Acid halides vinylic acylations

The oxidative addition is quite general with alkyl, allyl, benzyl, vinyl, and aryl halides as well as with acyl halides to afford the palladium (II) complex VII. The frans-bis( triphenylphosphine )alkylpalladium halides can also be carbonylated in an insertion reaction to give the corresponding acyl complexes, the stereochemistry of which (17, 18) proceeds with retention of configuration at the carbon bonded to palladium. The acyl complex also can be formed from the addition of the corresponding acid halide to tetrakis (triphenylphosphine) palladium (0). 

Carboxylic acid chlorides and chloroformate esters add to tetrakis(triphenylphosphine)palladium(0) to form acylpalladium derivatives (equation 42).102 On heating, the acylpalladium complexes can lose carbon monoxide (reversibly). Attempts to employ acid halides in vinylic acylations, therefore, often result in obtaining decarbonylated products (see below). However, there are some exceptions. Acylation may occur when the alkenes are highly reactive and/or in cases where the acylpalladium complexes are resistant to decarbonylation and in situations where intramolecular reactions can form five-membered rings. 

Methods of Preparation of Hydrophobically Modified WSPs (HMWSPs). Incorporation of Hydrophobes into WSPs. Water-soluble cellulose derivatives ((hydroxyethyl)cellulose, (hydroxypropyl)cellulose, methylcellulose, etc.) or synthetic polymers containing hydroxyl groups (e.g., poly(vinyl alcohol)) can be reacted with a long-chain alkyl halide (2), acyl halide (2), acid anhydride (6), isocyanate (2), or epoxide (2, 3) under appropriate conditions to form an HMWSP. These reactions are shown in Scheme I. These postmodifications can be done in solution or in hetero-... 

Indoles with carbocyclic halogen or triflate substituents are potential starting materials for vinylation, arylation and acylation via palladium-catalysed pro-cesses[l]. Indolylstannanes. indolylzinc halides and indolylboronic acids are also potential reactants. The principal type of substitution which is excluded from such coupling reactions is alkylation, since saturated alkyl groups tend to give elimination products in Pd-catalysed processes. 

Palladium-mediated addition of silyl stannane reagents to alkynyl ethers has been employed for the synthesis of aliphatic acyl silanes in very good yields via the intermediate a-alkoxy-/J-stannyl vinyl silanes (enol ethers of acyl silanes)82. In a second palladium-catalysed step, the vinyl stannane moiety could be coupled to suitable halides before hydrolysis to the acyl silanes with trifluoroacetic acid (Scheme 11). 

OxazoIones are alkylated at position 4 by alkyl halides, allyl halides and electrophilic alkynes, such as methyl propiolate (equation 36). In contrast, 2-phenyloxazolones react with methyl vinyl ketone at both C(4) and C(2) to yield a mixture of Michael adducts (equation 37). If the phenyl substituent is replaced by the bulky 2,4,6-trimethylphenyl group the addition is directed exclusively to C(4) (81CB2580). Alkylation of 5(4//)-oxazolones is a key step in the synthesis of ketones from a-amino acids (Scheme 16). The outcome of this sequence is the union of the electrophilic fragment R3 with the group R2CO the amino acid thus functions as the equivalent of an acyl anion (78AG(E)450). 

The unsaturated version of the homoenolate synthon, the 3-acyl vinyl anion80 133, can be generated simply in the carboxylic acid series from the halide 134, and has been used in butenolide 135 synthesis81. ... 

The vinyl-copper bond is reactive towards electrophiles such as protic acids (entries 2, 3, 4, 8, 9), Br2,12, alkyl iodides, allyl and benzyl bromide, acyl halides, benzaldehyde, enones (entry 1), propargylic esters (entry 5), and epoxides (entry 10). 

The vinyl-tin bond can be cleaved by electrophiles such as acids, halogens, acyl halides, and metal halides. The cis- and tran.v-styryI stannaries ArCH=CHSnMe3 react with deute-rioacetic acid in MeOD in the presence of aluminium chloride, to give the products... 

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