N,O-Heterocycles as synthetic intermediates (original) (raw)
Related papers
Tetrahedron Letters, 2005
Nitrosation of bis arylidene acetone oximes with nitrous acid in glacial acetic acid gives 3-vinyl pyrazolone-N,N 0 -dioxides in 32-37% yield. Similar reactions of 2-arylidene-6-(hydroxylamino-aryl-methyl)-cyclohexanone oximes give tricyclic compounds with dioxa-2,6-diaza-spiro[4,4]nona-2,8-diene ring systems in 77-84% yield.
Tetrahedron-asymmetry, 2008
The first total synthesis of enantiopure methyl (1S,2S,3R,4S,5R)-2-amino-3,4,5-trihydroxycyclopentanecarboxylate was carried out according to our recent novel strategy for the transformation of nitrohexofuranoses into cyclopentylamines, which is based on an intramolecular cyclization leading to 2-oxabicyclo[2.2.1]heptane derivatives. Differences in reactivity for this key step were rationalized by using molecular mechanism-based calculations.3,5-Di-O-benzyl-6-deoxy-6-nitro-d-glucono-1,4-lactoneC20H21NO7[α]D25=+17.9 (c 2.8, CHCl3)Source of asymmetry: d-glucoseAbsolute configuration: (2R,3R,4R,5R)Methyl 3,5-di-O-benzyl-6-deoxy-6-nitro-α-d-glucofuranosideC21H25NO7[α]D22=-6.0 (c 1.0, CHCl3)Source of asymmetry: d-glucoseAbsolute configuration: (1S,2R,3R,4R,5R)Methyl 3,5-di-O-benzyl-6-deoxy-6-nitro-β-d-glucofuranosideC21H25NO7[α]D22=-77.0 (c 1.0, CHCl3)Source of asymmetry: d-glucoseAbsolute configuration: (1R,2R,3R,4R,5R)(1S,4S,5S,6R,7R)-6,7-Dibenzyloxy-5-nitro-2-oxabicyclo[2.2.1]heptan-3-oneC20H19NO6[α]D21=-35.0 (c 0.8, CHCl3)Source of asymmetry: d-glucoseAbsolute configuration: (1S,4S,5S,6R,7R)(1S,3S,4S,5R,6R,7R)-6,7-Dibenzyloxy-3-methoxy-5-nitro-2-oxabicyclo[2.2.1]heptaneC21H23NO6[α]D22=-23.7 (c 1.2, CHCl3)Source of asymmetry: d-glucoseAbsolute configuration: (1S,3S,4S,5R,6R,7R)(1S,3R,4S,5R,6R,7R)-6,7-Dibenzyloxy-3-methoxy-5-nitro-2-oxabicyclo[2.2.1]heptaneC21H23NO6[α]D19=-47.2 (c 1.0, CHCl3)Source of asymmetry: d-glucoseAbsolute configuration: (1S,3R,4S,5R,6R,7R)Methyl (1S,2R,3S,4R,5S)-2,4-dibenzyloxy-3-hydroxy-5-nitrocyclopentanecarboxylateC21H23NO7[α]D21=+67.0 (c 1.4, CHCl3)Source of asymmetry: d-glucoseAbsolute configuration: (1S,2R,3S,4R,5S)Methyl (1S,2S,3R,4S,5R)-2-benzyloxycarbonylamino-3,4,5-trihydroxycyclopentanecarboxylateC15H19NO7[α]D26=+125.5 (c 2.0, CHCl3)Source of asymmetry: d-glucoseAbsolute configuration: (1S,2S,3R,4S,5R)
2005
Publications and lectures related to the thesis 1. Introduction and aims 2. Results and Discussion 2.1. Synthesis of oxomethanobenzocyclooctenecarboxylic acids and their cyclocondensation to polyheterocycles Synthesis of methanobenzocyclooctene oxo acids Cyclocondensations of methanobenzocyclooctene oxo acids to polyheterocycles 2.2. Isomerization and application of aroylnorbornenecarboxylic acids for the stereoselective preparation of heterocycles 2.3. Preparation and structure of dz'exo-norbornane-fused 1,3-heterocycles and oxanorbornane analogues Preparation and structure of ¿/z'exo-condensed norbornane heterocycles Preparation of difunctional 7-oxabicyclo[2.2.1]heptane/ene derivatives and their use for the synthesis of heterocycles 2.4. Synthesis and stereochemistry of saturated or partially saturated pyridazino[6,1-b]-and phthalazino[ 1,2-6]quinazolinones 22 2.5. Retrodiene reactions. Preparation of heterocycles by retro Diels-Alder reaction Preparation of 1-aminocyclopenta[2,3]pyrrolo[ 1,2-a]pyrimidine-2,6-dione by cycloreversion Preparation of pyrimido[2,l-a]phthalazines and an aminopyrimido[2,1-ajisoindole by retro Diels-Alder reaction 29 Double retro Diels-Alder reaction applied for the preparation of a pyrimido[ 1,2-6]pyridazine 3 3 2.6. Application of fiiran as escaping diene for the preparation of heterocycles Preparation of condensed 1,3-oxazines by retro Diels-Alder reaction 3 5 3. Summary 39 References 41 Acknowledgements Appendix Publications and lectures related to the thesis Full papers
