Diphenyldiazomethane, 1,3-cycloadditions with

Diphenyldiazomethane has also been used in 1,3-dipolar cycloadditions with 4-arylmethylene-5(47/)-oxazolones 670 to prepare gem-diphenyl-spirocyclopropane oxazolones 671." A number of 671 analogues were evaluated as antibacterial agents. " In addition, 671 derivatives were precursors for new 1-aminocyclopropanecarboxylic acid derivatives 672, for example, l-(benzoylamino)triphenylcy-clopropanecarboxylic acid 672 (R = Ar = Ph) (Scheme 7.211). 

Cycloaddition Reactions with Mesityl Azide, Diphenyldiazomethane, Isocyanides, and Benzonitrile... 

Surprisingly, in contrast to the reaction of the Si=P bond with mesityl azide, the reaction of 15a with diphenyldiazomethane resulted in the formation of the [2+l]-cycloadduct 35 (Scheme S).38 The bonding situation in 35 (Fig. 11) may be described in terms of a 7r-complex, by employing the Dewar-Chatt-Duncanson model, in which the Si=P bond acts as v donor and acceptor at the same time (Scheme 9). The corresponding [2+31-cycloaddition product 36 was generated only on thermal activation of 35. 

Scheme 31 [3+2] Cycloaddition of 2-acetyl [l,2,3]diazaphosphole with diphenyldiazomethane...

Less frequently applied are [3 + 2] and [2 + 2] cycloadditions of oxygen-substituted allenes [102-104], Battioni et al. described only a limited number of [3 + 2] cycloadditions of phenyloxy- and methoxyallene with diphenyldiazomethane (157) and the nitrile imine derived from diphenylhydrazonoyl chloride (159) (Scheme 8.40) [102], Both 1,3-dipoles exclusively attack the terminal C=C bond, furnishing cycloadducts 158 and 160. Padwa et al. reported [3 + 2] cycloadditions of methoxyallene 145 with two nitrones which afforded isoxazolidines in low yield [103]. 

With benzaldazine, a criss-cross-type cycloaddition takes place reaction with diphenyldiazomethane yields a bicyclic phosphirane (49) among other products <87CB597). 

Dipoles such as diazoalkanes PhC(R1)N2 undergo cycloaddition to fluoroalkyl ketones CF3COR2 to give A2-oxadiazolines (111) (78JA4260). Diphenylketene reacts in a similar manner with diphenyldiazomethane. 

The 4,5-dihydro-37/-l,2,3-diazaphosphole 34 produced by a [3+2] cycloaddition reaction of diphenyldiazomethane with a phosphaalkene is unstable and decomposes by extrusion of Na and formation of a new P-C bond yielding the phosphirane 35 (Scheme 14) <2001ZFA1241>. 

The reaction of diazoalkanes with acetylenes can give rise to cyclopropenes by two main routes. Some reactions involve an initial loss of nitrogen to generate a carbene which then adds to the acetylene (see Section 1.2.1.), but this section is concerned only with those reactions where the first step is a cycloaddition leading to formation of a 3//-pyrazole. Unlike the parallel series of reactions in the cyclopropane series, where the C-C double bond of the alkene requires activation by a suitable substituent or by strain. Under pressure even acetylene itself will react with diazoalkanes. For example, diphenyldiazomethane underwent addition in good yield and deazetization gave 3,3-diphenylcyclopropene (1). ... 

The first cycloaddition of sulfene to the C=N bond was reported by Staudinger and Pfenninger107, who showed that the reaction of diphenylsulfene, generated from diphenyldiazomethane and sulfur dioxide, gave a four-membered cyclic compound with benzylideneaniline (equation 118). 

Very active interest in a new addition reaction of aliphatic diazo compounds started in 1991 when WudPs group reported that diphenyldiazomethane forms diphenylmethanofullerene with buckminsterfullerene (C o Suzuki et al., 1991). Although this investigation showed that the reaction proceeds via the formation of a dihydro-pyrazole, i.e., in the mode of a 1,3-dipolar cycloaddition followed by an azo-extrusion, we shall discuss the syntheses of methanofullerenes in its entirety in the chapter on carbenes (Sect. 8.4) because Diederich s recent work (see review of Diederich et al., 1994b) shows that the methano bridge can also be obtained from a carbene. The question whether the dihydro-pyrazoles are intermediates or side-equilibrium products (see earlier in this section) is also open for the reaction of with diazoalkanes. 

Diphenylketene also reacts with diphenyldiazomethane to form the [3+2] cycloadduct 369. In this reaction, the C=0 bond of the ketene participates in the cycloaddition reaction. 

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