Alkenyl tris , preparation

The 2-substituted 3-acylindoles 579 are prepared by carbonylative cycliza-tion of the 2-alkynyltrifluoroacetanilides 576 with aryl halides or alkenyl tri-flates. The reaction can be understood by the aminopalladation of the alkyne with the acylpalladium intermediate as shown by 577 to generate 578, followed by reductive elimination to give 579[425]. 

The mixed triarylphosphine 787 can be prepared by the reaction of (trimethylsily )dipheny phosphine (786) with aryl halides[647]. Ph3P is converted into the alkenylphosphonium salt 788 by the reaction of alkenyl tri-flates[648]. 

Halogen-lithium exchange. Special uses of this method include functionalization of bromoallylamine, preparation of a-silylaldehydes, synthesis of alkenyl tri-flones, trifluoromethyl ketones, alkylidenecyclopentanes" and diaryl tellurides. ... 

Perfluoroallyl fluorosulfate is prepared by the treatment oiperfluoropropene with sulfur tnoxide m the presence of boron catalysts [2, 3, 4, 5, 6, 7] (equation 2) Perfluoroisopropyl allyl ether reacts similarly to give 58% polyfluoroallyl fluorosulfate in a cis/trans ratio of 6 4 [S] Sultones are the exclusive products without catalyst. Polyfluoroolefins such as 2-hydropentafluoropropylene [9], (2,3-dichloropropyl)tri-fluoroethylene [70], perfluoropropene [2, i], perfluoroisopropyl alkenyl ethers [S], and acyclic polyfluoroallyl ethers [77] undergo sulfur trioxidation to regioselectively produce the corresponding P-sultones in high yield... 

The results published thereafter by Kochi s group are especially interesting from a mechanistic point of view . Indeed, for preparative chemistry the yields are not satisfactory and the reaction is limited to reactive alkenyl bromides such as propenyl and styryl bromides (Table 4). Neumann and Kochi were the first to replace iron(III) chloride by iron(III) acetylacetonate or related complexes such as Fe(dbm)3 (iron tris-dibenzoylmethanato) that are less hygroscopic and easier to handle. 

A wide variety of RCCo3(CO)9 complexes may be prepared (R = H, halogen, alkyl, aryl, alkenyl, acyl, alkoxycarbonyl, aminocarbonyl, triorganosilyl, dialkyl phosphino, alkoxy, dialkylamino, etc.), either by direct reactions of octa-carbonyl dicobalt with organic tri- and dihalides or by acid-induced reactions of... 

In addition to the head-to-head cross-coupling reactions, it has been discovered that the reaction of phenyl or 1-alkenyl iodides with (E)-l-alkenyl-l,3,2-benzo-dioxaboroles produces the head-to-tail cross-coupling products, 2-phenyl-1-alkenes or 2-alkyl-1,3-alkadienes, respectively (Eq. 107) The reaction is profoundly affected by catalytic quantities of palladium compounds (Pd black prepared by reduction of Pd(OAc)j with diborane is especially effective) in the presence of tri-ethylamine. 

Low-valent nickel species catalyze the reaction between Grignard reagents and aryl or alkenyl sulfide in the preparation of alkylarenes, biaryls, and alkenes (see citations in Ref. ///). Wenkert et al. recently isolated compounds 132 and 133 to show that an oxidative addition occurs between diaryl sulfides and tris(tri-/ -butyl)phosphinonickel (77/). 

The authors found that branched alkyl phosphines were not useful at all, whereas aryl phosphines afforded 1145 in acceptable yield but modest trans/cis selectivity (Scheme 1.298). However, both triethylphosphine and tri- -butylphosphine produced 1145 in nearly quantitative yield with 100 0 trans/cis selectivity. Operationally, the phosphonium salts were generated in situ, triethylphosphine was the reagent of choice. Similarly, the tranr-2-alkenyl bis- and ttis-oxazoles 1147—1150 were readily prepared. A further application of this methodology for the synthesis of ulapuahde A is discussed in Section 1.5.6. 

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