Allylic chlorides, reactions with

The allyl-substituted cyclopentadiene 122 was prepared by the reaction of cyclopentadiene anion with allylic acetates[83], Allyl chloride reacts with carbon nucleophiles without Pd catalyst, but sometimes Pd catalyst accelerates the reaction of allylic chlorides and gives higher selectivity. As an example, allylation of the anion of 6,6-dimethylfulvene 123 with allyl chloride proceeded regioselectively at the methyl group, yielding 124[84]. The uncatalyzed reaction was not selective. 

Alkylation by allylic halides is usually a satisfactory reaction, and in this case the reaction may proceed through a cyclic mechanism.81 For example, when l-14C-allyl chloride reacts with phenyllithium, about three-fourths of the product has the labeled carbon at the terminal methylene group. 

Allyl alcohol can be produced by the hydrolysis of allyl chloride. Together with the main product, allyl alcohol, di-ally ether is produced as a by-product. The conversion of allyl chloride is typically 97 per cent and the yield to alcohol 90 per cent, both on a molar basis. Assuming that there are no other significant side reactions, calculate masses of alcohol and ether produced, per 1000 kg of allyl chloride fed to the reactor. 

An explanation not easily distinguishable from the one involving resonance with a carbonium ion structure in the transition state is that the reactive species is an ion pair in equilibrium with the covalent molecule. This is quite likely in a solvent insufficiently polar to cause dissociation of the ion pairs. Examples of second order nucleophilic displacements accelerated by the sort of structural change that would stabilize a carbonium ion are of fairly frequent occurrence. Allyl chloride reacts with potassium iodide in acetone at 50° seventy-nine times as fast as does -butyl chloride.209 Another example is the reaction of 3,4-epoxy-1 -butene with methoxide ion.210... 

When aqueous NaOH is given as a base, isomerization of the product butenoic acids can be extensive depending on the nature and concentration of base. In dilute aqueous solutions alcohols do not react to form the respective esters, however, the reactions are strongly accelerated due to the increased solubility of the substrates in the catalyst-containing aqueous-alcoholic phase. For example, with 23-33 % (v/v) ethanol in water the [PdCl2(TPPTS)2]-catalyzed hydroxycarbonylation of allyl chloride proceeded with TOF-s of 1850-2400 h and with a vinylacetic/crotonic acid ratio of 21 [16]. Addition of [CuCb] increased the overall conversion rate (by a factor of 2 at [Cu]/[Pd] = 8) but at the same time the side reactions... 

In some cases, 7r-allylpalladium complex formation by retention (syn attack) has been observed. The reaction of the cyclic allylic chloride 33 with Pd(0) affords the 7r-allylpalladium chlorides 34 and 35 by retention or inversion depending on the solvents and Pd species. For example, retention is observed in benzene, THF, or dichloromethane with Pd2(dba)3. However, the complex formation proceeds by inversion in these solvents with Pd(Ph3P)4, whereas in MeCN and DMSO it is always inversion[33]. The syn attack in this case may be due to coordination of Pd to chlorine in 33, because Pd is halophilic. The definite syn attack in complex formation has been observed using stereoche-mically biased substrates. The reaction of the ew-allylic diphenylphosphino-acetate 36 with phenylzinc proceeds smoothly to give 37. The reaction can be explained by complex formation by a syn mechanism[31]. However, these syn attacks are exceptional, and normally anti attack dominates. 

The palladium-catalyzed reaction of aryl- and vinyl-tin reagents with stereochemically defined allyl chlorides proceeds with overall retention of configuration, indicating that the second step, entailing interaction of the iT-allylpalladium complex and the organotin, proceeds by transmetallation and reductive elimination (attack at Pd, retention) (equations 166 and 167).142145 Comparable results were obtained with cyclic vinyl epoxides and aryltins.143... 

The reaction half-time for 4-chloro-2-pentene, the allylic chloride model, with dibutyltin -mercaptopropionate is about 1/20 that for 2-chloro-2-methylbutane, a tert-chloride model, with the same stabilizer. This result supports the choice of an allylic chloride as the most important unstable functionality of poly (vinyl chloride). 

A generalized rate expression for the reaction of allylic chloride (RC1) with metal stabilizers (MX2) includes terms for the unimolecular elimination of HC1 from RC1 and for the bimolecular reaction of RC1 with all metal containing species. 

The nucleophilic photosubstitution reactions of the nitro-substituted allylic bromide 13128 and allylic chloride 14129 with nitronate anion (equations 25 and 26) occur via a photo-induced radical-chain substitution process. Apparently, the allyl radical intermediate in... 

Crosslinked resins of polyethylene imine structure have been prepared by various methods, including the reactions of polyethylene imine with epichlorohydrine 14), with allyl chloride 15), with ethylene dibromide, 6) or dichloride 17), and with toluene diisocyanate l8>. 

The palladium-catalyzed reaction of allyl chloride 11 with the benzyne precursor 104 to produces phenanthrene derivatives 131 is also known [83]. A plausible mechanism for this intermolecular benzyne-benzyne-alkene insertion reaction is shown in Scheme 38. Initially n-allyl palladium chloride la is formed from Pd(0) and 11. Benzyne 106, which is generated from the reaction of CsF and 104, inserted into la to afford the aryl palladium intermediate 132. A second benzyne insertion into 132 produce 133 and subsequent carbopalladation to the alkene afford the cyclized intermediate 134. f>- Iydride elimination from 134 followed by isomerization gave 9-methylphenanthrene 131. 

Strontium enolate chemistry is almost nonexistent barium enolate chemistry is rare radium enolate chemistry is unknown. Allyl chlorides react with barium to form the corresponding organometallics, which in turn react with o ,/ -unsaturated ketones to form the metal enolate . These enolates may also be formed in situ by the reaction of a-chloroketones with barium metal in the presence of an aldehyde, resulting in addition products. These reactions and the enthalpies of formation of the precursor a-haloketones and enones are seemingly ideal candidates for calorimetric investigation. 

Allylic chlorides react with organozinc halides or diorganozincs in the presence of catalytic amounts of CoBr2 [92]. These reactions lead to the 8 2 cross-coupling product with... 

The palladium-catalyzed cross coupling of allyl chloride 6 with vinyltributyltin occurs with net retention of configuration if the reaction is conducted under conditions that favor oxidative syn addition4, though the degree of stereoselectivity is somewhat lower than for its catalytic phenylation using a tin reagent (see Table 27). 

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