Monoacylated derivatives

B. 2HC1. PtCl. 3HjO, crystallises in yellow leaflets. The base gives a series of esters and also monoacyl derivatives. Hydriodic acid converts it into quitenol, and methyl iodide. 

Acylation of 4 with acid anhydrides in the presence of trifluoromethanesulfonic acid389 gives monoacyl derivatives 9. 6-Acetyltrithiadiazepine 9a undergoes bromination to give 6-acetyl-7-bromo-l,3/.4,5,2,4-trithiadiazepine (10) nitration gives a mixture of the nitro derivative 11 and the dcacctylated compound 5.387... 

An interest in ester migration in the monoacyl derivatives of the vicinal-diol grouping in ribofuranosides stemmed from a desire to establish the position of attachment of the aminoacyl group to the terminal adenosine residue of aminoacyl-(t-RNA),569-571 and also from the necessity of producing suitably protected intermediates for oligoribonucleotide syntheses. That a facile equilibrium can exist is shown by the fact that, on being kept, an ethanol solution of... 

Amino-1,2,4-thiadiazoles yield monoacylated derivatives of type (115) under the usual conditions, whereas 3-amino-1,2,4-thiadiazoles give both monoacyl and diacyl derivatives ((116) and (117), respectively) <84CHEC-I(6)463>. Treatment of 3-amino- and 5-amino-1,2,4-thiadiazoles with sulfonyl halides under basic conditions generally leads to low yields of sulfonamides. By... 

Introducing a second acyl group into monoacyl derivatives of the thiophene series by blocking the ketone group with excess aluminum chloride opened another route to substituted thienothiophene 1. ... 

Glycerol Monoacyl Derivatives were prepd before WWII by IGFarbenindustrie AG, FrP 848740 (1931) CA, 35, 5912(1941), on heating Glycidol Nitrate, QI2.0.CH.CHa(QNO2) with. an org acid... 

Amino-5-methylamino-l,2,4-thiadiazole similarly gives a 3-toluene-p-sulfonamido111,122 (237) and a monobenzamido derivative (for structure, see ref. 122) an excess of the appropriate reagent yields non-acidic di- and tri-substitution products, the latter probably of structure 239. With acetic anhydride, however, acylation terminates with the formation of the 3-monoacyl derivative.111,122 Similar observations areon record concerning 3-amino-5-anilino-1,2,4-thiadiazole86 the only anomalous observation is the ability of this compound to form di- and tri-acetyl derivatives.58... 

All of the examples cited above involve monoacylation of iron-diene complexes. Frank-Neumann has recently demonstrated that monoacylated derivatives are subject to a second acylation and that bis-1,4-diacylated complexes could be obtained in moderate to good yields. Examples ate given in equations (8) and (9) and Table 4.20,23... 

Ketones. Acyclic ketones are named (1) by adding the suffix -one to the name of the hydrocarbon forming the principal chain or (2) by citing the names of the radicals R1 and R2 followed by the word ketone. In addition to the preceding nomenclature, acyclic monoacyl derivatives of cyclic compounds may be named (3) by prefixing the name of the acyl group to the name of the cyclic compound. For example,... 

B). The monoacyl derivatives of N,N-dioctadecyl-l,3-propanediamine are prepared as follows ... 

Dimethyl-188 and 2,6-dimethylpyrazine react very similarly to methylpyrazine. Thus, 2,6-dimethylpyrazine can be converted into a monoanion with sodamide in liquid ammonia which can be condensed with aldehydes and ketones,179 acylated with esters,181 and alkylated with alkyl halides181 to give the corresponding 2-methyl-6-substituted pyrazines. Acylation under suitable conditions also yields diacylated derivatives. Thus, when 2,6-dimethylpyrazine, sodamide, and ethyl benzoate are reacted in 1 3 2 molecular proportion, 38% 2,6-diphen-acylpyrazine (35) and 25% 2-methyl-6-phenacylpyrazine (36) is obtained. From the preparative point of view it is better to form the diacyl derivative by the further acylation of the monoacyl derivative rather than by direct diacylation.187... 

Tagaki, T. and Ando, Y. (1990) Enantiomer separations of mixtures of monoacyl derivatives by HPLC on a chiral column. Lipids, 21, 413. 

