Ethers ethyl vinyl, reaction with lead

An intermolecular reaction of N-sulfonyl-l,2-propadiene 250 with ethyl vinyl ether leading to tetrahydropyridine 254 was observed [131]. 

Therefore, most probably, the formation of chrysenes 246 from 2-benzopyrylium salts occurs via the process of a-1 dimerization. At the same time, one cannot exclude the action of anhydrobase 267 as dieno-phile, which leads to its addition to positions 1 and 4 of the initial 2-benzopyrylium cation by analogy with [4 + 2] cycloadditions in reaction with ethyl vinyl ether (Scheme 14) (cf. Section III,D,1). 

The first examples of ortho cycloaddition can be found in a U.S. patent of Ayer and Buchi [1], Benzonitrile and 2-methylbut-2-ene are reported to yield 7,8,8-trimethylbicyclo[4.2.0]octa-2,4-diene-l-carbonitrile upon irradiation under nitrogen with a mercury resonance arc. Similar reactions, all leading to derivatives of bicyclo[4.2.0]octa-2,4-diene-l-carbonitrile occurred when benzonitrile was irradiated in the presence of 2,4,4-trimethylpent-l-ene, ethyl vinyl ether, vinyl acetate, methyl vinyl ketone, and methyl acrylate. The addend pairs para-tolunitrile/oct-l-ene, ort/m-dicyanobenzene/2-methylbut-2-ene, para-dicyanobenzene/but-l-ene, 2,3-dimethylbenzonitrile/propene, and 3,4,5-trimethylbenzonitrile/ethene likewise produced ortho photocycloadducts. 

The two exceptions to the ortho-para rule are the reactions between an X-substituted diene and an X-substituted dienophile. The frontier orbitals in Fig. 6.27, taken from Fig. 6.22, indicate that the preferred combination, whichever pair of frontier orbitals and whichever diene, 1-substituted or 2-substituted, is taken, will lead to the meta adduct. Neither frontier orbital interaction is between orbitals close in energy (> 11 eV in all combinations), with the result that the reaction can be expected to be very slow, and is in practice exceedingly rare. One example is the combination of the (vinylogous) 2-X-substituted diene 6.158, derived from the benzcyclobutene by electrocyclic ring-opening, and ethyl vinyl ether 6.159. Although not usefully regioselective, the reaction does take place, assisted by the aromatisation of the diene, and the meta adduct is the major product. 

High-pressure absorption spectroscopy is widely applicable for studying the reactivity and the selectivity of chemical transformations. Some results are shown concerning the investigation of the //ctc/ o-Diels-Alder reactions between the enamine carbaldehyde 1 and enamino ketones 2 with ethyl vinyl ether 3, which lead to the diastereomeric dihydropyrans 4-1-5 and 6 + 7, respectively. Scheme 6.7-1 (Buback et al., 1988 Buback et al., 1989). 

Dipolar Cycloadditions. 1,3-Dipolar cycloadditions provide a powerful method for the synthesis of five-membered heterocyclic rings. The use of (5,5)-r-Bu-box in combination with Cu(OTf)2 as catalyst for the reaction of a nitrone with ethyl vinyl ether leads to the products in 93% yield (eq 23). The diastere-oselectivity is exo-selective, as the product was obtained in an endo/exo ratio of 83 16. A change of the counterion in the cata-... 

IntrodnclUm offkHctionmlized oagmlar methyl groups. The reaction of ethyl vinyl ether with 10-methyl-A -2-octalol (1) catalyzed 1 mercuric acetate in a sealed Carius tube for 12 hr. at 200° gives 9-formylmethyl-10-methyNA -octalin (2, 85% yield) together with some dienes (3,15 % yield). Use of phosphoric acid leads only to the dienes (3). The one-step procedure involves formation of the vinyl ether followed by Claisen... 

