2-methyl-l,3-dioxolane

Ethyl-2-methyl-l,3-dioxolane/TsOH, reflux, 75% yield.These con-... 

This study is in excellent agreement with hydrolysis studies of 2-methyl-l, 3-dioxolane (17),... 

Methyl-l,3-dioxolane, production from acetaldehyde, 1 104 (—) -2-M ethyl-1,4-naphthoquinone 2,3-epoxide, 21 242... 

Oligomers from 2-Methyl-l,3-dioxolan, Y. Firat and P.H. Plesch, Journal of Polymer Science, Polymer Letters, 1975,13,135-136. 

Note May contain acetic acid, 2-methyl-l,3-dioxolane, and bis(2-chloroethyl) ether as impurities. May be inhibited with butylated hydroxytoluene. 

For another example of the strong dnality in the chemical behavior of distonic cation-radicals, see Moraes and Eberlin (1998). In the gaseons phase, m- and /7-dehydrobenzoyl cation-radicals ( CgH4C =0) react selectively either as free radicals or as acylium ions, depending on the choice of the reacting partner. Transacetalization with 2-methyl-l,3-dioxolane, ketalization with 2-methoxy-ethanol and epoxide ring expansion with epichlorohydrin demonstrate their acylium reactivity. 

Methyl-4- 2-(2-methyl-l,3-dioxolan-2-yl)ethyl -2-cyClopenten-l-one (7) Typical Procedure13 ... 

Zur Herstellung von 3-(2-Oxo-propyl)-l,2,4-oxadiazolen werden Carbonsau re-ester mit (2-Methyl-l,3-dioxolan-2-yl)-essigsiiure-amid-hydroximid umgesetzt, wobci in einem anschlie-Benden Hydrolyseschritt das cyclische Acetal hydrolysiert wird89-90 ... 

Ethyl 2-methyl-l,3-dioxolane-2-acetate [6413-10-1], 2-methyl-l,3-dioxolane-2-acetic acid ethyl ester... 

All attempts to isolate 2-halogeno-l,3-dioxolanes or -1,3-dioxanes were unsuccessful. For instance, 2-chloro-l,3-dioxolane was detected only by photochlorination of 1,3-dioxolane (Ref. 118) at low temperature and 2-chloro-2-methyl-l,3-dioxolane was prepared by treatment of 2-methyl-l,3-dioxolane-2-carboxylic acid with phosphorus pentachloride at —60°, and shown119 to rearrange to 2-chloroethyl acetate on warming to 0°. For other examples of such problems, see especially, references 120 and 121. 

The photosensitized addition of 1,3-dioxolane and 1,3,5-trioxane to, alkenes was developed a number of years ago as a route to a-alkylated ethers (68JOC805). It has now been shown that 2-methyl-l,3-dioxolane will undergo a photochemically induced conjugate addition reaction to cyclohexenone to afford an adduct (327) in 54% yield which can be hydrolyzed to the diketone (328) (77CJC3986). Functionalized dioxolane (330) was also... 

Treatment of 81 with chlorine afforded a ring-opened product (82) [80CPB1131, 80JAP(K)8D/127372], A ring-opened product (84) was obtained when 9-[3-(2-methyl[l, 3]dioxolan-2-yl)ethyl]-2,3,4,6,7,8-hexahy-dropyrido [2,l-fo][l,3]thiazine (83) was treated with trifluoroacetic acid in boiling THF [94H(37)441]. 

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. 

An improved route to the key intermediate 326 was also developed (165). Namely, 322 was converted to the monoprotected 1,4-dione 327 by sequential addition of the Grignard reagent derived from 2-(2-bromoethyl)-2-methyl-l,3-dioxolane followed by oxidation of the resulting benzylic alcohol with pyridin-ium dichromate (PDC). The ketone 327 was then smoothly transformed to the 2-azadiene 328 by olefination with BAMP. The regioselective addition of n-butyllithium to 328 as before followed by alkylation of the resulting metalloenamine with benzyl A-(2-bromoethyl)-A-methylcarbamate and acid-catalyzed hydrolysis furnished 325, which was converted to the cyclohexenone 326 by base-induced cycloaldolization and dehydration. 

Benzyl-2-methyl-l H-imidazol-4-yl)-5-(2-methyl-[l, 3]dioxolan-2-yl)-pentan-l -one... 

A number of pyrans, including 3-hydroxy-tetrahydropyran (both axial conformer, 29 and equatorial conformer, 30), 2-methoxy-tetrahydropyran 33, 3-methyl-tetrahydropyran 32, and several 4-substituted tetrahydropyrans, along with 2-methyl-l,3-dioxolane and the rigid cyclic ethers 7-oxabicyclo[2.2.1]heptane and 1,8-cineole, were studied extensively by NMR. These empirical results, in conjunction with the literature data for a variety of acyclic and cyclic ethers, were used to examine the reliability of O-substituent chemical shift models in these systems. The empirical data correlate well with predictions made from the model and it is concluded that ethereal oxygen substituent chemical shifts are due to both steric and electrostatic terms <1998J(P2)1751>. 

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