Allylic chlorides, reduction

Even more impoitandy, these lead to reduction by-products in the commercial hydrosdylation reaction with allyl chloride. 

A crystal structure of the C02 derivative of (8), K[Co(salen)( 71-C02)], haso been reported in which the Co—C bond is 1.99 A, the C—O bonds are both equivalent at 1.22 A and the O-C-O angle is 132°.125 Carboxylation of benzylic and allylic chlorides with C02 in THF-HMPA was achieved with (8) electrogenerated by controlled-potential electrolysis,126 in addition to reductive coupling of methyl pyruvate, diethyl ketomalonate and / -tolylcarbodiimide via C—C bond formation. Methyl pyruvate is transformed into diastereomeric tartrates concomitant with oxidation to the divalent Co(salen) and a free-radical mechanism is proposed involving the homolytic cleavage of the Co—C bond. However, reaction with diphenylketene (DPK) suggests an alternative pathway for the reductive coupling of C02-like compounds. 

The electrochemistry of cobalt-salen complexes in the presence of alkyl halides has been studied thoroughly.252,263-266 The reaction mechanism is similar to that for the nickel complexes, with the intermediate formation of an alkylcobalt(III) complex. Co -salen reacts with 1,8-diiodo-octane to afford an alkyl-bridged bis[Co" (salen)] complex.267 Electrosynthetic applications of the cobalt-salen catalyst are homo- and heterocoupling reactions with mixtures of alkylchlorides and bromides,268 conversion of benzal chloride to stilbene with the intermediate formation of l,2-dichloro-l,2-diphenylethane,269 reductive coupling of bromoalkanes with an activated alkenes,270 or carboxylation of benzylic and allylic chlorides by C02.271,272 Efficient electroreduc-tive dimerization of benzyl bromide to bibenzyl is catalyzed by the dicobalt complex (15).273 The proposed mechanism involves an intermediate bis[alkylcobalt(III)] complex. 

Allyl Halides. Reduction of a polyfunctional allyl chloride occurs without rearrangement and without reduction of the tosylate using Ph2SiH2/ZnCl2/... 

Allyl halides, reduction reactions, 31 Aluminum chloride reagent/catalyst alkyl halide reduction, 30-31 secondary alkyl alcohol reduction, 14-15... 

Olefination of the Aldehyde 178 using a stabilized Wittig reagent followed by protecting group chemistry at the lower branch and reduction of the a,p-unsaturated ester afforded the allylic alcohol 179 (Scheme 29). The allylic alcohol 179 was then converted into an allylic chloride and the hydroxyl function at the lower branch was deprotected and subsequently oxidized to provide the corresponding aldehyde 161 [42]. The aldehyde 161 was treated with trimethylsilyl cyanide to afford the cyanohydrin that was transformed into the cyano acetal 180. The decisive intramolecular alkylation was realized by treatment of the cyano acetal 180 with sodium bis(trimethylsi-lyl)amide. Subsequent treatment of the alkylated cyano acetal 182 with acid (to 183) and base afforded the bicyclo[9.3.0]tetradecane 184. 

In the cases of a series of allyl chlorides derived from the antibiotic cephalosporin, reduction leads to a delocalised carbanion, which is protonated on die ester... 

If further acidic C—H bonds in the molecule cause problems, the tin-trick can be applied. The asymmetric deprotonation of a bifunctional carbamate (39a) is accomplished at an early stage and the masked carbanionic centre carried through the synthesis as a stan-nyl group. For instance, the (S)-5-silyloxy-l-tributylstannyl-pentyl carbamate 39b (> 95% ee) was produced by the usual means and converted by standard steps via the aldehyde 78 into the allyl chloride 79 (equation 17) . Lithiodestannylation of 79 by n-BuLi proceeds faster than reductive lithiation in the allylic position to form the lithiocarbamate 80,... 

