Diphenyldiazomethane reactions

The reactions of dichlorocarbene with morpholine and piperidine enamines derived from cyclopentanone and cyclohexanone have been reported to lead to ring expanded and a-chloromethylene ketone products (355,356). Similarly a-chloro-a, -unsaturated aldehydes were obtained from aldehyde derived enamines (357). Synthesis of aminocyclopropanes (353,359) could be realized by the addition of diphenyldiazomethane (360) and the methylene iodide-zinc reagent to enamines (367). 

The reaction of phosphoric acid with diphenyldiazomethane in dioxane gives the triphosphate. 

Other thietane derivatives have been obtained by isomerization of nitrogen-containing heterocycles. The reaction of an acyl isothiocyanate (RCONCS) with diphenyldiazomethane gave 20 and this isomerized in solution to the tetraphenyl-3-thietanone 21 <96BSB253>. Additionally, the isoxazolidine 22 was converted into 23 by the action of trimethylsilyl iodide and zinc iodide <96H1211>. 

The reaction of 1 with diphenyldiazomethane resulted in the hydrogenation of the >C=N=N unit to form the hydrazonato ligand, which is found T -N,N bonded to the metal [198, 199]. 

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. 

Reactions with Diphenyldiazomethane, Isocyanides, Benzonitrile, and tert-Butylphosphaacetylene... 

EPR studies of diphenylmethylene and a number of other arylmethylenes have indicated that these carbenes have triplet ground states.<30) Photolysis of diphenyldiazomethane in olefin matrices results in the formation of triplet diphenylmethylene, which undergoes primarily abstraction reactions with the olefins. Cyclopropanes are produced as minor products. 

A similar reaction with diphenyldiazomethane gives phosphabicyclohexene 102 exclusively by elimination of nitrogen atom from initial cycloadduct 101 (Scheme 31) [105],... 

Suggestive evidence for the protonation of diphenylcarbene was uncovered in 1963.10 Photolysis of diphenyldiazomethane in a methanolic solution of lithium azide produced benzhydryl methyl ether and benzhydryl azide in virtually the same ratio as that obtained by solvolysis of benzhydryl chloride. These results pointed to the diphenylcarbenium ion as an intermediate in the reaction of diphenylcarbene with methanol (Scheme 3). However, many researchers preferred to explain the O-H insertion reactions of diarylcarbenes in terms of electrophilic attack at oxygen (ylide mechanism),11 until the intervention of car-bocations was demonstrated by time-resolved spectroscopy (see Section III).12... 

The elusive diazoalkenes 6 and 14 are unlikely to react with methanol as their basicity should be comparable to that of diphenyldiazomethane. However, since the formation of diazonium ions cannot be rigorously excluded, the protonation of vinylcarbenes was to be confirmed with non-nitrogenous precursors. Vinyl-carbenes are presumedly involved in photorearrangements of cyclopropenes.21 In an attempt to trap the intermediate(s), 30 was irradiated in methanol. The ethers 32 and 35 (60 40) were obtained,22 pointing to the intervention of the al-lylic cation 34 (Scheme 10). Protonation of the vinylcarbene 31 is a likely route to 34. However, 34 could also arise from protonation of photoexcited 30, by way of the cyclopropyl cation 33. The photosolvolysis of alkenes is a well-known reaction which proceeds according to Markovnikov s rule and is, occasionally, associated with skeletal reorganizations.23 Therefore, cyclopropenes are not the substrates of choice for demonstrating the protonation of vinylcarbenes. 

Alkoxyallenes react with diazomethane at the terminal C=C bond to give 4-methy-lenepyrazoline 87, whereas the reaction with diphenyldiazomethane affords 3-methy-lenepyrazoline 88 [85],... 

Benztropine Benztropine, 3-(diphenylmethoxy)tropane (10.2.6), is synthesized by the reaction of tropin and diphenyldiazomethane [38],... 

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

Thermal reaction of 5-R-5-R -l,2,3,4,5-tetrathiagermolanc (338) (R = mesityl, R = 2,4,6-[(Mc3 Si)2CH]3CeH2) with diphenyldiazomethane gives three unusual heterocycles, the 1,3,4,2-tri-thiagermolane and the l,2,4,5-tetrathia-3-germa- and l,3,4,5-tetrathia-2-germacyclohexanes <91TL6143>. 

The preparation of thiiranes is most conveniently performed in solution. However, there are also protocols reported for reaction in the gas and solid phase. By using diazo and thiocarbonyl compounds in ether as solvent, both alkyl and aryl substituted thiiranes are accessible. As indicated earlier, aryl substituents destabilize the initially formed 2,5-dihydro-1,3,4-thiadiazole ring and, in general, thiiranes are readily obtained at low temperature (13,15,35). On the other hand, alkyl substituents, especially bulky ones, enhance the stability of the initial cycloadduct, and the formation of thiiranes requires elevated temperatures (36 1,88). Some examples of sterically crowded thiiranes prepared from thioketones and a macro-cyclic diazo compound have been published by Atzmiiller and Vbgtle (106). Diphenyldiazomethane reacts with (arylsulfonyl)isothiocyanates and this is followed by spontaneous N2 elimination to give thiirane-2-imines (60) (107,108). Under similar conditions, acyl-substituted isothiocyanates afforded 2 1-adducts 61 (109) (Scheme 5.23). It seems likely that the formation of 61 involves a thiirane intermediate analogous to 60, which subsequently reacts with a second equivalent... 

Spirocychc oxazohnes 311 are produced in 37-67% yield from acylisothio-cyanates 309 and an excess of diphenyldiazomethane 310. ° The proposed mechanism for product formation is indicated in Scheme 8.86. The reaction has also been demonstrated for 2-diazofluorene. There are no reports for aliphatic diazo compounds. 

Photolysis of diphenyldiazomethane in MeCN solution in the presence of sufficient 84 yields benzophenone in >90% yield and tetramethyipiperidine in equimolar amounts. A similar photolysis with 4-hydroxy-TEMPO (84, X = OH) gives benzophenone and ether (85) in 16 1 ratio, indicating that attack at the nitroxide center predominated even though it is more hindered than the OH group. In the case of cyclohexanol, which is used as a reference substrate for 4-hydroxy-TEMPO, the reaction with DPC gives >90% yield of the expected ether. ... 

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