Mesitonitrile oxide

Diels-Alder reactions, 4, 842 flash vapour phase pyrolysis, 4, 846 reactions with 6-dimethylaminofuKenov, 4, 844 reactions with JV,n-diphenylnitrone, 4, 841 reactions with mesitonitrile oxide, 4, 841 structure, 4, 715, 725 synthesis, 4, 725, 767-769, 930 theoretical methods, 4, 3 tricarbonyl iron complexes, 4, 847 dipole moments, 4, 716 n-directing effect, 4, 44 2,5-disubstituted synthesis, 4, 116-117 from l,3-dithiolylium-4-olates, 6, 826 electrocyclization, 4, 748-750 electron bombardment, 4, 739 electronic deformation, 4, 722-723 electronic structure, 4, 715 electrophilic substitution, 4, 43, 44, 717-719, 751 directing effects, 4, 752-753 fluorescence spectra, 4, 735-736 fluorinated derivatives, 4, 679 H NMR, 4, 731 Friedel-Crafts acylation, 4, 777 with fused six-membered heterocyclic rings, 4, 973-1036 fused small rings structure, 4, 720-721 gas phase UV spectrum, 4, 734 H NMR, 4, 7, 728-731, 939 solvent effects, 4, 730 substituent constants, 4, 731 halo... 

The 1,3-dipolar cycloaddition of mesitonitrile oxide 575 to benzo[h]thiophene S-oxides 576 in non-stereoselective and both syn and anti adducts 577 are obtained674,675 (equation 366). 

When a C6D6 solution of the silylene-isocyanide complex 21 was treated with an equimolar amount of mesitonitrile oxide at room temperature, the blue color of 21 immediately disappeared, and the 29Si and 13C NMR spectra of the reaction mixture exhibited characteristic strong signals (8Si = 26.9, 8C = 184.3) assignable to those of compound 22a having a novel 1,2,4-oxazasilete ring system (Scheme 5). The oxazasilete 22a was not stable at ambient temperature, and... 

The formation of silaneselone 57 was evidenced by the trapping reaction with mesitonitrile oxide leading to the corresponding cycloadduct 58 and was also supported by the observation of a remarkably downfield 29Si chemical shift (8Si = 174) indicative of the Si=Se double bond of 57. Although this direct selenation of silylene 55 with an equimolar amount of selenium was not reproducible, the use of excess amount of elemental selenium resulted in the formation of a new cyclic diselenide, diselenasilirane 59, as a stable compound (8Si = -44 and... 

Better yields were obtained with the stable mesitonitrile oxide (343) which enables the cycloaddition at higher temperature (entry 3). In the reaction of 341... 

Methylmagnesium bromide (191) exerts a great influence on the stereoselectivity of the reactions between mesitonitrile oxide 10 and the Baylis-Hillman adducts 192. In the absence of a Grignard reagent, a mixture of isomers is formed in which compounds 194 are the main products. The presence of a Grignard reagent reverses the stereoselectivity (Scheme 9.59). When Fisera [107] performed these reactions under microwave irradiation, the reaction times decreased from days to less than 5 min without any loss of stereoselectivity for noncatalyzed cycloadditions, but with a small change in the stereoselectivity in the chelated reactions. 

Dipolar cycloaddition reactions occur with mesitonitrile oxide and tellones to afford oxatellurazole in good yield,25,245,248 while a triazene is formed with phenyl azide25 probably via detelluration of a telluratriazoline ring (Scheme 44). 

Nitrile oxides, RNCO, are derivatives of fulminic acid (R = H). They can be named as fulmido-substituted parent molecules, but usually their names are derived from corresponding nitriles, for example, benzonitrile oxide, mesitonitrile oxide, thiophene-2-carbonitrile oxide. 

On the basis of previously published data (235), concerning thermal rearrangement of 68 (R = Ph and mesityl) to furo[3,2-c]pyridine derivatives, reactions of mesitonitrile oxide and triphenylacetonitrile oxides were carried out (o-ChCehU, 170°C, 5 days) leading to compounds 72 (R = 2,4,6-Me3C6H2, PI13C) in 7% and 21% yields, respectively (Scheme 1.20) (234). 

There are a few communications concerning cycloadditions of nitrile oxides to unsaturated oxa and aza cage systems. Benzo- and mesitonitrile oxides RCNO give, with five substituted 7-oxanorbomenes 106, mixtures of the corresponding exo-adducts 107 and 108 in nearly quantitative yields. No traces of compounds resulting from the endo-face attack was detected (274). Substituents at positions 5 and 6 of 106 render the process highly regioselective. 

Mesitonitrile oxide and acridine (1 2 ratio) react site- and regioselectively to give mono-cycloadduct 127. The reaction of the same reagents in a 10 1 ratio afforded the mono-cycloadduct 127, and the bis-cycloadduct 128 with the opposite regiochemistry to that of the mono-cycloadduct (288). 

Reactions of 2,3-dihydro-17/-1,4-diazepines with mesitonitrile oxide proceed with site- and regiospecific 1,3-dipolar cycloaddition leading to bis[ 1,2,4] oxadiazolo[l,4]diazepine derivatives 160 (326). Of the three compounds 160 only the one with R = R = Ph is formed with trails arranged substituents. The two other products (R = R = Me and R = Me, R = Ph) are mixtures of diastereoiso-mers. The heterotricyclic 6,1 Oa, 11,11 a-tetrahydro-5//-bis[ 1,2,4]oxadiazolo[4,5-d 5 -g][, A diiazeipm.e structure 160 of the obtained bis-adducts indicates that the hetero double bonds are much more reactive than the olefinic ones. No evidence for the formation of monoadducts was obtained. 

