2-Vinyl-l,3-dioxolan

To overcome this drawback, we studied the arylation of diethyl 2-vinyl-[l,3]-dioxolane-4,5-diacetate 2 with several bromo polyaromatic and heteroaromatic substrates (Table 21.1 and Scheme 21.4). In parallel, the Heck coupling of several vinyl dioxolane derivatives with aryl bromides was studied in the presence of homogeneous catalysts (Table 21.1). 

Surprisingly, diethyl 2-vinyl-[l,3]-dioxolane-4,5-diacetate 2 is very reactive (Entry 1). Whatever the aryl bromide, complete conversions are observed after 3h and high isolated yields (> 73%) toward the expected compound are achieved. No product issued from the alternative syn-/i-H-elimination is detected. In that case, we suggest that a specific interaction between the ester group and the palladium center could occur leading to a stabilized 7 membered-ring intermediate 7 avoiding thus the formation of undesired product. 

Similarly, the diethyl acetal of acrolein undergoes facile Diels-Alder reactions in the presence of triflic acid, although yields are only moderate. 2-Vinyl-l,3-dioxolane is recommended as the reagent of choice because of higher yields.2... 

Allylnickelhomoenolates,3 2-Vinyl-l,3-dioxolan-4-ones (1), available by condensation of acrolein with (R)- or (S)-2-hydroxyalkanoic acids, react with Ni(COD)2 to form an allylnickel complex which on reaction with ClSi(CH,)3 forms the dark red complex 2. In the presence of light and a polar solvent this complex undergoes... 

Lithium aluminum hydride (LAH) does not, as a rule, react with ethers,but does reduce ortho esters to acetals (equation 2). 2-Vinyl-l,3-dioxolane (5) is reduced to a vinyl ether with double-bond rearrangement (equation 3), but the cinnamyl analog (6) is only reduced at the double bond (equation 4). 

Further monomers with which maleic anhydride produces donor-acceptor complexes are conjugated dienes [191-193], vinyl ethers [194a], furan, thiophene, indole [195, 196], ) -isopropenylnaphthalene [197], 4-vinylpy-ridine [194b], 2-vinyl-l,3-dioxolane [198], cycloalkenes [199] and other complicated vinylic or acrylic monomers [200]. Maleic anhydride complexes have even been observed in some terpolymerizations [201]. 

Catioiuc dienophiles, in which the alkene is rendered electron deficient, are good substrates for the Diels-Alder reaction. 2-Vinyl-l,3-dioxolane 13 is very unreactive towards dienes, however, on protonation, the acetal is in equilibrium... 

The strong protonating property of TfOH is used to generate allyl cations from suitable precursors in low-tenperature ionic Diels-Alder reactions. 3,3-Diethoxypropene and 2-vinyl-l,3-dioxolane add to eyelohexa-1,3-diene in the presence of TfOH to give the corresponding Diels-Alder adducts, the latter in high yield (eq 4). ... 

Coating dispersants 4-Vinyl-5-methyl-m-dioxane, 2-vinyl 5-(chloromethyl)>m-dioxane-5-methyanol, 2-vinyl-l,3-dioxolane-4-methanol Japan 34,148 1970 Asahi Chemical 0 13 Q. x ... 

Casting resins, laminates 2-Vinyl-l,3-dioxane-5-methyl-5-carbinol, 2-vinyl-l,3-dioxane-5-ol, 2-vinyl-l,3-dioxolan-4-carbinol United States 3,433,773 1969 Asahi Chemical... 

Vinyl-l,3-dioxolane, MA reactivity ratios, 300 2-Vinyl-l,3-dioxolane-4-methanol, MA copolymerization, 660 Vinyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionate, MA copolymerization, 276 4-Vinylepoxycyclohexane, MA copolymerization, 340... 

