2-Acyl-1-methyl

Side-chain lithiation with lithium diisopropylamide and subsequent alkylation or acylation is a practical method for the preparation of various alkyl-, alkenyl- and acyl-methyl-pyridazines 78CPB2428, 78CPB3633, 79CPB916) (Scheme 47). 

The Friedel-Crafts type acylation of 4-methyl-2(3/7)-oxazolone 256 with acyl chlorides in the presence of AICI3 proceeds smoothly to give the 5-acyl -methyl-2(3F/)-oxazolones 257 (Fig. 5.62). ... 

Methyl 5-hexulosonates are the products of oxidation with chromium trioxide of acylated methyl /J-D-hcxopyranosides, which adopt the 4Ci... 

A-Alkylthiabenzenes are deprotonated by LDA and subsequent reaction of the anion with alkyl halides and ketones results in functionalization of the A-methyl group. However, reaction with esters leads to products arising from migration of the acylated methyl group (Scheme 108) <2000MI22>. 

Class 2. Transferases transfer chemical groups from one molecule to another, or within a single molecule. They include amino, acyl, methyl, glucosyl, and phosphoryl transferases, kinases, phosphomutases, transaldolase, and transketolase. 

The structural diversity of metabolites belonging to the different flavonoid classes, including their oxygenation patterns, glycosylation, sulfation, acylation, methylation, and/or prenylation are best illustrated in a recent text,9 as well as in several earlier monographs.10 14 These different substitution reactions, which are catalyzed by substrate-specific and position-oriented enzymes, contribute to the enormous diversity of flavonoid compounds that amount to >5000 chemical structures in Nature and hence, to the wide spectrum of functional roles they play in... 

The shift reagent Eu(facam)3 has also been successfully used to determine the enantiomeric composition of a sample of D,L-3-methyl-3-phenyl-2-pentanone. The chiral shift reagent caused separation of some of the peaks arising from the two enantiomers. The spectrum of D,L-3-methyl-3-phenyl-2-pentanone in the presence of added Eu(facam)3 is shown in Fig. 10.22. The acyl methyl protons are well resolved as seen on the left side of the figure and their relative areas may be integrated. The optical purity of this sample... 

Scheme 1. Acyl methyl selenides require two equivalents of tin hydride for reduction to the corresponding aldehydes...

Acyl radicals are very useful synthetic intermediates. Their preparation is not simple since the corresponding halides are highly electrophilic and cannot be used as radical precursors. Organocobalt compounds were proposed as suitable source of acyl radicals [44]. However, the use of acyl selenides proved to be more general [45, 46]. These radical precursors can be efficiently prepared from the corresponding carboxylic acids and esters [47]. Acyl phenyl selenides should be preferred, when possible, relative to acyl methyl selenides due to the consumption of two equivalents of tin hydride with this last system (Scheme 1) [4]. Acyl selenides have found many applications in tandem radical additions to alkenes. Examples of intermole-cular [Eq. (18)] [48,49] and intramolecular reactions [Eq. (19)] [50a] are reported. The enoyl selenide 68 give the unsaturated acyl radicals 69. This intermediate... 

Heck, R. F. Acylation, methylation, and carboxyalkylation of olefins by Group VIII metal derivatives. J. Am. Chem. Soc. 1968, 90, 5518-5526. 

Curran and Schwarz determined the optimal conditions for a similar acyl radical transfer reaction from acyl methyl selenide to methyl acrylate to achieve the... 

The best example of this approach is provided by carbachol (Fig. 11.20), a long acting cholinergic agent which is resistant to hydrolysis. In carbachol, the acyl methyl group has been replaced by an NH2 group which is of comparable size and can therefore fit the receptor. 

Fig. 6. Survey of the selected fragment ions A-H worked out for the following derivatives trimethylsilylated methyl ester or pertrimethylsilylated derivatives of /V,0-acylneuraminic acids or of A/-acyl-0-alkylneuraminic acids, and trimethylsilylated/methylated /V,/V-acyl,methyl-neuraminic acid methyl ester methyl glycosides [ 15].

A spectrum of isobutyl acetate is shown in Figure 3.48. Note the tall singlet of the acyl methyl group at 2.1 ppm, and the highly deshielded methylene group (3.8 ppm) attached to the oxygen and split into a doublet by its methine neighbor. 

K. Bock, C. Pedersen, and P. Rasmussen, Reactions of acylated pentoses and acylated methyl pentosides with dibromomethyl methyl ether. Preparation of bromo-deoxy-pentoses, J. Chem. Soc., Perkin I, (1973) 1456-1461. 

K. Bock and C. Pedersen, Reaction of acylated methyl arabinosides with hydrogen bromide, Car-bohydr. Res., 29 (1973) 331-338. 

Acylcobalt tetracarbonyls add to conjugated dienes to produce 1-acyl-methyl-rr-allylcobalt tricarbonyls and carbon monoxide (14). 

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