Pivaloyl chloride

Other Rea.ctlons, The anhydride of neopentanoic acid, neopentanoyl anhydride [1538-75-6] can be made by the reaction of neopentanoic acid with acetic anhydride (25). The reaction of neopentanoic acid with acetone using various catalysts, such as titanium dioxide (26) or 2irconium oxide (27), gives 3,3-dimethyl-2-butanone [75-97-8] commonly referred to as pinacolone. Other routes to pinacolone include the reaction of pivaloyl chloride [3282-30-2] with Grignard reagents (28) and the condensation of neopentanoic acid with acetic acid using a rare-earth oxide catalyst (29). Amides of neopentanoic acid can be prepared direcdy from the acid, from the acid chloride, or from esters, using primary or secondary amines. 

Pivaloyl chloride reacts selectively with the less hindered phenol group. 

Pivaloyl chloride (trimethylacetyl chloride) [3282-30-2] M 120.6, b 57.6"/150mm, 70.5-71/250mm, 104"/754mm, 104-105"/atm, 105-108"/atm, d 1.003, n p 1.4142. First check the IR to see if OH hands are present. If absent, or present in small amounts, then redistil under moderate vac. If present in large amounts then treat with oxalyl chloride or thionyl chloride and reflux for 2-3h, evap and distil residue. Strongly LACHRYMATORY - work in a fumecupboard. Store in sealed ampoules under N2. [Traynham and Battiste J Org Chem 22 1551 1957, Grignard reactns Whitmore et al. J Am Chem Soc 63 647 1941.]... 

Acylation of ami noketone 8 with the acid chloride from p-toluic acid affords the corresponding ester (10) catalytic hydrogenation leads to the bronchodilator bitolerol (11). An analogous scheme starting from the N-methyl ketone (12) and pivaloyl chloride gives ami noalcohol (14). This compound is then resolved to isolate the levorotatory isomer. There is thus obtained the drug dipivefrin. 

Seebach and coworkers have developed the rtmldple coupling reagent, 2-tiitro-2-propenyl 2,2-dimethylpropanoate fNPPi. The reaction of nitromethane v/ith formaldehyde gives 1,3-dihydroxy-2-nitropropane in 95% yield. Subsequent acyladon v/ith two eqidviilents of pivaloyl chloride and elimination of pivalic acid affords NPP. The reacdon may be run on a 40- to 200-g... 

Next, 25.3 g, 0.125 mol, of the above product are dissolved in 250 ml ethyl acetate and 0.125 mol perchloric acid as a 70% aqueous solution is slowly added thereto with continuous stirring. Then, an excess of pivaloyl chloride, 280 ml. Is added and the mixture slowly warmed to reflux temperature. The reaction mixture is refluxed for about 5 hours and allowed to cool to room temperature with continuous stirring. The product is precipitated as the perchlorate salt by the addition of perchloric acid, HCIO4, in 500 ml ether. The product is isolated and purified by dissolving in 75 ml acetone and precipitating it with 150 to 200 ml of water. 

Alternatively, penta-O-acetyl-galactose can be converted to the known 2,3,4,6-tetra-O-acetylgalactopyranosyl azide59 which after treatment with sodium methoxide in methanol and subsequent pivaloylation with pivaloyl chloride in pyridine, also furnishes the O-pivaloylated galactosyl azide60. 

In exceptional circumstances the acylium ion (or the polarised complex) can decompose to give an alkyl cation so that alkylation accompanies acylation. This occurs in the aluminium chloride-catalysed reaction of pivaloyl chloride which gives acylation with reactive aromatics such as anisole, but with less reactive aromatics such as benzene, the acylium ion has time to decompose, viz. 

DMAP (99%) and pivaloyl chloride (99%) were purchased from Aldrich Chemical Company, Inc. and were used as supplied without further purification. 

The reaction was complete at the end of the pivaloyl chloride addition. On 5-L or larger scale, the reaction was conducted at temperatures of 10-15°C without loss of selectivity. 

Water is still introduced from the use of hydrazine hydrate when no additional water is added. Pivaloyl chloride and 1 are both preferentially soluble in the organic phase, which gives rise to 2 as the major product. 

If R is tertiary, RCOmay lose CO to give R, so that the alkylarene ArR is often a side product or even the main product. This kind of cleavage is much more likely with relatively unreactive substrates, where the acylium ion has time to break down. For example, pivaloyl chloride (McaCCOCl) gives the normal acyl product with anisole, but the alkyl product MesCPh with benzene. In the other mechanism an acyl cation is not involved, but the 1 1 complex attacks directly. 

In the most versatile preparation of phosphaalkynes, acid chlorides such as pivaloyl chloride [27] are reacted either with P(SiMe3)3 1692, with formation of TCS 14, or with (Me3Si)2PLi 1725 [26] to give the phosphides 1726 [28, 29], which eliminate hexamethyldisiloxane (HMDSO) 7 in the presence of catalytic amounts of NaOH [28] either in a solvent or more efficiently without a solvent at 120-200 °C [29, 30] to afford, via 1727, the corresponding phosphaalkynes 1728 and HMDSO 7 [1, 4] (Scheme 11.7). 

An alternative approach for the synthesis of 2, 3 -0,0-cyclic //-phosphonate 20a was based on the condensation of a mixture of uridine 3 - and 2 -//-phosphonates (23 and 24 respectively) induced by pivaloyl chloride (Scheme 9) [24], Its reaction with elemental sulfur in carbon disulfide gave 5 -0-DMT-uridine 2, 3 -cyclic phosphorothioate (21a) which after final deprotection afforded the desired 2, 3 -cyclic phosphorothioate 22a (Scheme 9). Its Sp and Rp diastereomers were separated by HPLC [24],... 

Pivalic acid, d679 Pivalic anhydride, d680 Pivaloyl chloride, d681... 

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