Acylation and arylation have not been thoroughly studied. Treatment of the amine (85 R = H) with an acid chloride gives the monoacylated derivative (154). The N-l monoalkylated derivatives of compound (85 R = H) are monoacylated on the exocyclic amino function. Triacylation of... 

Acylation of 3-amino-5-methylamino-l,2,4-thiadiazole (28) with benzoyl chloride (or arenesulfonyl chlorides) introduces one acyl group when one equivalent is employed, and three when a large excess is used to produce (29) and (30), respectively (Scheme 16). With acetic anhydride, however, acylation terminates with the formation of the 3-monoacyl derivative (65AHC(5)ll9). For the mechanism of acylation, see Scheme 3. In the case of 3,5-diarylamino-l,2,4-thiadiazoles, no triacyl derivative is obtained even when excess of acylating agent is employed. Acetyl and benzoyl chlorides give monoacyl derivatives and p-toluenesulfonyl chloride forms 3,5-di(p-toIuenesulfonyl) derivatives (65AHC(5)119). 

By contrast, however, 3,5-diamino-l,2,4-thiadiazoles are selectively converted into amides and sulfonamides in good yields. Thus, acetylation of 3,5-diamino-l,2,4-thiadiazole (53) with excess acetic anhydride yields the symmetrical derivative (133) whereas under similar conditions 3-amino-5-methylamino-l,2,4-thiadiazole and 3,5-diarylamino-l,2,4-thiadiazoles (65AHC(5)119) produce the monoacylated derivatives (134) and (135), respectively. Sulfonylation also results in the preferential formation of the 3-sulfonamides but reaction with excess reagent eventually produces the 3,5-disubstituted derivatives (136) and (137) in good yields (65AHC(5)119). 

Reduction of 101 with lithium aluminum hydride gave the diamine (107) which formed N-methyl and monoacyl derivatives.97... 

The monoacylated derivative (6"-0-butyrate) was detected as the major product by H PLC analysis for all enzymatic reactions, while a diacylated derivative was also detected and confirmed by MS analysis [17]. As it can be seen in Table 9.3, higher regioselectivity of the process was observed in [bmim]BF4 than in [bmim]PF,5, while the selectivity was even lower in acetone. The lower regioselectivity of the enzymatic acylation of polyhydroxylated compounds in [bmim]PF,5 as well as in the organic solvent could be related to the lower solubility of unmodified phenolic substrates in these media, compared to that of their monoacylated derivatives [5, 16, 17]. On the other hand, the enhanced solubility of phenoHc substrates in [bmim]BF4 could explain the increased regioselectivity observed in this ionic liquid. 

The enhanced solubility of all natural polyhydroxylated compounds tested in ionic liquids as compared to traditional organic solvents used for the enzymatic modification of these compounds can be highly useful for the production of great amounts of their acylated derivatives in a single-step biocatalytic process. It is noteworthy that, when the concentration of the above phenoHc substrates was near their solubility limit, the amount of their monoacylated derivatives formed in [bmim]BF4 reached values up to 30.0g/l (in the case of naringin), which were considerably higher than those reported for organic media [10, 30]. 

Lampranthus, it was demonstrated that the pigments are in fact monoacyl derivatives of betanin and isobetanin, respectively, in which an ( )-feruloyl residue is attached to the 6 position (55). Structure 25 for lampranthin II has been unambiguously established by an NMR study (56). 

Occasionally, benzimidazoles are made by cyclization of diacylatcd o-arylencdiamines (38) (Scheme 2.1.17). Ring closure of these compounds requires higher temperahires than for the monoacyl derivatives. They can, however, be cyclized in a melt, or in the presence of acid catalysts, and when conditions are anhydrous, 1-acylbenzimidazoles may be isolated. These latter compounds are azolides , and as such are prone to ready cleavage by nucleophiles. Mixtures of products are likely to be formed if the two acyl groups are different. For example, thermolysis of A/ -acetyl-A/ -benzoyl-o-phenylcnediamine gave a 3 1 mixture of 2-mcthyl- and 2-phenyl benzimidazoles [104]. A recent modification has been used to prepare 1-acetyl-2-mcthylbenzimidazole (39) in quantitative yield [ 105]. Compound (39) can,... 

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