Pivalamidate

A pivalamide of an indole, introduced with PvCl (NaH, DMF, 0°, 1 h, 96% yield), is efficiently cleaved with MeSNa (MeOH, 20°, 2 h, 96% yield). 

The naphthalene-catalyzed (10%) lithiation of iV-allylic or iV-benzylic pivalamides 66 in the presence of an electrophile at —78 or 0 °C, respectively, gave, after hydrolysis, the expected products 20 (Scheme 25) °. 

An alternative to the use of pivalamides 66 is the lithiation of triflamides 67 catalyzed by naphthalene (4%) in the presence of different electrophiles at temperatures ranging between —78 and 0 °C, so after hydrolysis the expected products 20 were isolated (Scheme 26). ... 

Lithiated tetrahydroisoquinoline pivalamides add to aldehydes with poor diastereoselectivity. However, Seebach and coworkers found that transmetalation to a Grignard... 

The hydrolysis of a hindered amide can often be difficult. V. Bavetsias of the Cancer Research UK Laboratory in Surrey reports (Tetrahedron Lett. 2004, 45, 5643) that mcthanolic Fe(NO,),9H,0 will smoothly hydrolyze pivalamides such as 1 at room temperature. If this proves to be a general procedure for hindered amides, it will be a welcome addition to the armamentarium of organic synthesis. 

Manchanda, V.K., Pathak, P.N., Rao, A.K. 2004. Di(2-ethylhexyl) pivalamide (D2EHPVA) A promising extractant for selective removal of uranium from high level nuclear waste solutions. Solvent Extr. Ion Exch. 22 (3) 353-375. 

A related mechanism is almost certainly observed in the almost instantaneous metha-nolysis of some pivalamide derivatives in the presence of copper(n) chloride. For example, ligand 5.34 forms a five co-ordinate complex with copper(n) chloride. When... 

Non-enolizable amides, for example N,N-dialkyl pivalamides [212], benzamides, thiobenzamides [213], or phosphinamides (Ph2P(0)NR2[214]), can be lithiated a to the amino group by treatment with sBuLi[54, 213, 215] or tBuLi[216], without further additives, in THF at -78 °C. N,N-Dimethylbenzamides can be attacked at the carbonyl group by these organolithium reagents to yield ketones [217] or alcohols, but with sterically more demanding amides metalation is usually faster than addition. 

This rearrangement proceeds via a bicyclic acetal (e.g., 30), and therefore it is a double isomerization involving a ring expansion followed by a ring contraction. It was shown to be most effective using benzamide or pivalamide derivates and the ratio of the ester to the bicyclic acetal was dependent on the reaction conditions used for example, with 5mol% of MeOTf at 130 °C in chlorobenzene, 53% of 29 and 14% of 30 was formed. 

Acyclic C-N bonds of allyl or benzyl triflamides,51 pivalamides and carbamate derivatives9 can be reductively lithiated, as can N-benzyl benzotriazoles.72... 

Figure 4 Molecular structure of O2-bound picket fence iron porphyrin complex. The iron porphyrin has four pivalamide groups forming a hydrophobic cavity for the ligand O2. The axial ligand is 1,2-dimethylimidazole. X-ray crystal structure shows the end-on and bent coordination of O2 to the heme-iron...

Typical geometries observed for anionic complexes relevant to biological systems include the 2-methylimidazolate (2.002 A (Fe-Nax), 0.65 A out of the mean plane of the porphyrin core), phenolate (1.937A, 0.56 A out of plane), thiolate (2.36-2.37 A, 0.4-0.5 A out of plane) and acetate (2.03 A, 0.64 A out of plane) complexes. Note that in cases where the picket fence porphyrin was used, the anionic ligand (imidazolate, thiolate, " and acetate ) is on the same side of the porphyrin plane as the pivalamide pickets . 

The pivalamidate-bridged diplatinum ketonyl complexes may be prepared from the reaction of platinum blue complex and nitric acid in acetone. Two isomers with the amidate configuration in head-to-head and head-to-tail modes and the ketonyl ligand at one axial end are characterized (Scheme 16). An alternative route is from catalyzed oxidation of olefins. ... 

Figure 22-25. Structure of pivalamide derivative of l-(l-naphthyl)ethylamine. (Reprinted from reference 99, with permission.)...

Figure 22-26. Proposed chiral recognition model for the more stable (5, 5 )-complex between (5 )-pivalamide of l-(l-naphthyl)ethylamine and the chiral phase of Figure 22.31. (Reprinted from reference 99, with permission.)...

Photolysis of pivaloyl azide in cyclohexene produces 41% isocyanate, 45% JV-pivaloylaziridine (108), T5% of the allylic amide (109), a trace of bi(cyclohex-2-enyl) (110) and some pivalamide (111). 

Gschwend reported the ortho lithiadon of aniline pivalamides and subsequent addition to nitriles and carbonyls in 1979. A few years later, Wender used a similar aryllithium (H), obtained by metal-halogen exchange, in a new synthesis of indoles (Scheme 7). An analogous metalation occurs when A -phenylimidazol-2-ones are treated with LDA in THF at -78... 

A one-pot procedure for the activation and metalation of tetrahydroisoquinoline involves the carbona-tion of tie li ium amide anion and then further metalation. As is illustrated in Scheme 45, the dipole-stabilized anion species may be added to carbonyl compounds in good yield.For the activation of tetrahydroisoquinoline Grignards, Seebach examined benzamides, pivalamides and phosphoramides, and found that the benzamides would not metalate, and that although the phosphoramides were most easily removed, the pivalamides were the most nucleoj ilic species. As is shown in Scheme 46, the lithiated pi-valoylisoquinoline adds to cyclohexanone in good yield. 

The stereoselective alkylation of tetrahydroisoquinoline pivalamides containing a stereocenter at the 3-position was reported in 1987 by Seebach. The self-immolative chirality transfer process illustrated in Scheme 26 affords only one diastereomer. Oxidative decarboxylation and reduction afford the alkylation products in 5% ee. 

Pivaloyl chloride and base 2 Mixed Some pivalamide may form ... 

Carbon Dioxide, 887 Formamide, 887 W.W -Diethylureide, 887 Dichloroacetamide, 888 Pivalamide, 888... 

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