Synthesis of nitrogen containing heterocycles via radical cyclisation
2000
O-benzoyl hydroxamic acids were found to be suitable precursors for the generation of amidyl radicals. A stereoselectivity study was performed to investigate the 5-exo cyclisations of the amidyl radicals formed. Hence a range of methyl and phenyl 2- substituted N-alkyl-Af-benzoyloxy-pent-4-enamides were synthesised and cyclised using tributyltin hydride and AIBN. A small preference for the Irons isomer was observed in all cases (10-36%) with the phenyl pendant series giving the highest selectivities. The observed Irons isomer was not that expected by current theories (Beckwith and Houk model). The effect of the N-substituent was found to exert little or no influence on the stereoselectivity of any of the reactions. Due to the difficulties in removing toxic tin residues from the reaction mixture alternative methods for the generation and 5-exo cyclisation of amidyl radicals utilising A-acyl hydroxamic acids were investigated using Cu(OTf)2 and Sml2. The effect of concentration, solve...
Synthesis of Heterocycles via Radical-Polar Crossover Cycloadditions
2014
! 2 and clinical studies and the final production for widespread treatment. Fortunately, these studies ushered in a variety of chemically similar and even more powerful carbapenem antibiotics. " 4 " The final example in particular underscores the importance of synthetic organic chemistry, as distinguished from other means of producing molecules for medicinal discovery or treatment. In this regard, catalytic and enantioselective reactions have become particularly important. These reactions are often responsible for enabling the mass production of key chiral molecules. The efforts of synthetic organic chemists developing novel methodologies have grown out of a myriad of inspirations, including natural product synthesis, the construction of unique molecular topologies, serendipity, and simple curiosity. Many concerted efforts, however, can be characterized by specific design goals or logical strategies towards developing these new tools. For example, one such focus has been on utilizing small organic molecules, termed organocatalysts, in place of or at an advantage to metals. From this relatively simple prompt, the area of organocatalysis has developed quite broadly. This thesis will demonstrate 5
Journal of the Iranian Chemical Society, 2011
A series of new azines were prepared by reaction of 2-ketoalkyl quinoline derivatives with some hydrazone in solvent free reaction conditions using ultrasonic irradiation. The application of ultrasonic irradiation improved the yields and reduced the reaction times. These azines, due to having α-acidic hydrogen next to azine group and heterocycle ring, have tautomeric forms the degree of each of which was determined on the basis of 13 C NMR, 1 H NMR, UV and IR spectrum. The results revealed that all compounds exist mostly in the enaminone form. We attempted to obtain criss-cross or probably Diels-Alder cycloaddition products through the reaction of some of these new azines with 2-chloroacrylonitrile as a dienophile. Some new diene systems developed from the said reactions.