Allyl halides with carbonyls

The reaction of allyl halides with terminal alkynes by use of PdClifFhCNji as a catalyst affords the l-halo-l,4-pentadienes 297. 7r-AlIylpalladium is not an intermediate in this reaction. The reaction proceeds by chloropalladation of the triple bond by PdCh, followed by the insertion of the double bond of the allyl halide to generate 296. The last step is the regeneration by elimination of PdCh, which recycles[148]. The cis addition of allyl chloride to alkynes is supported by formation of the cyclopentenone 299 from the addition product 298 by Ni(CO)4-catalyzed carbonylation[149]. 

Allylation. Homoallylic alcohols are formed by reaction of allylic halides and carbonyl compounds with Al-CoClj. 

Allylation. Tin enolates prefer reaction with allylic halides to carbonyl compounds in the presence of Bu NBr. Thus, the chemoselectivity is reversed by this salt. 

Homoallylic alcohols are formed by combining allyl halides with aldehydes and ketones in the presence of low-valency chromium ions. Aldehydes react faster than ketones enones react very slowly while many other functional groups are inert. The y-carbon atom of the allyl group bonds to the carbonyl carbon atom (Scheme... 

In 1970 Hashimoto published a report on the reaction of potassium hexacy-anodinickelate with organic halides in aqueous solutions [295]. Benzyl bromides were transformed into dibenzyl ketones in the presence of CO in a water-acetone solution. If the reaction was carried out in a water-methanol solution, trans-fi-bromostyrene was transformed into methyl trani-cinnamat. Surprisingly, cinna-maldehyde was also formed in a 10 % yield (Scheme 2.47). The reaction of nickel carbonyl [Ni(CO)4l with organic halides was studied by Bauld in 1963 [296]. Aryl iodides were reacted with Ni(CO)4 in methanol and produced the corresponding methyl benzoate in good yields. If the reaction was carried out in THF, arils were formed. The reaction of allyl halides with Ni(CO)4 in the presence of MgO will produce but-3-enylsuccinic acid [297]. 

A comparison of yields obtained in this study with those obtained in "batch procedures, involving allyl halides, a carbonyl compound and zinc or magnesium is unfavourable to the latter and older) method... 

This was later confirmed when it was shown that reaction of a carbonyl compound with an unidentified species, formed by reaction of the allylic halide with zinc, could be effected in a mixture of THF and saturated aqueous ammonium chloride solution. Sonication was not necessary and the product obtained was the expected homoallylic alcohol. Spontaneous reaction also occurred in water, but at a greatly reduced rate and in these cases reaction was greatly accelerated in the presence of ultrasound. Furthermore, metallic tin could also be used in place of zinc (Schemes 7, 8, and 68). 

Allyl halides with iron monocarbonyl also can produce 7t-allyl-iron halide carbonyls ... 

Mukaiyama, T. Harada, T. Shoda, S. (1980) An efficient method for the preparation of homo allylic alcohol derivatives by the reaction of allyl iodide with carbonyl compounds in the presence of stannous halide, Chem. Lett., 1507-10. 

The preparation of bis (r 3-aiiyi)iron(II) complexes of the type [Fe(ri3-C3H5)2(PMe3)2] has been reported and their reactions with 1,3-dienes to form a mixture of products were described. The reaction of allyl halides with salts of [Fe(CO)3(NO)]- afforded [PeCli -allyl)(CO)2(NO)] complexes, which on treatment with l,2-bis(diphenylphosphino)ethane gave P,Y-unsaturated acyl iron complexes in good yields via regioselective carbonylation with retention of configuration of the allylic double bond. The same [Fe(Ti3-allyl)(CO)2(NO)] complexes were... 

Allylation of perfluoroalkyl halides with allylsilanes is catalyzed by iron or ruthenium carbonyl complexes [77S] (equation 119) Alkenyl-, allyl-, and alkynyl-stannanes react with perfluoroalkyl iodides 111 the presence ot a palladium complex to give alkenes and alkynes bearing perfluoroalkyl groups [139] (equation 120)... 

One of the most gentle methods for the generation of reactive allylmetallic reagents was introduced in 1977 by Hiyama and Nozaki1,2,3,33. By the action of two equivalents of chromi-um(II) chloride on allylic halides in tetrahydrofuran at 0°C in the presence of a carbonyl compound, reductive coupling with the formation of a homoallylic alcohol takes place. 

Palladium complexes also catalyze the carbonylation of halides. Aryl (see 13-13), vinylic, benzylic, and allylic halides (especially iodides) can be converted to carboxylic esters with CO, an alcohol or alkoxide, and a palladium complex. Similar reactivity was reported with vinyl triflates. Use of an amine instead of the alcohol or alkoxide leads to an amide. Reaction with an amine, AJBN, CO, and a tetraalkyltin catalyst also leads to an amide. Similar reaction with an alcohol, under Xe irradiation, leads to the ester. Benzylic and allylic halides were converted to carboxylic acids electrocatalytically, with CO and a cobalt imine complex. Vinylic halides were similarly converted with CO and nickel cyanide, under phase-transfer conditions. ... 

The early synthetic processes using organonickel compounds involved the coupling of allylic halides, which react with nickel carbonyl, Ni(CO)4, to give TT-allyl complexes. These complexes react with a variety of halides to give coupling products.255... 

C-Alkylations of l,4-dihydro-27/-pyrazino[2,l-A]quinazoline-3,6-diones at positions C-l and CM were studied in detail. Compounds of type 57 could be alkylated diastereoselectively at C-l, owing to the geometry of the piperazine ring, which is locked in a flat boat conformation with the R4 or R1 substituent in a pseudoaxial position to avoid steric interaction with the nearly coplanar C(6)-carbonyl group. Alkylation of 57 (R2 = Me, Bn, R4 = Me) in the presence of lithium hexamethyldisilazide (LHMDS) with benzyl and allyl halides resulted, under kinetic control, in the 1,4-trans-diastereomer 59 as the major product, with retention of the stereocenter at CM (Scheme 5). 

The development of the Grignard-type addition to carbonyl compounds mediated by transition metals would be of interest as the compatibility with a variety of functionality would be expected under the reaction conditions employed. One example has been reported on the addition of allyl halides to aldehydes in the presence of cobalt or nickel metal however, yields were low (up to 22%). Benzylic nickel halides prepared in situ by the oxidative addition of benzyl halides to metallic nickel were found to add to benzil and give the corresponding 3-hydroxyketones in high yields(46). The reaction appears to be quite general and will tolerate a wide range of functionality. 

Allylic halides (example 19, Table VII) carbonylate under very mild conditions. An inverse effect of the CO pressure was observed in reaction with Ni(CO)4, CO dissociation being required to allow coordination of the substrate (168). 

NEOPENTYL IODIDE, 51, 44 Nerol, 54, 70 Neryl chloride, 54, 70 Nickel carbonyl, precautions for handling, 52, 117 reaction with allyl halides,... 

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