1,3‐dipolar cycloaddition of diphenylnitrilimine to substituted dihydro‐3‐methylene‐2(3H)‐furanones

Abstract

Substituted 4,5-dihydro-3-methylene-2(3H)-furanones 1 react as dipolarophiles with diphenylnitrilimine to give the corresponding spiro[furan-pyrazo1in)ones 2. From the compound la, 1,3-diphenyl-?-oxa-l,2-diazaspiro[4.4]non-2-en-6one (2a) is formed. In the other cases, a primarily formed cycloadduct undergoes rearrangement during the reaction to the bicyclic compound 5. Thus, addition of diphenylnitrilimine to (E)-lb, (Z)-lb and (E)-lc leads to compound 5b, whereas reactions of (E)-or (Z)-lf and (E)-lg give the corresponding compound 5f and 5g, respectively. The structure of 5 b was determined by X-ray analysis. Labeled methyl formate (H13C02CH3) was used for labeling the methylene carbon atom in 4,5-dihydro-3-(p-tosyloxymethylene)-2(3H)-furanone [(E)-lb] in order to ascertain the structure of the intermediate cycloadduct as well as the pathway of the consecutive rearrangement.

Study on regioselective synthesis of bioactive bis-spiropyrazolines using molecular orbital calculations

“…The most developed phenomenon for the synthesis of these compounds depends mainly on cycloaddition reaction to exocyclic double bonds [5][6][7][8][9]. 1,3-Dipolar cycloaddition reactions are considered the most successful process for the construction of five-membered ring containing spiro and bis-spiro-compounds due to high regioand stereo-selective properties of these reactions [10,11].…”

Synthesis and crystal structure determination of two dispiro compounds from laboratory x‐ray powder diffraction data

“…The most developed procedure for the synthesis of these compounds depends on a cycloaddition reaction to exocyclic double bonds [7][8][9][10]. Due to their high regio-and stereoselective properties, nitrilimines are considered very reactive 1,3dipoles and have been widely used for construction of numerous spiro-compounds [11][12][13][14]. Here, we report on syntheses and crystal structure analyses of two new dispiro compounds, 1,3,4,8,10,11-Hexaphenyl-13-methyl-1,2, 8,9,13-pentaazadispiro[4.1.4.3]tetradeca-2,9-dien-6-one (3a) and 4,11-Bis(4-methoxyphenyl)-13-methyl-1,3,8,10-tetraphenyl- 1,2,8,9,13-pentaazadispiro-[4.1.4.3]tetradeca-2,9-dien-6-one (3b).…”

DOUBLE 1,3-DIPOLAR CYCLOADDITION OF 2,6-BIS(ARYLMETHYLIDENE)-CYCLOHEXANONES: A NOVEL ENTRY INTO THE SYNTHESIS OF 2′,6′-BIS-SPIRO(1-N-METHYL-4-ARYL-PYRROLIDINE)CYCLOHEXANONES

“…[2][3][4][5][6] Spiro compounds represent an important class of naturally occurring substances characterized by highly pronounced biological properties. [7][8][9] 2,6-bis(Arylmethylidene)cyclohexanones have also drawn much attention due to their important pharmacological properties.…”