Acetoxymethylation

The reaction can be applied to allyl malonates. Alkylation of diallyl mal-onate (734) with bromoacetate and acetoxymethylation afford the mixed triester 735. Treatment of the tricster 735 with Pd catalyst affords allyl ethyl itaconate (736). In a similar way, a-methylene lactone and the lactam 737 can be prepared[462]. 

Only one reaction of thiazole N-oxides has been studied in detail. The rearrangement in acetic anhydride of 2,4-dimethylthiazoIe-3-oxide gave 2-acetoxy-4-methylthiazole and 4-acetoxymethyl-2-methylthiazole in a ratio of about 4.5 to 1(264). 

The Prins reaction with formaldehyde, acetic acid, acetic anhydride, and camphene gives the useful alcohol, 8-acetoxymethyl camphene, which has a patchouli-like odor (83). Oxidation of the alcohol to the corresponding aldehyde also gives a useful iatermediate compound, which is used to synthesize the sandalwood compound dihydo- P-santalol. 

Longifolene. There are at least four commercially important aroma chemicals made from (+)-1ongifo1ene and about thirteen products made from (-)-isolongifolene (90) (182). Acetoxymethyl longifolene or the formate are formed during the Prins reaction on (+)-1ongifo1ene. Saponification of the esters gives the useful perfumery alcohol (183) (Fig. 9). 

AH cephalosporins found in nature (Tables 1 and 2) have the D-a-aminoadipic acid 7-acyl side chain (21). AH of these compounds can be classified as having rather low specific activity. A substantial amount of the early work in the cephalosporin area was unsuccessfiiHy directed toward replacing the aminoadipic acid side chain or modifying it appropriately by fermentation or enzymatic processes (6,22). A milestone ia the development of cephalosporins occurred in 1960 with the discovery of a practical chemical process to remove the side chain to afford 7-ACA (1) (1). Several related processes were subsequendy developed (22,23). The ready avaHabHity of 7-ACA opened the way to thousands of new semisynthetic cephalosporins. The cephalosporin stmcture offers more opportunities for chemical modification than does that of penicillins There are two side chains that especiaHy lend themselves to chemical manipulation the 7-acylamino and 3-acetoxymethyl substituents. 

For a viable commercial process, the selection of materials and the choice of synthetic route is governed primarily by cost, not by overall yield. The selection of starting material is dictated usually by the desked C-3 substituent. For cephalosporins containing 3-acetoxymethyl or 3-(substituted)methyl such as 3-thiomethyl and 3-aminomethyl derived moieties, the most dkect synthetic route is from cephalosporin C, whereas pencillin V or G is the preferred starting material for the synthesis of the C-3 methyl cephalosporins. The three chemical transformations (2), (5), and 6) can potentially be carried out in a variety of ways, the precise sequence being determined by a balance of competing factors such as cost and optimization of yield (87). 

Cyanuric acid readily dissolves in aqueous formaldehyde forming tris(hydroxymethyl)isocyanurate [10471-40-6] (THMIC) which can be isolated by evaporation (11). THMIC in turn reacts with acetic anhydride to yield tris(acetoxymethyl)isocyanurate [54635-07-3], either thionyl chloride or phosphoms pentachloride to give tris(chloromethyl)isocyanurate [63579-00-0], and phenyl isocyanate in pyridine to yield tris(A/-phenylcarbamoxymethyl) isocyanurate [21253-39-4] in 87% yield (65). Reaction of CA with paraformaldehyde and 2,6-dicyclohexylphenol yields... 

Chloro-4-methyl- and 6-methoxy-4-methyl-pyridazine 1-oxides give the corresponding 4-acetoxymethyl derivatives, while the corresponding 6-substituted 5-methylpyridazine 1-oxides do not react at the methyl group. 

For the reactions of methylpyridazine 1-oxides with benzaldehyde in the presence of sodium methoxide, the order of reactivity of methyl groups at various positions is 5 > 4,6 > 3. 3-Methylpyridazine 1-oxide is converted by acetic anhydride into the 3-acetoxymethyl compound, which is easily hydrolyzed to 3-hydroxymethylpyridazine. 

Pteridine, 2,4-bisacetamido-6-acetoxymethyl-hydrolysis, 3, 295 Pteridine, 2,4-bis(methylthio)-synthesis, 3, 299... 

Thiazole, 4-acetoxymethyl-2-methyl-synthesis, 6, 254 Thiazole, 2-acetyl-occurrence, 6, 327... 

Hydroxy-4-oxa-5a-acetoxymethyl-androstan-3-one acetate, 305 17 -Hydroxy-4, 5/8 Oxidoandrostan-3-one, 20 3 -Hydroxy-16a, 17 a-oxidopregn-5-en-20-one, 196... 

Me3SiCl, AC2O, 90%. Treatment of the resulting acetoxymethyl ether with acid or base readily affords the free alcohol. 

A/-o-(Benzoyloxymethyl)benzoyl, 562 A/-(2-Acetoxymethyl)benzoyl, 562 A/-2-[(t-Butyldiphenylsiloxy)methyl]benzoyl, 562 A/-3-(3, 6 -Dioxo-2, 4, 5 -trimethylcyclohexa-1, 4 -diene)-3,3-dimethylpropionyl, 562 AZ-o-Hydroxy-frans-cinnamoyl, 562... 

Chemical Name Sodium 3-acetoxymethyl-7-[2-(2-amino-4-thiazolyl)-2-methoxyimino]-acetamido-3[Pg.267]

A solution of B g of sodium bicarbonate in about 20 ml of ethanol was progressively added to 45.55 g of pure 3-acetoxymethyl-7-[2-(2-amino-4-thiazolyl)-2-methoxyiminoacetamido)arboxylic acid in 100 ml of distilled water and another BO ml of ethanol and 4.5 g of activated carbon were added thereto. The mixture was stirred for 5 minutes and was filtered. The filter was rinsed with ethanol and the filtrate was evaporated to dryness under... 

The synthesis is straightforward because for the preparation of the tetrapyrranc a bipyrrole can also be used as a central unit to which a benzyl 5-(acetoxymethyl)pyrrole-2-carboxylate can be attached as the terminal pyrrole rings. Debenzylation by catalytic hydrogenation then gives the desired tetrapyrrane building block 68. 

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