Acyl, terminal substituents

Because the anhydride is cyclic, its structural units are not incorporated into a ketone and a carboxylic acid as two separate product molecules. Rather, they become part of a four-carbon unit attached to benzene by a ketone carbonyl. The acyl substituent terminates in a carboxylic acid functional group. 

The ruthenium-catalyzed addition of C-H bonds in aromatic ketones to olefins can be applied to a variety of ketones, for example acetophenones, naphthyl ketones, and heteroaromatic ketones. Representative examples are shown in the Table 1. Terminal olefins such as vinylsilanes, allylsilanes, styrenes, tert-butylethy-lene, and 1-hexene are applicable to this C-H/olefin coupling reaction. Some internal olefins, for example cyclopentene and norbornene are effective in this alkylation. The reaction of 2-acetonaphthone 1 provides the 1-alkylation product 2 selectively. Alkylations of heteroaromatic ketones such as acyl thiophenes 3, acyl furans, and acyl pyrroles proceed with high yields. In the reaction of di- and tri-substitued aromatic ketones such as 4, which have two different ortho positions, C-C bond formation occurs at the less congested ortho position. Interestingly, in the reaction of m-methoxy- and m-fluoroacetophenones C-C bond formation occurs at the congested ortho position (2 -position). 

Dialkyl phosphites such as 49 (Scheme 9) have been reacted as nucleophiles with activated pyridines [69, 70]. The first examples of this chemistry involved either 77-alkyl-pyridinium salts in the presence of DDQ, or pyridine and terminal alkynes as activating agents in a one-step protocol. The reaction proceeds under mild conditions that include AI2O3 catalysis. Quinolines 1 and chloroformates afford the expected adducts 68. The latter structures can be easily oxidized with O3 to provide the substituted indoles 69 (Scheme 12a). Isoquinolinephosphonates obtained this way have been used in Wittig-Homer chemistry. The whole sequence offers ready access to alkyl substituted isoquinolines [71]. Analogously, sUyl substituents have been introduced into A-acylated pyridines by using silylcuprates [72]. 

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