Enol sulfonates reaction with acetals

In further modifications of these norprogestins, reaction of norethindrone with acetic anhydride in the presence of p-toluene-sulfonic acid, followed by hydrolysis of the first-formed enol acetate, affords norethindrone acetate (41). This in turn affords, on reaction with excess cyclopentanol in the presence of phosphorus pentoxide, the 3-cyclopentyl enol ether (42) the progestational component of Riglovic . Reduction of norethindrone affords the 3,17-diol. The 33-hydroxy compound is the desired product since reactions at 3 do not show nearly the stereoselectivity of those at 17 by virtue of the relative lack of stereo-directing proximate substituents, the formation of the desired isomer is engendered by use of a bulky reducing agent, lithium aluminum-tri-t-butoxide. Acetylation of the 33,173-diol iffords ethynodiol diacetate, one of the most potent oral proves tins (44). ... 

A study carried out by Kocienski and Lythgoe flrst demonstrated the trans selectivity of the Julia coupling process. The authors found the i uctive elimination could best be carried out with the acet-oxy or benzoyloxy sulfones. If the lithio sulfone derivative is used for addition to the carbonyl, the reaction can be worked up with acetic anhydride or benzoyl chloride to obtain the alkene precursor. In cases where enolization of the carbonyl is a complication, the magnesium derivative can frequently be used successfully. A modification of the reductive elimination was found to be most effective. Methanol, ethyl acetate/methanol or THF/methanol were the solvents of choice and a temperature of -20 C was effective at suppressing the undesired elimination of the acetoxy group to produce the vinyl sulfone. With these modifications of the original procedure, the ability of the reaction to produce dienes as well as rran.r-disubstituted alkenes was demonstrated, llie diastereoisomeric erythro- and threo-acetoxy sulfones could be separated and it was demonstrated that both isomers were converted to the rrans-alkene. It... 

Stable enolates such as diethyl malonate anions react with allyl sulfones (or acetates) in the presence of nickel complexes to give a mixture of the a- and /-product83. The regioselectivity is generally poor in the nickel-catalyzed reaction, but the molybdenum-catalyzed reaction is selective for alkylation at the more substituted allylic site, thereby creating a quaternary carbon center84. 

A recent notable finding in this field is Mukaiyama aldol reactions in aqueous medium (THF H20 = 9 1) catalyzed by metal salts. Lewis acids based on Fe(II), Cu(II), and Zn(II), and those of some main group metals and lanthanides are stable in water. Remarkably, the aldol reaction shown in Sch. 29 occurs more rapidly than the hydrolysis of the silyl enol ether [137]. In the presence of surfactants (dodecyl sulfates or dodecane sulfonate salts), reactions of thioketene silyl acetals with benzaldehyde can be performed in water [138]. 

Thietanone 1,1-dioxide ketals and 3-aminothiete 1,1-dioxides are readily available by cycloaddition of sulfenes to ketene acetals and enamines, respectively (Section V.3.B.). Hydrolysis of these ketals " and the aminothiete sulfones (which are enamines) " " gives 3-thietanone 1,1-dioxides in fair to good yields, as exemplified by the hydrolysis of 133 and 402. Aqueous mineral acids or acidic ion-exchange resins catalyze the reaction. Cis-2-chloro-2,4,4-trimethyl-3-morpholinothietane 1,1-dioxide reacts with N sodium hydroxide to give 38% 2,2,4-trimethyl-3-thietanone 1,1-dioxide, but the trans isomer is recovered unchanged. 3-Methoxy- and 3-ethoxythiete 1,1-dioxide (enol ethers) are also hydrolyzed to 3-thietanone 1,1-dioxide. In several cases, the hydrolysis products are written as enols of the 3-thietanone sulfone. ... 

Inversion of configuration (cf Epimerization) of alcohols (Mitsunobu reaction), 160-161, 286 of ally lie acetates with Pd, 27, 164 of allylpalladium with d-synthons, 27, 264 of alkyl halides or sulfonates by 1,3-dithiane anions, 22 by organylcuprates, 36 by tetracarbonylferrate<2 -X 46-47 in triorganylborane rearr., 37-38 of glycosides with free 2-OH by DAST, 272 of glycosyl halides, 271 of oxiranes by 1-alkync anions, 64, 204 by enolate type anions, 63-64 by internal alcoholate addition, 265 Inversion-esterification of alcohols, 160-161, 286 Inverted DNA , 345-346 Iodide, hydrogen porphyrin synthesis with, 255 Iodine = diiodine (Ij) ... 

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