3-Aroyl derivatives

Acylation of mesoionic pyrido[l,2-u]pyrimidin-4-ones 150 with aroyl chlorides in the presence of NEts yielded 2-aroyloxy-4//-pyrido[l,2-u]pyrimidin-4-ones 178 (96JHC663). None of the esters 178 could be rearranged to the 2-hydroxy-3-aroyl derivatives 179. The hydroxy group of 9-hydroxy-2-methyl-3- 2-[4-(6-fluoro-l,2-benzisoxazol-3-yl)-l-piperidinyl] ethyl -6,7,8,9-tetrahydro-4//-pyrido[l, 2-u]pyrimidin-4-one was acylated with hexadecanoic acid in CH2CI2 in the presence of dicyclohexylcarbodi-imide and 4-pyrrolidinopyridine at room temperature for 3 days in 80% yield (97MIP7). 

The 2,3-unsubstituted indole 28 undergoes reaction with 4-chloro-N,N-dimethylbenzamide and phosphoryl chloride at 80 °C to give a mixture of the 3-aroyl derivative 40 (50%), 7-aroyl derivative 41 (20%), and yV-aroyl derivative 42 (30%)12 (Scheme 12). 

Under the same conditions, however, triisopropylsilylpyrrole (61) gave 3-acylpyrrole (63) via intermediate (62), and indoles (64ab) also gave the 3-aroyl derivatives (65ab, Scheme 17) (2003JOC5720). 

The enolic form of 2 was confirmed by a ferric chloride color reaction and by its acidity and ultraviolet spectrum, A-Aroyl derivatives of amino acids other than glycine fail to form such azlactones, probably because the stabilization afforded by enolization cannot occur. 

Six-membered heterocycles with one tellurium and two nitrogen atoms in the ring are represented by 2-aroyl derivatives of 1,2,3-telluradiazine and 5,6-benzo-1,2,3-telluradiazine 89. For the synthesis of these compounds, IV-aroylhydrazones of 2-bromotellurenylcyclohexenealdehyde and 2-bromotellurenylbenzaldehyde 90 were used as the starting materials (98ZOK959). Dehydrobromination of the hydrazones 90 occurs on treatment with triethylamine and gives the heterocycles 89 in about 80% yields. 

In C- and N-acyl derivatives of three-membered rings, the geometry of the conformers still seems rather undetermined and, as a result, the same may be said of conformer populations. This is true of simple acetyl derivatives and, of course, of the conformationally more complex aroyl derivatives. For the N-acylaziridines, assignment of nitrogen invertomers seems sufficiently reliable... 

Alkynes are readily acylated with acid chlorides under Friedel-Crafts conditions to form, in most cases, fram-p-chlorovinyl ketones through the corresponding vinyl cation intermediate [Eq. (8.16)]. The first study in 1935 reported low yields.11 Later in acylations with acyl triflates, p-keto vinyl triflates were obtained in satisfactory yields.123 When aroyl derivatives are used, the intermediate can undergo cyclization to form indenones. Chlorovinyl ketones formed from terminal alkynes may also react further losing hydrogen chloride to yield conjugated acetylenic ketones 11,13... 

Pyrazolo[4,3-b]pyridine 181 (R1 = H,R2 = Me) in refluxing pyridine was acylated and tosylated in the 1-position. Milder conditions afforded either a 2-acyl or a mixture of 1- and 2-aroyl derivatives, suggesting a possible equilibrium between the two products.111... 

Benzoxazoles are formed by the action of potassium amide in liquid ammonia on JV-aroyl derivatives of both o- and m-chloroaniline. The reaction does not proceed directly from an intermediate aryne (284), as was once thought, but via isolable o-hydroxyphenylamidines (285 Scheme 29) (81JOC3256). 

Benzothiazoles are formed by the action of sulfur on alkyl- and acyl-anilines. The reaction is realized at elevated temperatures and is accompanied by secondary reactions. In certain cases (aryl and aroyl derivatives) the yields are satisfactory. Thus benzanilide (559) reacts with sulfur affording 2-phenylbenzothiazoIe (560) with a yield of 70%. Benzothiazole is obtained in a similar way (yield 21%) by the action of sulfur on (V,(V-dimethylaniline. 

X-Ray studies show the 2-aroyl derivatives 138 and 139 to favor the A,0-ftr-orientation and the 3-aroyl compounds 140 and 141 to adopt the S,0-trans-fotm (Figure 36). 

Acyl or aroyl derivatives of transition metals are usually prepared by the reaction of an anionic metalate complex with an acyl or an aroyl halide ( 5.8.2.9.1.) ... 

In the attempted tosylation of iV-aroyl derivatives of 2-amino-2-methyl-... 

The product in this case consists of the corresponding acyl or aroyl derivatives. The CO insertion appears to be more rapid than ethylene insertion into the same bond, explaining why the activity of the nickel(II) precursor in the copolymerization reaction increases when carbon monoxide is absent in the initial stages of the process. 

Me5C5Fe(CO)2P(SiMe3)2, a similar product results using mesitoyl chloride, but both benzoyl and pivaloyl chlorides displace both silyl groups to give the bis-acyl (-aroyl) derivatives 76 (Scheme 24)95, a reaction also observed for ruthenium and osmium96. With... 

The first arsaethyne results from the reaction of (Me3Si)2AsLi with 2,4,6-(t-Bu)3C6H2COC1 (ArCOCl). The intermediate aroyl derivative decomposes through loss of siloxane to give the arsaethyne 90 as a pale yellow crystalline solid (equation 84)107. 

Minisci-type radical aroylation of ethyl pyridazine-4-carboxylate gives 5-aroyl derivatives in low to moderate yields, and while these can be saponified yields are low and the free acids are better prepared by direct radical aroylation (Scheme 29). The acids can be decarboxylated to give overall a process for the preparation of 4-aroylpyridazines, though yields are not good <83AP(316)508>. 

Many (benzo)pyridazines are made from 1,4-diketo compounds, and the industrial supply of, for example, maleic and phthalic anhydrides and mucohalic acids make them attractive and widely used starting materials, which can be used in conjunction with substituted hydrazines to give a range of A-substituted derivatives. Some other 1,4-diketo compounds are commercially available on a smaller scale, including, for example, certain 3-benzoylpropionic acids from which 6-aryl-4,5-dihydro-3(2//)-pyridazinones can be prepared. When such precursors are not commercially available then ease and scope of synthetic approaches to the starting materials must be considered, but for established routes, such as 6-aryl-4,5-dihydro-3(2//)-pyridazinones from 3-aroylpropionic acids, a variety of synthetic methods have been developed so that a wide range of (substituted)aroyl derivatives can be prepared. Synthetically useful preformed (benzo)pyridazine derivatives that are commercially available include 4,5-dichloro-3(2F/)-pyridazinone, 3,6-dichloropyridazine, and 1,4-dichlorophthalazine. 

A -Alkylphenoselenazines can be synthesized by adding alkyl halides, or less effectively dialkyl sulfates, to phenoselenazine in liquid ammonia containing sodium amide, and jV-aroyl derivatives are obtained by reactions of the parent heterocycles with aroyl halides <66Mi 624-01 >. jV-Methyl-phenotellurazines are similarly prepared <83JOM(25i)223>. 

Af-Aroyl derivatives of a-aminonicotyrine (99) underwent the Bischler-Napieralski cyclization reaction to give l/f-pyrrolo[3,2-c][l,8]naphthyridine products (38) in excellent yield, the first example of the preparation of pyrrolonaphthyridine compounds being reported in 1960 (Equation (26)) <60JCS1509>. 

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