These can be prepared by a) asymmetric dihydroxylation of allylic chlorides followed by acetonide formation and elimination with BuLi b) catalytic asymmetric transfer hydrogenation and c) reduction of alkynones with chiral metal hydrides, (a) Marshall, J. A. Jiang, H. Tetrahedron Lett. 1998, 39, 1493 Yadav, J. S. Chander, M. C. Rao, C. S. Tetrahedron Lett. 1989, 30, 5455 (b) Matsumura, K. Hashiguchi,... 

The concept of CPTC has been applied in a large number of catalytic reactions such as reduction of allyl chlorides with HCOONa, carbonylation of aryl and allyl halides, allylation of aldehydes, cyanation of aryl halides etc.214 For example, Okano et a/.215 reduced l-chloro-2-nonene to afford 1-nonene and... 

With fumaronitrile and maleic anhydride, IR spectra, after adding olefin and HCN to NiL3, showed only the very stable (olefin)NiL2 complexes. In these cases the oxidative addition of HCN is evidently suppressed by the strongly electron withdrawing character of the olefins. Small amounts of the reduction products were detected by GC/MS after the solutions had stood for a day, however. The failure of allyl chloride to hydrocyanate is no doubt due... 

Primary ally lie amines1 In the presence of this catalyst, allylic chlorides or acetates react with sodium p-toluenesulfonamide in THF/DMSO (80 20) to form the corresponding allylic sulfonamide in 60-85% yield. The products are converted into primary allylic amines on reductive cleavage (sodium naphthalenide). 

There are four processes for industrial production of allyl alcohol. One is alkaline hydrolysis of allyl chloride. A second process has two steps. The first step is oxidation of propylene to acrolein and the second step is reduction of acrolein to allyl alcohol by a hydrogen transfer reaction, using isopropyl alcohol. At present, neither of these two processes is being used industrially. Another process is isomerization of propylene oxide. Until 1984. all allyl alcohol manufacturers were using this process. Since 1985 Showa Denko K.K. has produced allyl alcohol industrially by a new process which they developed- This process, which was developed partly for the purpose of producing epichlorohydrin via allyl alcohol as the intermediate, has the potential to be the main process for production of allyl alcohol. The reaction scheme is as follows ... 

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 addition of sodium phenylsulfinate nucleophiles to stereodefined acyclic allylic chlorides was reported to proceed with complete overall retention of configuration, indicating that this nucleophile adds with inversion of configuration, i.e. via attack at the allyl ligand (equation 193).21S A cyclohexenyl acetate substrate also showed predominant ligand addition, but some isomeric product was also produced (equation 194).216 This loss could be due to acetate epimerization of starting material, ir-allyl epimeriza-tion by PdL2, or by attack of the sulfur at the metal, followed by reductive elimination. 

Replacement of ligands in C3H5MoCl(CO)2(NCMe)2 by isocyanides has given the substituted products C3H5MoC1(CO)2(CNR)2 (R = alkyl) and C3H5MoC1(CO)(CNBu )3, and the reduced products [MoC1(CNBu )4]2 and m-Mo(CO)2(CNR)4 (R = Me, Et). No rationale for the loss of allyl and allyl chloride in the latter two cases was proposed (206). These reactions are rare examples of the formation of low-oxidation state metal-isocyanide complexes via reductive elimination of allyl or allyl chloride from metal-allyl species. The potential applications of mono-, bis-, and tris-n-allylic systems as precursors to low-oxidation state compounds remain to be explored. Substitution and simultaneous reduction of Mo(SBu )4 also occurred on reaction with CNBu to give Mo(SBu )2(CNBu )4 (207) (see Section IV,D,2). 

However, the electrochemical reduction requires a large excess of acids, which produce waste salts during work up and product isolation. This is certainly one of the reasons why the process has so far not competed successfully with the industrial syntheses based on allyl chloride. A few examples of nitrile reduction, which can also be carried... 

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