ChemInform Abstract: 1,3‐Dipolar Cycloadditions. Part 14. Highly Selective Cycloadditions of C,N‐Diaryl Nitrones to Diethyl Aryl Methylene Malonates.

Abstract

Isoxazole derivatives R 0240 1,3-Dipolar Cycloadditions. Part 14. Highly Selective Cycloadditions of C,N-Diaryl Nitrones to Diethyl Aryl Methylene Malonates. -1,3-Dipolar cycloaddition of nitrones (I) to arylmethylenemalonates (II) occurs with complete regio-and diastereoselectivity to furnish trans-3,5-diarylisoxazolidines (III). This is in contrast to nitrone cycloaddition reactions with cinnamic acid derivatives, which provide two diastereomeric cycloadducts. -(BANERJI*, A.; SENGUPTA, S.; NAYAK, A.; BISWAS, P. K.; BHATTACHARYA, B.; DASGUPTA, S.; SAHA, R.; PRANGE, T.; NEUMAN, A.; Indian J.

[3+2] Cycloadditions: Part XXXIV: Further Investigations of Cycloadditions of C,N-Diaryl- and C-Aryl-N-methyl Nitrones to α,β-Unsaturated Esters

“…The arylidene malonate dipolarphiles (18,19,20) were prepared by standard experimental procedures [24][25][26] from diethyl malonates by condensation with the appropriate aromatic aldehydes in presence of piperidine in benzene solution. The structural integrities of the dipolarophiles were confirmed by IR and NMR spectra.…”

“…The 32CA of four differently substituted nitrones (1)(2)(3)(4) to various substituted methyl E-cinnamates are reported (Scheme-I). Additionally, the reaction of C-(4-nitrophenyl)-N-(4′-chlorophenyl) nitrone (14) with 8, reported earlier [19], was repeated to obtain further amounts of the resultant cycloadducts 15a-c.…”

“…carboxamide, carboxylate ester, keto-and nitro. The regio-and stereoselectivities of these reactions have been studied and in several instances, the course of reactions analyzed by computational studies [1,2,9,[11][12][13][14][15][16][17][18][19][20][21].…”

“…32CA reactions of C-aryl-N-methyl nitrones with diethyl arylidene malonates were investigated for the first time. We had earlier investigated the 32CA of C,N-diaryl nitrones to arylidene malonates [19]; a remarkable increase in regioand stereoselectivity compared to cinnamic acid esters was observed leading to the exclusive formation in the uncatalyzed reactions of trans-3,5-diaryl-4,4-dicarbethoxy isoxazolidines in nearly quantitative yields. It was of interest to us to find out whether there would be any changes in reactivity and selectivity if C-aryl-N-methyl nitrones were reacted.…”

Simple and efficient routes to substituted oxazolidine and spiro-oxindole systems by one-pot synthetic strategies

“…In some cases cycloaddition of azomethine ylides with carbonyl double bond was reported as a side reaction, and not as a synthetic procedure on its own [31]. Our longstanding interest in 1,3-dipolar cycloaddition [41][42][43][44][45] led us to turn our attention on the direct synthesis of oxazolidine moieties by cycloaddition of non-stabilised azomethine ylides with carbonyl compounds. Orsini et al [32] and Felluga et al [33] had reported direct cycloaddition of azomethine ylides with carbonyl compounds.…”