Sodium pivalate

Reactions with Oxygen Nucleophiles. The hist report of the reaction of oxygen nucleophiles was for the deracemization of cyclic allylic ethers, for example, the palladium(0)-catalyzed reaction of 2-cyclohexeny 1-1 -methyl carbonate with sodium pivalate afforded the pivalate ester in 94% yield and 92% ee. This reaction was extended to other cyclic allylic carbonates. 

While the majority of reports involve the use of carbon- or nitrogen-based nucleophiles, sulfur, oxygen, and even siliconti nucleophiles have also been recorded. In principle, oxygen nucleophiles have the potential to add reversibly to ally lie systems. Complete reversibility of the reaction will afford racemic products, and hence efforts have been made to minimize reversibility (Scheme 38). For example, Trost and Organ have reported the reaction of racemic cyclopentenyl carbonate 179 with sodium pivalate to give enan-tiomerically enriched cyclopentenyl pivalate Careful control of temperature was... 

Recently, Trost and Hembre reported a concise asymmetric synthesis of (+)-cyclophellitol based on the Pd-catalyzed kinetic resolution of racemic conduritol B tetraacetate using the chiral ligand (R,R)A. Most syntheses have started with enantiomerically pure natural products, notably carbohydrates. Such a strategy normally entails rather a long route. A pivalate was chosen as the carboxylate nucleophile for the resolution because the resultant allyl pivalate was anticipated to ionize much more slowly than the starting material. The tetraacetate ( )-conduritol was synthesized from benzo-quinone the kinetic resolution was carried out using 0.65 equiv of sodium pivalate with 1 mol % of (i7 -C3H5PdCl)2 and 3 mol % of (R,R)-AA in a two-phase system with tetra-hexylammonium bromide as the phase transfer catalyst. 

Preparation by heating a suspension of sodium pivalate and 2,6-dipropylphenol in neat triflic acid [6402]. 

Initial attempts to introduce other cyclometalated substituents or bulkier orthosubstituents on the A-aryl group only led to decomposition of the catalyst [48, 73]. Fortunately, replacement of silver pivalate with sodium pivalate allowed for a milder protocol to prepare previously inaccessible catalysts (e.g., 10 and 11) [52, 55]. With the exception of catalysts lacking ort/jo-substitution on the A-aryl ring (e.g., 13) [73], a variety of A-aryl and cyclometalated substituents were accommodated (Fig. 2). When these new catalysts were assayed in homo-CM reactions, a dramatic improvement was noted for catalyst 10, which exhibited TONs approaching 7,400 and near perfect Z-selectivity (>95%) [52]. This represents the highest catalytic efficiency exhibited by a Z-selective olefin metathesis catalyst reported to date. Catalyst 10 maintained remarkable activity and Z-selectivity in a variety of homodimerization reactions, as well as a selection of more complicated RCM and CM reactions (cf. Sect. 3). 

A) PivaloyloxymethylD(—j-Oi-azidobenzylpenicillinate Toa suspension ofpotassiumD(—)-a-azidobenzylpenicillinate (4.14g) and potassium dicarbonate (1.5 g) in acetone (100 ml) and 10% aqueous sodium iodide (2 ml), chloromethyl pivalate (2.7 ml) was added and the mixture refluxed for 2 hours. After cooling, the suspension was filtered and the filtrate evaporated to dryness in vacuo. The remaining residue was washed repeatedly by decantation with petroleum ether to remove unreacted chloromethyl pivalate. The oily residue was taken up in ethyl acetate (100 ml), and the resulting solution washed with aqueous sodium bicarbonate and water, dried and evaporated in vacuo to yield the desired compound as a yellowish gum, which crystallized from ether, melting point 114°C to 115°C. 

The pinacolone may be employed for the preparation of trimethylacetlc acid (pivalic acid) by oxidation with sodium hypobromite solution ... 

Different immobilization methods were applied for Jacobsen s catalyst. The entrapment of the organometallic complex in the supercages of the dealuminated zeolite was achieved without noticeable loss of activity and selectivity. The immobilized catalysts were reusable and did not leach. For the oxidation of (-)-a-pinene the system used only O2 at RT instead of sodium hypochloride at 0 °C. There was a disadvantage in the use of pivalic aldehyde for oxygen transformation via the corresponding peracid. This results in the formation of pivalic acid, which has to be separated from the reaction mixture. 

Adducts [Nb302(02CR)6(THF)3]+ (R = Ph, Bu ) have been prepared by allowing (28) to react with sodium carboxylates (Section 34.5.2.3). [Nb2Cl2(OAc)5(THF)] was obtained with NMe4OAc.621 The reaction between (30) and excess pivalic acid afforded... 

Immediate sodium borohydride (NaBfLt) reduction gave lactam 44. Bischler-Napieralski cyclization of 44 followed by NaBfLt reduction yielded ( )-methyl-0-acetyl-isoreserpate (45). The correct stereochemistry at C-3 was obtained by first lactonizing compound 45 epimerization with pivalic acid then resulted in ( )-reserpic acid lactone (47). Treatment with base followed by acylation with TMBCI yielded racemic reserpine. The stereochemical considerations involved in the epimerization reaction will be discussed later. 

A 57-year old Caucasian man with inflammatory bowel disease was given prednisolone metasulfobenzoate sodium enemas twice daily and oral mesalazine 800 mg tds for about 5 months, without improvement. He stopped using the prednisolone enemas but continued to take mesalazine. Within 48 hours of stopping prednisolone his symptoms resolved completely. The theoretical possibility of contact allergy was entertained. Patch tests with a standard battery of contact allergens, including tixocortol pivalate and budesonide, were ++ positive with budesonide. At follow up 3 months later he was symptom free. 

Mercury(II) pivalate, 319 Mercury(II) trifluoroacetate, 320 Mesembranol, 169 a-Methallyl alcohol, 258 Methanesulfinyl chloride, 248 Methanesulfonic acid, 321 Methanesulfonyl chloride, 322 Methanol-sodium tetraborate, 322 Methoxyamine, 322-323 et Methoxy-a-arylacctic acid esters, 411 p-Methoxybenzyl ethers, 166, 167 Mcthoxycarbonylketene, 340, 341 4(R)-Methoxycarbonyl-l,3-thiazolidine-2-thione, 323-324... 

Troyanov et al. have also reported the synthesis of Ba5(thd)9Cl(H20)7181 and Na2Ba7(thd)2(pivalate)]4(py)4(H20)2181 by reaction of BaCI2 2H20 with the sodium derivative of the ligands. The alkaline-earth metal bromides have been used in the synthesis of M(tdfnd)2 H20 and M(dfhd)2 H20.16° The generalized reaction is shown in Eq. (18). One drawback of these reactions is that they usually yield hydrated compounds. However, it has been shown that tdfnd compounds can be dehydrated by sublimation.161... 

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