Stereochemical Studies on a New Ciramadol Analogue by NMR-Spectroscopy (original) (raw)
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Aminocyclanols, II: Stereochemical Studies on a New Ciramadol Analogue by NMR‐Spectroscopy
Archiv der Pharmazie, 1994
The absol. configuration of a Ciramadol analogue obtained from (‐)‐menthone is established by 1H‐NMR‐, simulated NMR‐, COSY‐90‐, and NOE‐measurements. The final compound 2‐(α‐1‐pyrrolidino)benzyl‐4‐isopropyl‐1‐methyl‐cyclohexan‐3‐one (4b), e.g., has 1R,2S,4S,11S‐configuration due to stereoselective Michael‐type addition of pyrrolidine to the pertinent benzylidene intermediate 3.
Helvetica Chimica Acta, 1998
5S)-1-Benzoyl-3-[(E)-cyanomethylidene]-5-(methoxycarbonyl)pyrrolidin-2-one (5) was prepared in four steps from l-pyroglutamic acid (1). 1,3-Dipolar cycloadditions of diazomethane (6) and 2,4,6-trimethoxybenzonitrile oxide (7) gave substituted 1,2,7-triazaspiro[4.4]non-1-en-6-one 12 and 1-oxa-2,7-diazaspiro[4,4]non-1en-6-one 13 in 38 and 20% de, respectively. On the other hand, reaction of 5 with N-phenylbenzonitrile imines 8 and 9, generated in situ from the corresponding hydrazonoyl chlorides 10 and 11, respectively, and Et 3 N, furnished racemic pyrrolo [3,4-c]pyrazoles 14 and 15 in 61 and 56% de, respectively. Cycloaddition of nitrile oxide 7, when performed in the presence of Et 3 N, led to pyrrolo [3,4-d]isoxazole 16 in 85% de.
Synthesis and structural investigation of some 1,4-disubstituted-2-pyrrolidinones
Arkivoc, 2005
A series of 1,4-disubstituted 2-pyrrolidinones was synthesized by condensation of 1-aryl-4hydrazinecarbonyl-2-pyrrolidinones with aromatic aldehydes, acetone, 2-butanone, and 2,4pentane-dione. Most of the reaction products have isomers owing to the amide and azomethine structural units in their molecules. Computer molecular modeling was used to study individual features of each isomer. The structures of the synthesized compounds were unambiguously elucidated by combining IR, mass, 1 H, and 13 C NMR spectroscopy on the basis of the theoretical characteristics derived from molecular modeling. In this work the NMR spectra of the studied compounds 3-9 revealed a successful choice of the representative examples and good support for the explication of the peculiarities of s-cis and s-trans isomers formed in amides by the existence of E/Z-configurations in azomethine fragments using solvents of different polarity. Data for the complete NMR assignments are presented.
A new asymmetric approach toward 5-substituted pyrrolidin-2-one derivatives
Tetrahedron, 1998
The condensation between a chiral 2-silyloxypyrrole and either achiral or chiral formyl cation equivalents has been studied. The methodology has allowed to build-up 5-substituted pyrrolidin-2-one derivatives with a stereocontrol from good to excellent. The chiral auxiliary located on the silyloxypyrrole showed an intrinsic good level of diastereoface discrimination at C-5. However, the use of a 2-methoxy-3-tosyl-oxazolidine as chiral formylating agent
Synthesis of Pyrrolidinols by Radical Additions to Carbonyls Groups
Proceedings
Radical cyclizations represent powerful synthetic strategies for the assembling of heterocycles. Most radical cyclizations are based on the addition to C C double or triple bonds. On the contrary, the addition to C O double bonds is rarely reported, since it proceeds reversibly due to the formation of thermodynamically unfavorable alkoxy radicals. Herein we report our attempts to construct substituted pyrrolidin-3-ols by tin-mediated radical cyclization of 5-phenylseleno-3-aza-pentanals. These rings are widely represented in natural products and drug candidates with various biological activities.
Synthetic studies of some Pyrrolidine-2,3-dione type compounds / Nurul Shulehaf Mansor
2014
Nitrogen containing heterocycles have attracted the interest of many research groups because they are widely found in nature as well as in pharmaceutical products. However, the syntheses of pyrrolidine-2,3-dione are rarely reported. In this study, 2,3- dioxo-4-carboxy-5-(substituted)pyrrolidines were synthesized to be potential intermediates for bioactive compounds. The key step in the synthetic strategy towards pyrrolidine-2,3-dione was the multicomponent reactions (MCR’s) using sodium diethyl oxalacetate, various amines and aldehydes as the starting materials. Using this protocol, a series of 2,3-dioxo-4-carboxy-5-(aromatic or aliphatic)pyrrolidines were successfully produced in moderate to good yields. In similar investigation, a chiral amine, (^-phenyl ethyl amine was employed in order to confirm the stereochemistry of the functionality at the C-5 position of the pyrrolidine skeleton. Compound pyrrolidine-2,3-dione was then used as the intermediate for a few chemical transformat...
Pyrrolidines: Priveleged Structure in Bioactive Molecules and Synthesis
International Journal for Research in Applied Science and Engineering Technology, 2017
Pyrrolidines constitute an important structural motif in natural and designed biologically active molecules. In addition, these heterocycles can be used for pharmaceutical purposesand ligands of transition metal catalysts.Pyrrolidines are also used as an effective chiral controller in various organic asymmetric transformations and are also being utilized in the synthesis of unnatural oligomers as scaffolds for various biological applications such as antidiabetic, anticancer, antimalarial, antiviral, antimicrobial, anti-inflammatory and antibacterial activities. Consequently, the efficient synthesis of these heterocycles has been received significant attention and different strategies for their syntheses have been developed. Among all the methods for the synthesis, the [3+2] cycloaddition of azomethineylides with substituted olefins is a most powerful method to rapidly obtain highly substituted pyrrolidine rings. It is intended to present a brief description of the methods for the synthesis and biological activities of pyrrolidine derivatives.