Reactions of 1,2-diazepines with nitrile oxides are sometimes difficult to elucidate because they give mixtures (328) or unexpected products. Thus, reactions of 3-methyl- and 3,7-dimethyl-1,2-diazepines with mesitonitrile oxide leads to 5,10-dioxa-l,2,4,ll-tetrazatricyclo[7,3,l,02,6]trideca-3,7,l 1-triene derivatives 162 (R = H, Me, respectively) (329). Such structures were determined by X-ray diffraction studies (330). 

Mesitonitrile oxide, but not benzonitrile oxide, adds to aza-analogs of phenan-threne, viz., benzo[/z]quinoline, 1,10-, 1,7-, and 4,7-phenanthrolines to give low yields of mono-cycloadducts at the C(5)=C(6> bond. Only 4,7-phenanthroline gave minor products, of which one the bisadduct 167 was isolated in approximately 7% yield. Phenanthridine reacts with two nitrile oxides but affords phenanthridin-6-one rather than a cyclo-adduct (336). 

Benzonitrile oxide and mesitonitrile oxide undergo 1,3-dipolar cycloaddition reactions with 1,3,5-triphosphinines under mild conditions to afford fused heterocyclic compounds (Scheme 1.33), for example, 192 and 193. Oxaphosphazoles and oxadiphospholes have become accessible by thermal fragmentation reactions of such fused heterocyclic compounds (358). 

Kinetically stabilized germanothiones Tbt(Tip)Ge = S, Tbt(Dis)Ge = S and germanoselones Tbt(Tip)Ge = Se, Tbt(Dis)Ge = Se [Dis = bis(trimethylsilyl) methyl, Tbt = 2,4,6-trisbis(trimethylsilyl)methylphenyl, Tip = 2,4,6-tris(iso-propyl)phenyl], have been synthesized and have shown to enter 1,3-dipolar cycloaddition reactions with mesitonitrile oxide (361). 

On heating at 95°, in the presence of tropone, ferf-butylphosphaacetylene, P=C-Bu formed along with the tetracyclic adduct 202 gave 5% of tetraphos-phasemibullvalene 203. The latter reacted with mesitonitrile oxide to give oxaphosphazole 204, which was characterized by X-ray crystallography (365). 

On treatment with a base such as NaOMe or even LLAIH4, mono-cycloadducts of mesitonitrile oxide and polycyclic aromatic hydrocarbons have been cleaved to yield the corresponding oximes, which are oxidized to ketones by the Dess— Martin method. The same ketones have been obtained by reductive ring opening of the mono-cycloadducts with Raney Ni (438). 

Electroactive 3-(N-phenylpyrazolyl)fullereno[l,2-r/]isoxazolines have been synthesized by using 1,3-dipolar cycloaddition of pyrazole nitrile oxides, generated in situ, to Cgo at elevated temperature or microwave irradiation. The cyclic voltammetry measurements show a strong donor pyrazole ring, and a better acceptor ability of the fullerene moiety than the parent C60 (538). Treating fullerene Cgo with mesitonitrile oxide in toluene gives fullerene-nitrile oxide adduct, which is supposed to be useful for electrical and optical components (539). 

Like their stable heavy ketone congeners, the germanetellones Tbt(R)Ge = Te underwent [2 + 3] and [2 + 4] cycloadditions with mesitonitrile oxide and 2,3-dimethyl-l, 3-butadiene, respectively144 (Scheme 39). 

A study of the regioselectivity of the 1,3-dipolar cycloaddition of aliphatic nitrile oxides with cinnamic acid esters has been published. AMI MO studies on the gas-phase 1,3-dipolar cycloaddition of 1,2,4-triazepine and formonitrile oxide show that the mechanism leading to the most stable adduct is concerted. An ab initio study of the regiochemistry of 1,3-dipolar cycloadditions of diazomethane and formonitrile oxide with ethene, propene, and methyl vinyl ether has been presented. The 1,3-dipolar cycloaddition of mesitonitrile oxide with 4,7-phenanthroline yields both mono-and bis-adducts. Alkynyl(phenyl)iodonium triflates undergo 2 - - 3-cycloaddition with ethyl diazoacetate, Ai-f-butyl-a-phenyl nitrone and f-butyl nitrile oxide to produce substituted pyrroles, dihydroisoxazoles, and isoxazoles respectively." 2/3-Vinyl-franwoctahydro-l,3-benzoxazine (43) undergoes 1,3-dipolar cycloaddition with nitrile oxides with high diastereoselectivity (90% de) (Scheme IS)." " ... 

Tetrathiametallolanes (343) <94PS(95-96)2i> are useful precursors of analogues of thio-ketones (343) which act as dipolarophiles in (3 + 2)-cycloaddition reactions to give, for example, (400) with mesitonitrile oxide. 

Enamines are known to undergo cycloaddition with nitrile oxides. However, 3-pyrrolidinothiophene with mesitonitrile oxide gave only the oxime (289) no isoxazoline could be detected (74RTC321). Whether an isoxazoline is an intermediate in the formation... 

The first example of a [2 + 4] cycloaddition of a thiophene 1-oxide seems to be the formation of a 1 1 mixture of the syn and anti isomers of 3-(2,4,6-trimethylphenyl)-8b-methylbenzo[6]thieno[2,3-[Pg.840]

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