both Wong [15] and Overkleeft
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Published 01 Mar 2010

Palladium- catalyzed cross coupling reactions of 4-bromo- 6H-1,2-oxazines

  • Reinhold Zimmer,
  • Elmar Schmidt,
  • Michal Andrä,
  • Marcel-Antoine Duhs,
  • Igor Linder and
  • Hans-Ulrich Reissig

Beilstein J. Org. Chem. 2009, 5, No. 44, doi:10.3762/bjoc.5.44

Graphical Abstract
  • derivatives constitute a versatile class of N,O heterocycles [1][2][3][4][5][6][7][8][9][10][11][12][13]. Considerable attention has been paid to 6H-1,2-oxazines 1 bearing a C-4,C-5-double bond [14][15][16][17][18], which are useful intermediates in the synthesis of γ-lactams [19], γ-amino acids [20], amino
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Preliminary Communication
Published 16 Sep 2009

Asymmetric reactions in continuous flow

  • Xiao Yin Mak,
  • Paola Laurino and
  • Peter H. Seeberger

Beilstein J. Org. Chem. 2009, 5, No. 19, doi:10.3762/bjoc.5.19

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  • was developed for the reaction of imino esters with ketenes, leading to the stereoselective synthesis of ß-lactams [30]. Ketene was generated from the corresponding acid chloride with polymer-supported BEMP 17, and was reacted with an imino ester in a reaction catalyzed by the resin-supported quinine
  • flow. Asymmetric synthesis of ß-lactams. α-Chlorination of acid chlorides in flow. Asymmetric Michael reaction in continuous flow. Enantioselective addition of Et2Zn to benzaldehyde using monolithic chiral amino alcohol. Continuous-flow hydrolytic dynamic kinetic resolution of epibromohydrin (32
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Review
Published 29 Apr 2009

A convenient allylsilane- N-acyliminium route toward indolizidine and quinolizidine alkaloids

  • Roland Remuson

Beilstein J. Org. Chem. 2007, 3, No. 32, doi:10.1186/1860-5397-3-32

Graphical Abstract
  • chloride and CeCl3. The mixture was then hydrolysed with 1N HCl to give methylenindolizidinones 5a and 5b in a 4:1 ratio. Reduction of the mixture of lactams 5a and 5b with lithium aluminium hydride gave methylenindolizidines 6a and 6b which were separated by flash chromatography. Osmium tetroxide
  • conditions, 27b led to compound 29b. Another way (cf. Scheme 7) was studied to access (-)-dendroprimine 22: hydrogenation of the crude mixture of cyclisation products 26a and 26b over palladium on carbon provided a mixture of lactams 29a, 30a and 31a in which isomer 30a was preponderant (29a/30a/31a = 15:65
  • in quantitative yield. Reduction of this mixture of lactams with lithium aluminium hydride gave a 7:3 mixture of methylenquinolizidines 38a and 38b in quantitative yield. Osmium tetroxide-catalysed periodate oxidation of the olefinic bond of quinolizidines 38a and 38b under carefully controlled
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Review
Published 02 Oct 2007

Flexible synthesis of poison- frog alkaloids of the 5,8-disubstituted indolizidine- class. II: Synthesis of (-)-209B, (-)-231C, (-)-233D, (-)-235B", (-)-221I, and an epimer of 193E and pharmacological effects at neuronal nicotinic acetylcholine receptors

  • Soushi Kobayashi,
  • Naoki Toyooka,
  • Dejun Zhou,
  • Hiroshi Tsuneki,
  • Tsutomu Wada,
  • Toshiyasu Sasaoka,
  • Hideki Sakai,
  • Hideo Nemoto,
  • H. Martin Garraffo,
  • Thomas F. Spande and
  • John W. Daly

Beilstein J. Org. Chem. 2007, 3, No. 30, doi:10.1186/1860-5397-3-30

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  • antagonist for this receptor, dihydro-β-erythroidine. Results The enantioselective syntheses of (-)-209B, (-)-231C, (-)-233D, (-)-235B", (-)-221I, and what proved to be an epimer of natural 193E, starting from common chiral lactams have been achieved. When we performed electrophysiological recordings to
  • epimer of 193E starting from common chiral lactams, and the absolute stereochemistry of natural (-)-233D was determined. Furthermore, the relative stereochemistry of (-)-231C and (-)-221I was also determined. The present asymmetric synthesis of the proposed structure for 193E revealed that the C-8
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Published 28 Sep 2007

Flexible synthetic routes to poison- frog alkaloids of the 5,8-disubstituted indolizidine- class I: synthesis of common lactam chiral building blocks and application to the synthesis of (-)-203A, (-)-205A, and (-)-219F

  • Naoki Toyooka,
  • Dejun Zhou,
  • Hideo Nemoto,
  • H. Martin Garraffo,
  • Thomas F. Spande and
  • John W. Daly

Beilstein J. Org. Chem. 2007, 3, No. 29, doi:10.1186/1860-5397-3-29

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  • then treatment of the resulting deblocked amino alcohols with trimethylaluminum under Weinreb's conditions [21] gave rise to the lactams 1 and 2 in 71% and 68% overall yields, respectively. To demonstrate the utility of the chiral lactam building blocks, we conducted the total synthesis of
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Published 28 Sep 2007

Reactions of glycidyl derivatives with ambident nucleophiles; part 2: amino acid derivatives

  • Gerald Dyker,
  • Andreas Thöne and
  • Gerald Henkel

Beilstein J. Org. Chem. 2007, 3, No. 28, doi:10.1186/1860-5397-3-28

Graphical Abstract
  • lactams 8 or 6-membered lactones 9 (Table 1). Most interestingly, the lactones 9 were always found as a single diastereoisomer, while for the lactams 8 various ratios of the diastereoisomers were detected (ratio ranging from 7:3 to 4:6, measured by 1H NMR). Under the strongly basic reaction conditions of
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Published 27 Sep 2007

An efficient synthesis of tetramic acid derivatives with extended conjugation from L-Ascorbic Acid

  • Biswajit K. Singh,
  • Surendra S. Bisht and
  • Rama P. Tripathi

Beilstein J. Org. Chem. 2006, 2, No. 24, doi:10.1186/1860-5397-2-24

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  • aldehydes. Wittig olefination followed by reaction of the resulting tetranolactonyl dienyl esters with different amines resulted in the respective 5-hydroxy lactams. Subsequent dehydration of the hydroxy lactams with p-toluene sulphonic acid afforded the dienyl tetramic acid derivatives. All reactions were
  • reaction. Similarly, reaction of dienyl ester 9 with n-propyl-, cyclopropyl-, n-butyl-, iso-butyl-, n-hexyl-, n-octyl- and benzyl amines separately led to the formation of the respective N-alkyl lactams (12–18) in good to very good yields. However, reaction of compound 9, bearing a 3, 4-dibenzyloxy
  • substituent, with selected amines, viz. n-butyl-, n-hexyl and benzyl amines separately under the identical experimental conditions, led to the formation of the respective 5-hydroxy lactam derivatives (19–22) in good yields (see Table 1). Finally, the hydroxy lactams so obtained were dehydrated to the
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Published 06 Dec 2006
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