Ketals ethylene oxide

Ethylene dibromide, 126-127 Ethylene dithiotosylate, 540 Ethylene glycol, 69 Ethylene ketals, 322 Ethylene oxide, 41,231-232 Ethylenethioketals, 75,79 Ethyl 3-ethyl-5-methyl-4-isoxazolecarboxyl-ate, 232... 

Ketalization Adipic acid (catalyst). Butanone ethylene ketal. Dimethylformamide ethylene ketal. Ethylene glycol. Mesityl oxide ethylene ketal. p-Toluenesulfonic acid. 

Deprotonation of a-ketal-oo-hydroxy and a-pyridinyl-co-hydroxy poly(ethyl-ene oxide) by Ph2CHK, followed by quenching with (NPCl2)3 results in the formation of the corresponding poly(ethylene oxide) stars based on the... 

A carbonyl group cannot be protected as its ethylene ketal during the Birch reduction of an aromatic phenolic ether if one desires to regenerate the ketone and to retain the 1,4-dihydroaromatic system, since an enol ether is hydrolyzed by acid more rapidly than is an ethylene ketal. 1,4-Dihydro-estrone 3-methyl ether is usually prepared by the Birch reduction of estradiol 3-methyl ether followed by Oppenauer oxidation to reform the C-17 carbonyl function. However, the C-17 carbonyl group may be protected as its diethyl ketal and, following a Birch reduction of the A-ring, this ketal function may be hydrolyzed in preference to the 3-enol ether, provided carefully controlled conditions are employed. Conditions for such a selective hydrolysis are illustrated in Procedure 4. 

The influence of the conformational factors, which play a decisive role in directing oxide fission in the above cases is no longer operative in the case of 3-keto-5a,6a-epoxides and their 3-ethylene ketals. With these substrates the —I effect of the BFs-complexed 3-keto or 3-ketal grouping predominates leading to the fluorohydrins. Thus, treatment of both 5a,6a-oxidopregnane-3,20-dione (35) and its 3,20-bisethylene ketal with BFg-etherate in benzene-ether affords in 45% yield the 6jff-fluoro-5a-hydroxy-derivative (36) and its 3-ethylene ketal, respectively. which are converted into the 6a-fluoro-A -CH3... 

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