As part of an investigation into new synthetic routes to the important acyclic nucleoside class of antiviral drugs, the cross metathesis of 9-allyl-6-chloropurine with 2,2-dimethyl-4-vinyl-l,3-dioxolane was attempted <2003TL9177>. The reaction was confounded by the coordination of the ruthenium metathesis catalyst with the purine heterocyclic nitrogens. This was overcome to some extent by using the /i-toluenesulfonic acid or hydrogen chloride salts of the... 

A general methodology for the construction of quaternary carbon atoms at the carbonyl carbon of ketones has been successfully exploited for the facile synthesis of ( )-lycoramine (299) (Scheme 30) (165). Thus, the O-allylated o-vanillin 322 was allowed to react with vinyl magnesium bromide followed by Jones oxidation, and the acid-catalyzed addition of benzyl IV-methylcarbamate to the intermediate a,(3-unsaturated ketone furnished 323. Wadsworth-Emmons olefination of 323 with the anion derived from diethyl[(benzylideneami-no)methyl]phosphonate (BAMP) provided the 2-azadiene 324. The subsequent regioselective addition of n-butyllithium to 324 delivered a metalloenamine that suffered alkylation with 2-(2-bromoethyl)-2-methyl-l,3-dioxolane to give, after acid-catalyzed hydrolysis of the imine and ketal moieties, the 8-keto aldehyde 325. Base-catalyzed cycloaldolization and dehydration of 325 then provided the 4,4-disubstituted cyclohexenone 326. The entire sequence of reactions involved in the conversion of 323 to 326 proceeded in very good overall yield and in one pot. 

The absence of attack on the a-carbon of 7 by OH-, in contrast to the reaction in Eqn. 15, would be due to the electron-donation by the /3-carbon of 7. Addition of ethylene glycol vinyl ether to the / -toluenesulfonate salt of [Pt2(NH3)4((CH3)3CC0NH)2(H20)2]4+ in CDC13 catalytically yields 2-methyl-l,3-dioxolane (Eqn. 16). The reaction proceeds almost instantane-... 

The donors used are, for example, 1,3,2-dioxaphospholane [163], 2-phenylimino-l,3-dioxolane [164]. Vinyl monomers with electronegative substituents (acrylic acid, acrylamide, methacrylonitrile, etc.), 3-hydroxy-1-propanesulphonic acid anhydride, / -propiolactone [163], etc. may be used as acceptors. 

Lewis acid-promoted (SnCU or Et2AlCl) rearrangements of allylic acetals provide substituted tetrahydrofurans [80]. Upon addition of SnCU, 4,5-dimethyl-2-phenyl-4-vinyl-l,3-dioxolane rearranges to the all-cw furan (Eq. 48). No racemization is observed with opti-... 

Reactions have been carried out under acidic conditions with malonaldehyde bis(dialkyl acetals).254,31 1 In the examples using methacrylaldehyde, methyl vinyl ketones, or 2-(2-bro-moethyl)-2-methyl-l,3-dioxolane,254 311 apparently a final air oxidation takes place. 

Melhoxy-l-benzopyryltum-.., 503 4,6-Dimelhyl-2-methoxy-pyrylium-.. P03 8-Methyl-7,9-dioxa-bieyelc 4.3.0 nonan-8-en um-.., 504 2-(2,6-Dimethoxy-phenyl)-l,3-dioxoIan-2-enium-.., 505 2-Cyclopropyl-1 J-dioxolan-2-enium-...506 2-Vinyl-1,3-dioxolan-2-enium-.., 506 2-Aryl-l, 3-dioxolan-2-enium-.. . 507... 

Phenyl-vinyl)-l,3-dioxolan-2-eniuiTi-tetrafiuoroborat50 typische Arbeitsvorschrift 2 g (0,01 mol) trans-Zimtsaure-(2-methoxy-ethylcster) und 4 g (0,021 mol) Triethyloxonium-tetrafluoroborat in 10 ml absol. Dichlormethan werden unter Stickstoff 20 Stdn. zum Siedcn erhitzt. Das Gemisch wird auf — 78° gekiihlt, das Salz abgesaugt und mit kaltem Dichlormethan gewaschen. 

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