Pivalic acid, structure

To complete our survey of structurally-characterized oxide-bridged Mn complexes, we describe species with nuclearities >4. Three distinct types have been reported hexanuclear, nonanuclear and dodecanuclear. The hexanuclear complex Mn602(piv)10(pivH)4 results from the treatment of MnC03 with pivalic acid in reflux-... 

The alkylation products are synthetically useful because simple subsequent transformations furnishes precursors of important natural products as illustrated in Scheme 8E.23. Simple oxidative cleavage of allylic phthalimide 45 generates protected (5)-2-aminopimelic acid, whose dipeptide derivatives have shown antibiotic activity. The esterification via deracemization protocol is not limited to the use of bulky pivalic acid. The alkylation with sterically less hindered propionic acid also occurs with high enantioselectivity to give allylic ester 116, which has been utilized as an intermediate towards the antitumor agent phyllanthocin and the insect sex excitant periplanone. Dihydroxylation of the enantiopure allylic sulfone gives diol 117 with complete diastereoselectivity. Upon further transformation, the structurally versatile y-hydroxy-a,(f-un-saturated sulfone 118 is readily obtained enantiomerically pure. 

The well-known herbicide spike is prepared in high yield by heating in toluene a mixture of pivalic acid, JV-methylthiosemicarbazide, sulfuric acid and polyphosphoric acid to give (228 R = H), which on further treatment with methyl isocyanate yields (228 R = CONHMe) (81USP4283543). Other patented processes are known (76GEP2541115). Details on the structure-activity relationship of compounds in this class are available (70MI42700). A thiadiazole-containing insecticide is methidathion (229). 

What is now known as C-alkaloid A was first isolated by King (14) from S. toxifera bark and named toxiferine IV when it was again isolated from a calabash (16), its identity (15) with King s alkaloid was not known, and the second name has become established. C-Alkaloid A, picrate, mp 228°-229°, [a]D +64° (chloride in water), is formed from toxiferine I under the same conditions that produce C-calebassine from C-dihydrotoxiferine I. These include aerial oxidation in a mixture of pyridine, water, and isobutyric acid (127) or pivalic acid (114) when the acid used is acetic acid, C-alkaloid A is produced along with its 0,0-diacetyl derivative (114) as described earlier in the case of toxiferine I. Most of the properties of C-alkaloid A and its UV-spectrum in neutral, alkaline, and strongly acidic solution are identical with those of C-calebassine. Also, its NMR-spectrum corresponds with that of C-calebassine, with the exception of those signals owing to the hydroxylated side chains. C-Alkaloid A therefore has structure CXXIII (Ri = R2 = OH) C-alkaloid F (see Section III, F) is CXXIII (Ri = H, R2 = OH). 

Figure 33 Structures of (a) pivalic acid (b) 2,2-dimethylbutyric acid and (c) 1 -adamantane carboxylic acid.

Figure 3.6 Structures of (a) [DyL3(H20)3] and (b) [TbL lHiOja] (HL = pivalic acid and HE = 2, 6-dihydoxybenzoic acid) [RE, black O, grey C, white H, omitted]. (Redrawn from the CIF files of M.L. Huang et al, Study on the synthesis and the structures of rare earth complexes with 4-aminobenzoic acid, Huaxue Yanjiu Yu Yingyong (Chinese) (Chemical Research Applications), 18, 245-251, 2006 [30] and T. Glowiak et al., Crystal structure of the isomorphous complexes tetraaquabis(2,6-dihydroxy-benzoato-0)(2,6-dihydroxy-benzoato-0, O)terbium(III) and hohnium(III)dihydrate, Journal of Coordination Chemistry, 48 (4), 477-486, 1999 [43].)...

A pivalate derivative of Tcf, Tc2(02CCMe3)4Cl2, is prepared in low yield from (NH4)3Tc2Cl8 and hot pivalic acid [Tc-Tc 219 pm]" . The structure of Tc2(OC5H4N)4Cl, formed from (NH4)3Tc2Cl8 and 2-hydroxypyridine at 150 C, a Tcf" unit with a Tc-Tc distance of 209.5 pm . 

An exceptional case of an acylphosphonate in which nucleophiles react at the phosphorus rather than at the carbonyl is that of the mixed anhydride of pivalic acid and pivaloylphosphonyl monoester of 5 0-DMT-2 -deoxythymidine (equation 54). In this compound the keto function is especially unreactive, because of steric hindrance, while the phosphorus is unusually electrophilic, being both a mixed anhydride and an acylphos-phonyl function at the same time. As a consequence of these structural features, this compound reacts at the phosphorus with nucleophiles, such as water, ethanol or pyridine, to give products resulting from P—O bond cleavage (equation 54). 

Compound (14) has been prepared by refluxing 1 1 2 mole ratio ofW(CO)6, Cr(CO)6 and pivalic acid in o-dichlorobenzeneIn this structure X = OCH2C(Me)3 and Y = 0, and the average W—separation is 2.610 A. The average oxidation state of the tungsten atoms is -l-Ss or formally W. In this eight electron system, the extra pair of electrons occupies a... 

Figure 3 Structures of [DyL3(H20)3] (a) and [TbL3(H20)4] (b) (HL = pivalic acid and HL = 2,6-dihydroxybenzoic acid) (RE, black O, gray C, white H, omitted). (Reproduced with permission from from R. Wang and Z. Zheng, Rare Earth Complexes with Carboxylic Acids, Polyaminopolycarboxyhc Acids and Amino Acids in Chun-Hui Huang, Rare Earth Coordination Chemistry Fundamentals and Apphcations. John Wiley Sons (Asia) Pte Ltd, 2010.)...

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