Kabula Ciamala

Spiroheterocycles from reaction of nitrones with methylene-γ-butyrolactones and some of their rearrangements

Cycloaddition of nitrones 1 with methylene-gamma-butyrolactones 2, 3 and 4 afforded spiroadducts 5, 6 and 7 with high selectivity. Mixtures of diastereoisomers were usually obtained, whose structures were established by 1H and 13C NMR spectroscopies or X-ray crystallography. Treatment of spiroadducts in acidic and alkaline media led to different, unexpected and novel rearrangements.

An Efficient One Pot Synthesis of New Indanopyrazoline and Indanopyrazole Derivatives

Synthesis of a series of novel fused pyrazolines and pyrazoles has been accomplished in good yields by regio- and diastereoselective 1,3-dipolar cycloaddition of enamines of indan-1-one 1a-c towards C-aryl-N-phenylnitrilimines 2d- f. The structure of the cycloadducts was elucidated by 1D and 2D NMR studies.

Reactivity Of Arylnitrile Oxides And C-Aroyl-N-Phenylnitrones With 3-Methylenedihydro-(3H)-Furan-2-One And Itaconic Anhydride

1,3-dipolar cycloaddition is a powerful route for the synthesis of five-membered heterocycles. The [3+2] cycloadditions of some alpha-methylene-gamma-buryrolactones, namely 3-methylenedihydro-(3H)-furan-2-one (1) and itaconic anhydride (2) were Studied. Their reactions with arylnitrile oxides (3) and Caroyl-N-phenylnitrones (7) proceed with complete regioselectivity. From a stereochemical point of view, the addition of arylnitrile oxides (3) leads to the unique spiroheterocycles (4-5). Actually, a single stereocenter is generated during the reaction. In the particular case of p-nitrophenylnitrile oxide (3d), only the diacidic form (10d) of the spiroheterocyle (5d) was isolated. In contrast, the addition of C-aroyl-N-phenylnitrones (7) produces a couple of diastereoisomers. since two stereocenters are generated simultaneously. Nevertheless, the reaction is regioselective and stereospecific leading also to the single spiroheterocycles (1920). The proposed stereochemistry of spiranic compounds (19d) and (20d) has been corroborated by two single crystal X-ray crystallographic analysis.

Reaction of 3-methylenedihydro(3H)furan-2-one with diazoalkanes: syntheses and crystal structures of spiranic cyclopropyl compounds

The (3+2) cycloaddition of diphenyldiazomethane (2) (1,3-dipole) with 3-methylenedihydro-(3H)furan-2-one (5) as dipolarophile leads to the spiranic cyclopropyl derivative 1,1-diphenyl-4-oxo-5-oxaspiro(2.4)heptane (8b).

The [3+2] cycloaddition of diphenyldiazomethane and ethyl diazoacetate with itaconic anhydride. A new access to spiranic cyclopropane derivatives

The reaction of itaconic anhydride 1 with ethyl diazoacetate 2 or diphenyldiazomethane 5 gave the expected spiroderivatives, which spontaneously rearranged; specifically, the adduct from 1 and 5 loses a dinitrogen molecule, yielding a spirocyclopropane related to the known 5-azaspiro[2.4]heptane-4,6-diones or 5-azaspiro[2.4]heptanes.

Reaction of 2‐Benzoyl‐1,2‐dihydroisoquinoline‐1‐carbonitrile Tetrafluoroborate with (Z)‐2‐Arylidene‐3(2H)‐benzofuranones – Access to Chromenopyrrole Derivatives

Spiro[pyrrole-3,2′-3(2H)-benzofuranones] 7 have been synthesized by [4+2] cycloaddition of 2-arylidene-3(2H)-benzofuranones with the 2-benzoyl-1,2-dihydroisoquinoline-1-carbonitrile tetrafluoroborates. In acidic medium or in refluxing DMF, the spiro compounds yield tetrasubstituted pyrroles or compounds derived from chromenopyrroles. The regio- and stereochemistry of the reaction was established by spectroscopic or X-ray analysis.

A convenient synthesis of novel spiroisoindolone γ-halobutyrolactones via halocyclization of γ-ethylenic acids

Abstract Paper Volume 78 , Issue 11 ( November, 1, 2009 ), Pages 2787-2798 Received, 1st July, 2009, Accepted, 3rd September, 2009, Published online, 7th September, 2009. DOI: 10.3987/COM-09-11787 Full Text HTML PDF (2.5MB) PDF with Links (1.1MB) A Convenient Synthesis of Novel Spiroisoindole γ -Halobutyrolactones via Halocyclization of γ Ethylenic Acids Mohamed M. Rammah, Mohamed Othman,* Kabula Ciamala, Michael Knorr, Carsten Strohmann, and Mohamed B. Rammah Laboratory of Organic Chemistry, URCOM, EA 3221, Faculty of Sciences and Techniques, University of Le Havre, 25 Rue Philippe Lebon, BP 540, F-76058 Le Havre Cedex, France Abstract γ-Ethylenic carboxylic acids are cyclized to spiroisoindolone γ-halomethylbutyrolactones, in the presence of NBS or NIS and K 2 CO 3 . The corresponding haloaspirobutyrolactones were isolated in high yields (57-95%). Graphical Abstract Keywords 1. Halolactonization 2. Spirocyclization 3. Spiroisoindole 4. Butyrolactone 5. Exocyclic Lactone mohamed.othman@univ-lehavre.fr

Stereochemical and electronic features of the [3 + 2] cycloaddition of pentafulvenes with acylnitrones

A series of mono- and di-substituted pentafulvenes 1–3 was reacted with aroylnitrones 4 to afford the corresponding fused bicyclic monoadducts 5–9, generally as a mixture of isomers. The stereochemistry of the addition reaction was established by 1D and 2D NMR spectroscopies or X-ray crystallography. Performance of theoretical calculations has been undertaken in order to rationalize the important differences in regioselectivity displayed by the reaction.