Allyl alcohol, reactions cyanide

REPPE PROCESS. Any of several processes involving reaction of acetylene (1) with formaldehyde to produce 2-butync-l,4-diol which can be converted to butadiene (2) with formaldehyde under different conditions to produce propargyl alcohol and, form this, allyl alcohol (3) with hydrogen cyanide to yield acrylonitrile (4) with alcohols to give vinyl ethers (5) with amines or phenols to give vinyl derivatives (6) with carbon monoxide and alcohols to give esters of acrylic acid (7) by polymerization to produce cyclooctatetraene and (8) with phenols to make resins. The use of catalysis, pressures up to 30 atm, and special techniques to avoid or contain explosions are important factors in these processes. 

The formation of olefinic nitriles from allylic halides is best accomplished with dry, powdered cuprous cyanide rather than with alcoholic alkali cyanides, with which side reactions such as isomerization and alcoholysis of the double bond are particularly bothersome. With cuprous cyanide the yields in the synthesis of allyl cyanide and methal-lyl cyanide are 84% and 86%, respectively. Higher allylic halides are subject to allylic rearrangements thus cuprous cyanide acts on crotyl halide (CH,CH CHCHjX) and methylvinylcarbinyl halide (CH,CHXCH = CH,) to produce the same mixture of isomeric nitriles (9 1) regardless of which halide is treated. Numerous cyanides of the allylic type (Cj-Ci4) have been prepared, although the possibility of an isomerization has not been considered. A similar isomerization has been observed in the reaction of sorbyl chloride and potassium cyanide. ... 

Tridentate salen ligands (10) derived from 1 have given excellent results in the enantiocontrol of the hetero Diels-Alder addition reaction of dienes with aldehydes (eq 7) and in the asymmetric additions of TMS-azide to mc5o-epoxide and trimethylsilyl cyanide to benzaldehyde (up to 85% ee). Phosphino-oxazolines derived from 1 have been employed for the asymmetric control of palladium-catalyzed allylic substitution reactions products of 70-90% ee were obtained. Photolysis of crystalline adducts of enantiomerically pure 1 with prochiral alcohols results in asymmetric inductions of up to 79% in a rare example of a solid-state enantioselective reaction. ... 

Unfortunately, attempts to perform this substitution reaction on cyclohexenol and geraniol led to the exclusive formation of the corresponding silyl ethers. It thus would seem that one requirement for effective carbon-carbon bond formation is that allylic alcohols be secondary and have possess y,y-disubstitution. Pearson, however, discovered a method with less restriction on the natiue of the substrate he used allylic acetates with y-mono-substitution or primary alcohols [96]. Not only ketene silyl acetals but also a diverse set of nucleophiles including aUyl silane, indoles, MOM vinyl ether, trimethylsilyl azide, trimethylsilyl cyanide, and propargyl silane participate in the substitution of y-aryl allylic alcohol 90 to give allylated 91 (Sch. 45). Further experimental evidence suggests that these reactions proceed via ionization to allylic carboca-tions—alcohols 90 and 92 both afforded the identical product 93. 

Reactions with —OH Groups and Epoxides.—The formation of A -l,2-oxaphos-pholen derivatives from propargylic alcohols and phosphorus trichloride has been studied in detail. Intermediate phosphites (24) and allenic phosphonates (25) are described, and the A -l,2-oxaphosphoIen is produced in the final stage, as shown. Improved conditions have been outlined for the preparation of allylic bromides (26) from allylic alcohols and phosphorus tribromide. Related reactions of primary alcohols with the complex of phosphorus trichloride and DMF lead to the chloride (27) 22 addition of zinc bromide to the reaction results in the formation of alkyl bromides, but an attempt to extend this exchange to the preparation of cyanides was not successful. ... 

Of the five positional isomers of the four-carbon saccharinic acids theoretically possible, 3-hydroxy-2-(hydroxymethyl)propanoic acid (VI) is the only one that lacks an asymmetric carbon atom and is optically inactive and unresolvable. The first attempt at its synthesis, by Glattfeld and cowork-ers, " was by a direct method. The reaction of 2-chloro-2-deoxyglyceritol (LII) [prepared from allyl alcohol (LI) by reaction with hypochlorous acid] with cyanide ion and subsequent hydrolysis of the anticipated nitrile (LIII) should have produced the desired 3-hydroxy-2-(hydroxymethyl)-... 

