Nitrenes carbonyl,

A series of Ru-Co mixed-metal nitride and nitrene carbonyl clusters 230-236 was synthesized from the interactions of [Ru3(/x-H)2(/X3-NOMe)(GO)9] with mononuclear cobalt reagents such as [Gp Go(GO)l2] and [Gp Go(GO)2]. The alkyne derivative [Ru3(/X3-NOMe)(/X3-77 -PhG2Ph)(GO)9] has also been used. It is interesting to observe the formation of 237,... 

It has been shown that one can successfully plan and carry out syntheses by incorporating either fluorine or parahalogen substituent groups in the chemistry of certain functional groups including carbenes, nitrenes, carbonyls, thiocarbonyls, selenocarbonyls, tellurocarbonyls, ketenes, thioketenes, sulfines, isocyanates, and sulfinylamines. In certain cases a decrease in stability is observed upon going fi-om F to CF3 and CF3S, while in other cases the instability of all derivatives precludes a... 

Reductive carbonylation of nitro compounds is catalyzed by various Pd catalysts. Phenyl isocyanate (93) is produced by the PdCl2-catalyzed reductive carbonylation (deoxygenation) of nitrobenzene with CO, probably via nitrene formation. Extensive studies have been carried out to develop the phosgene-free commercial process for phenyl isocyanate production from nitroben-zene[76]. Effects of various additives such as phenanthroline have been stu-died[77-79]. The co-catalysts of montmorillonite-bipyridylpalladium acetate and Ru3(CO) 2 are used for the reductive carbonylation oLnitroarenes[80,81]. Extensive studies on the reaction in alcohol to form the A -phenylurethane 94 have also been carried out[82-87]. Reaction of nitrobenzene with CO in the presence of aniline affords diphenylurea (95)[88]. 

From N-oxides of aromatic bases oxaziridines were obtained only at very low temperatures, but oxaziridines were often postulated as intermediates in the photoconversion of such N-oxides (Section 5.08.3.1.2). Isolation of the more stable photoisomers of nitrones also causes some problems due to their thermal and photochemical instability leading to acid amides, e.g. (69TL2281), or, by fragmentation, to carbonyl compounds and products of stabilization of nitrenes, e.g. from (260) (69ZN(B)477). 

N-benzylaniline with phosgene, and then with sodium azide to produce carbonyl azide 52. On heating, nitrogen is evolved and a separable mixture of nitrene insertion product 53 and the desired ketoindazole 54 results. The latter reaction appears to be a Curtius-type rearrangement to produce an N-isocyanate (54a), which then cyclizes. Alkylation of the enol of 54... 

FIGURE 7.10 Formation of the succinimido ester of IV-succinimidoxycarbonyl-P-alanine by reaction of three molecules of IV-hydroxysuccinimide (HONSu) with one molecule of dicy-clohexylcarbodiimide.25 The first molecule (N1) reacts to form the O-succinimido-isourea. The second molecule (N2) ruptures the ring by attack at the carbonyl, generating a nitrene that rearranges to the esterified carboxyalkyl isocyanate. The third molecule (N3) attacks the carbonyl of the latter. R3 = R4 = cyclohexyl SuN- = succinimido. 

The IR spectrum of the effusion gives a strong absorption peak at lT Ocm due to v(C=0) of carbonyl group. This absorption indicates that the aziridine was oxidized on the silicagel surface. Because of such a fact, silicagel can not be used for the analysis of the reaction products of aromatic nitrene with unsaturated olefines. The present experiment, therefore, was repeated by replacing silicagel with alumina. 

In 1987, Nitta reported the formation of an unexpected vinylketene complex from the reaction of an azido-substituted cyclopropene with diiron nonacarbonyl.104 They had previously investigated the chemical behavior of the complexed nitrene intermediates that result from the reaction of organic azides and iron carbonyls113 and were interested in replicating the thermal isomerization of 3-azido-l,2,3-triphenylcyclopropene (163) into 4,5,6-triphenyl-l,2,3-triazine using a metal carbonyl-promoted re-... 

A very reactive nitrogen atom is required to convert benzenes or naphthalenes into pyridines, and there are a number of such reactions which involve nitrenes or nitrenoid species. A number of substituted benzenes have been treated with sulfonyl diazide or carbonyl diazide and moderate yields of pyridines recorded (27CB1717). Thus p-xylene gives 2,5-dimethylpyridine there is no indication of the fate of the carbon atom which is lost. More controlled reaction is possible in intramolecular insertions. The examples in which o-nitrotoluene is converted into a derivative (759) of 2-acetylpyridine, and where 2,3-diazidonaphthalenes give 3-cyanoisoquinolines (760) are quoted in a review (81 AHC(28)231>. 

Nanosecond time resolved infrared (TRIR) spectroscopy has recently become available to physical organic chemists. This spectroscopy is an attractive tool for studying carbonyl nitrenes. Such work is in progress in several laboratories ... 

The synthesis of metal-coordinated 1-azirines and the reactions of azirines induced by metals have opened a new area in the chemistry of this small ring heterocycle. Many of the reactions encountered bear resemblance to previously discussed thermally and photo-chemically induced reactions of 1-azirines. The reaction of a series of diiron enneacarbonyls in benzene results in coupling and insertion to give diimine complexes and ureadiiron complexes as well as pyrroles and ketones (76CC191). A mechanism for the formation of these products which involves initial 1,3-bond cleavage and generation of a nitrene-iron carbonyl complex as an intermediate was proposed. 

Insertion by nitrenes 2-55 Carbonylation of amines or nitro or nitroso compounds... 

Some four-electron capping units enter as such. This is the case for the many reactions forming/t3-sulfur ligands from elemental sulfur (103). It also holds for the triruthenium /i3-nitrene cluster 45, formed from Me3SiN3 and Ru3(CO)i2 (104). A versatile four-electron ligand is the acetylene moiety, which can add facially to M3 units as a two-center capping group, as found in the clusters 46, which can be obtained from trinuclear carbonyls of iron, ruthenium, and osmium (105, 106). 

Benzoyl nitrene 247 (R = Ph) generated by photolysis of benzoyl azide in the presence of carbonyl compounds affords 1,4,2-dioxazolines 248-251 (Scheme 34). Moderate yields are obtained upon irradiation at 254 nm, while better yields are obtained upon irradiation at 365 nm in the presence of a sensitizer, such as Michler s ketone, which diminishes the photo-Curtius side reaction of acylnitrene to isocyanate. With ethoxycarbonylnitrene 247 (R=—OEt) and acetone, compounds 251 and 252 are obtained the latter is possibly formed from acetone and the dipolar intermediate 252 <1995T7181>. In another report on reactions of chiral aroylnitrene 254, the obtained dioxazolines 255 do not show any diastereoselectivity, although the presence of a chiral auxiliary in the ortfe-position ensures its vicinity to the reaction center (Scheme 35) <2001S1125>. 

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