Phenols amidation

A,<9-Bis(trimethyIsilyl)trifluoroacetamide. The reagent is suitable for the silylation of carfjoxylic acids, alcohols, phenols, amides, and ureas. It has the advantage over bis(trimethylsilyl)acetamide in that the byproducts are more volatile. 

Figure 3. "Phenolic amides" which gel poly (vinyl alcohol)...

Potassium hydroxide. Solid potassium hydroxide is very rapid and efficient. Its use is limited almost entirely to the initial drying of organic bases. Alternatively, sometimes the base is shaken first with a concentrated solution of potassium hydroxide to remove most of the water present. Unsuitable for acids, aldehydes, ketones, phenols, amides and esters. Also used for drying gaseous amines and ammonia. 

The more challenging task of direct C-N bond formation has recently been accomplished by utilization of the oxazoline ring as the nitrogen donor [76 - 78]. This approach was demonstrated by the preparation of spirolactams such as 17 from oxazoline derivatives of tyrosine and related phenolic acids by oxidation with BAIB in trifluoroethanol (Scheme 25), and similar conversions of indole-tethered oxazalones to tetracyclic products through spirolactam intermediates. It is noteworthy that phenolic amides, amines, and iminoethers were not useful for this purpose [78]. 

N, N5,N10,N14-Tetra-p-coumaroylspermidine (phenolic amide) Semi-synthetic - cf. N1,NS,N10-Tri-p-coumaroylspermidine HIV-1 protease (34 pM) [50]... 

The treatment of phenolic amides with BTIB also results in C-O bond formation. Thus, 7V-benzyl-3-(4-hydroxyphenyl)propanamide (135) affords the spirolactone 134 (87JOC3927), while the TV-acytyramines... 

In addition to the abovementioned macromolecular alkyl ketones, it is worth recalling the Mannich reaction on polymers functionalized with phenol, amide, or acetylene moieties - these last give products 434. 

Separation of the Asphaltene. Table I shows the weight percent of the asphaltene fractions and subfractions produced by the separation scheme. The acid fraction, amounting to 81% of the total asphaltene, is the largest fraction isolated by the separation scheme. The primary prerequisite for a compound type to be defined as an acid by the anion, resin appears to be the ability of the compound type to hydrogen bond to the anion resin. Earlier work with distillates and residues identified compound types such as carboxylic acids, phenols, amides, and carbazoles as the major components of an acid fraction (6). Table I shows that Subfraction 3, the subfraction containing the strongest (most readily hydrogen bondable) acids, is more than half of the total acid fraction. 

F6n6ant (638) proposed that a mixture of cyclic and open dimers and higher polymers accounts for the breadth and diffuse character of v. Although there is no question that the band is caused by overlapping absorptions of a variety of species in some cases (e.g., in pure alcohol, phenol, amides), it is also clear that the breadth exists in many systems for which only a single H bonded species is important (e.g., in carboxylic acids, lactams see, for example, 979). Hence proposal (1)... 

Calcium chloride is a very fast and effective drying agent, but may react with alcohols, phenols, amides, and carbonyl-containing compounds. Advantage is sometimes taken of this property to remove not only water from a solvent but, for example, a contaminating alcohol. 

Japanese workers found that magnesium ion strongly accelerates internal cycloaddition in orf/w-phenolic amides perhaps by acting as a coordinating center.52 General discussions of internal cycloaddition are available.53... 

Synthesis of the alkaloids trilobine and obaberine, containing the diphenyl ether linkages, have been accomplished from (5)-(+)-(0)-benzyl-8-bromo-A -benzoylnorarmepavine (80) by Ullmann condensation with the phenolic amide (81) followed by reductive debenzylation to give the phenolic ether (82). ... 

The lactonization step is highly favored because of the steric pressure created by the three methyl groups ( trimethyl lock concept). An alternative to the hydrolytic first step involves a bioreductive generation of the intermediate phenolic amide (Figure 36.23). 

A,0-Bis(trimethylsilyl)trifluoroacetamide. This reagent is suitable for the silylation of carboxylic acids, alcohols, phenols, amides, and ureas. It has the advantage over bis(trimethylsilyl)acetamide in that the by-products are more volatile. It has been used for the selective protection of 10-desacetyI-baccatin III using LHMDS as a catalyst. The TES and TBDMS ethers were prepared similarly. Conventional conditions using the silyl chloride results in silylation of the C-7 hydroxyl ... 

Verkade was able to aminate aryl bromides and chlorides where R1 contains an acidic proton (phenol, amide, or ketone) by simply using 2.4 equiv of LiHMDS rather than the usual 1.4 equiv. NaO/-Bu.46a This procedure works well for cyclic secondary amines and anilines of all types, but gives poor yields for primary aliphatic and secondary acyclic amines. 

R1 = Contains acidic proton (e.g., phenol, amide, ketone, etc.) amine = 2° cyclic no allpahtic acyclic amine = 1 ° anilines no aliphatic... 

A particularly direct synthetic entry to subtarget IV would materialize if a phenolic amide or amine such as Ilia or Illb could be induced to undergo oxidative cyclization to spirodienone IV, which could then be reduced to valuable synthetic intermediates. (Scheme 12). 

The desirability of the transformation of Scheme 12 was recognized as early as 1987, when Kita published a pioneering study of the oxidation of phenolic amides with iodobenzene bis(trifluoroacetate) (PIFA) [23]. However, this intramolecular spirocyclization fails due to the propensity of the nucleophilic oxygen atom of the amide to intercept the electrophilic intermediate arising through activation of the phenol (Scheme 13). The preferential formation of spirolactones is probably due to an electronic effect. In most cases non-nucleophilic solvents are required to prevent solvent participations [24]. 

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