Regioselective opening of Sharpless epoxides, that is those (enantio-enriched) derived from allylic alcohols, has major synthetic significance. The usual outcome is opening at C-3, but the reaction with nucleophiles such as azide, cyanide and thiophenoxide, in the presence of trialkyl borates, can be highly selective for attack at C-2. ... 

In 1898 Solomina [1] reported that sulfur dioxide reacted with allyl alcohol, allyl methyl ether, and allyl ethyl ether [1]. Solomina reported that carboxyl, halide, and ester groups inhibited the reaction [1]. In 1935 Ryden and Marvel [26] reported that sulfur dioxide did not copolymerize with allyl cyanide or 2-allyl-/i-cresol when peroxide-paraldehyde was used but did polymerize when ascaridole was added [62]. In a later publication Kharasch and Steinfeld reported that allyl chloride copolymerized with sulfur dioxide in the presence of ascaridole and aqueous hydrochloric acid [63]. 

It should be pointed out that manganese dioxide is a mild oxidant that usually converts primary allylic alcohols into conjugated aldehydes without significant further oxidation to carboxylic acids." However, in the presence of HCN and cyanide, the a, -unsaturated aldehydes could be converted into cyanohydrins, which are susceptible to the oxidation of Mn02 to acyl cyanides. In the presence of an alcohol, the a,j8-unsaturated esters are obtained. It should be emphasized that this reaction works only for a,j8-unsaturated aldehydes and will not cause any cis-trans isomerization for the a,/3-unsaturated double bond. For example, benzaldehyde (> 95%), cinnamaldehyde (> 95%), furfural (> 95%), geranial (85-95%), and farnesal (> 95%) have all been transformed into the corresponding methyl esters. ... 

LPDE mediated allylic substitutions have been investigated widely. Substitution reaction of allylic alcohols with silyl ketene acetals, allyl silanes, indoles, methoxymethyl vinyl ether, trimethylsilyl azide, trimethylsilyl cyanide, and propar-gyl silanes proceeds with LPDE (Scheme 3.9) [32, 33]. An experiment with allylic alcohol (5,6) proved that these reaction proceeds via generation of allylic carbocation (Scheme 3.10). Also with a combination of LPDE and AcOH (1 mol%), more efficient allylic substitutions proceed (Scheme 3.11) [34]. 

Mercaptans add to olefins in good yields according to Markovnikoff s rule in the presence of sulfuric acid, boron trifluoride, or sulfur and also in an anti-Markovnikoff fashion in the presence of peroxides or via photochemical means. Vinyl chloride and allyl alcohol give lower yields than conjugated olehnic ketones, aldehydes, esters, and cyanides. Cupric acetate or triethylamine can be used as a catalyst for the reaction of methyl mercaptan with acrolein to give p-mercaptopropionaldehyde in 84% yield. Allene reacts homolytically with methanethiol to give allyl sulfide and the 1,3- and 1,2-dimethyl-thiopropanes. 

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. ... 

If on the other hand the Sn2 reaction with cyanide is favoured, as with allylic 47 or benzylic 50 halides, that method is better.15 Hydrolysis of the nitrile 48 gives the acid 49 but treatment with an alcohol in acidic solution gives the ester 52 directly.16... 

In contrast to allyl halides substituted with one ASG, the cyclopropanation reaction proceeds relatively smoothly when a second ASG is present. Generally, the best results are obtained with sodium borohydride, sodium cyanide, potassium cyanide, and the sodium salts of alcohols or thiols as the nucleophilic species (Table 22, entries 3-26). Even spiroalkanes can be synthesized with the nucleophiles described above (Table 23). Examples illustrating this route are the conversion of a tetracyclic enamino ester with potassium cyanide to the corresponding electrophilic cyclopropane 2, and the facile one-pot synthesis of 1,1 -bis(hydroxymethyl)cyclo-propanes 3 by reduction of halogenated alkylidene malonates with lithium aluminium hydride. ... 

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