Fischer-type carbenes are known as potential carbene transfer reagents to electron-rich and electron-deficient alkenes. Little is known about the chemistry of carbene complexes with silicon substituents at the carbene C-atom, whereas complexes with germanium, tin, or lead have not yet been prepared. The tungsten-carbene complexes 6 react with an excess of ethyl vinyl ether to give l,2-diethoxy-l-(trialkylsilyl)cyclopropanes 7." Only the f-isomers were formed and similar results can be achieved by using the corresponding molybdenum or chromium complexes. On the other hand, no reaction takes place with 2,3-dihydrofuran or ethyl ( )-but-2-enoate. ... 

The kinetic data from phosphine dissociation studies and reaction with ethyl vinyl ether fit the classical dissociative exchange catalysis model very well [101]. Examination of this model leads to the conclusion that there are two main factors controlling the activity of these catalysts the rate of phosphine dissociation and the metathesis activity of the phosphine-dissociated species (Scheme 6.26). 

A possible approach to four-membered ring compounds (grandisol is cited particularly in the publication) consists of the treatment of the dihydropyran 314 (product of the reaction between methacrolein and ethyl vinyl ether) with triiso-butylaluminum, leading to the alcohol 315 (R = CH2OH), oxidation of which gave the aldehyde 315 (R = CHO). Although the latter readily reverts to the starting material 314, it can be isolated and used (especially in the absence of transition metals). 

As in the OH-initiated oxidation of vinyl ether, the reactions of O3 with the same vinyl ethers lead mainly to formation of formates (molar yields of (70-90)%) and formaldehyde (molar yields of (20-10)%). Figure 2 shows an example of the concentration-time profiles of the reactants and products for the reaction of O3 with ethyl vinyl ether (C2H50CH H2). For methyl vinyl ether, hydroperoxymethyl formate and methanol were also observed as produets (Klotz et ai, 2004). 

The hetero-Diels-Alder reaction with inverse electron demand is an attractive route for the synthesis of 3.4-dihydro-2//-pyrans. Enone 7, esterified with D-mandelic acid as chiral auxiliary, adds to ethyl vinyl ether (8) to give a 2 1 mixture of 9 and 10 [d.r. (2S,4S) (2RAR) 67 33]1. The enone 11 requires high pressure to add to the much less reactive enol ether 12, yielding a 2 3 mixture of 13 and 14 [d.r. (2S, 3S,45 )/(21 ,37 ,4/ ) 40 60]8. The introduction of the additional stereogenic center in the enone 15 leads to a substantially improved diastereofacial selectivity, and adducts 16 and 17 are obtained as a 1 10 mixture [d.r. (2S.4S) (2RAR) 9 91]9. 

Gas-phase reaction of 2 with ethyl vinyl ether leads to observation of the high-resolution chemiluminescence spectrum of formaldehyde, arising from thermal decomposition of the dioxetan (82) shown in Scheme 13.136... 

Irradiation at 254 nm in the charge-transfer band of the complex between diethyl ether and oxygen leads to several products (with the quantum yields given) H2Oa (0.24), 1-ethoxyethyl hydroperoxide (0.04), ethyl acetate (0.26), acetaldehyde (0.18), ethanol (0.18), ethyl formate (0.04), methanol (0.035), formaldehyde (0.005), and ethyl vinyl ether (0.013).197 The primary process appears to be electron transfer from ether to oxygen, as shown in reaction (37). Reaction with... 

Precaution Corrosive to iron, steel, brass, copper, lead explosive reaction with ethyl vinyl ether incompat. with hydrogen fluoride, alkalis, amines, vinyl ethers reacts violently with water Hazardous Decomp. Prods. Heated to decomp., emits toxic fumes of SO,... 

Superelectrophilic properties of nitroarenes are retained when mie of the furoxan rings in NBDF is replaced with electron-deficient isoxazole [124] or pyridine fragments [125]. As in case of NBDF, the reactions of these fused nitroarenes with ethyl vinyl ether were found to lead to the correspruiding benzoxazine N-oxides 143 and 144 condensed with heterocyclic rings (Scheme 72). 

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