Allyl alcohol, reactions

Most iridium-catalyzed allylic substitutions have been performed with allylic esters, which are typically synthesized from allylic alcohols. Reactions of allylic alcohols as electrophiles would alleviate the need to prepare the esters from the alcohol. In a few cases, however, iridium catalyzed allylic substitutions have been conducted with allylic alcohols as the electrophile. As discussed earlier in this... 

We have encountered isomer problems with the allylic alcohol reactions, as would be expected, with some reactants. For example, crotyl alcohol and 1-bromo-l-propene with piperidine give a mixture of two isomeric amino alcohols and two enamines (6). 

The reactions of tertiary allylic amines with vinylic halides are related closely to the allylic alcohol reactions since enamines are often major products. We have just begun work in this area and have few results to report yet. We have seen some significant differences in the products formed from tertiary allylic amines and from the related allylic alcohols. A typical example is the reaction of 2-bromopropene with N-allyl piperidine and piperdine where a 42% yield of a single enamine is obtained (6). The related reaction with allyl alcohol gives a mixture of regioisomeric enamines. 

Entry Allylic alcohol Reaction Relative Relative rates at 0 °C ... 

This process occurs for X = O only in two special cases, which have been developed into synthetic methods for alkenes and allylic alcohols. Reaction of BusSnH with 1,2-bis-MDC derivatives gave al-kenes from diols in a process which was independent of the geometry of the starting diol. Examples are the conversions of (84) to (85) and of (86) to (87). 

Titanium acetylides react with 3-benzyl-tetrahydro-l,3-oxazines and 1,3-oxazolidines to give the corresponding / -aminoacetylenes in modest to good yield.296 Vinyl Ti(iv) species prepared by the alkylation of vinylcarbene complexes with BTCl react with aldehydes to give allylic alcohols. Reaction with terminal alkynes produces conjugated dienes, in which a vinyl group regioselectively bonds to the unsubstituted side of carbon-carbon triple bond.297... 

Another ruthenium catalyst was used for the dynamic kinetic resolution of allylic alcohols [reaction (24)] by acylation yielding allylic acetates. Again a redox process should be responsible for the racemization. 

In an extension of the acrolein-allyl alcohol reaction, other alcohols were compared with ethyl alcohol as hydrogen donors. All primary and secondary alcohols which were tried were found to react however, with the secondary alcohols the extent of reaction appears to be governed less by equilibrium considerations than is the case with ethyl alcohol. Thus, the equilibrium constant for the reaction between acrolein and isopropyl alcohol at 396° was estimated from thermodynamic data to be about 350, whereas the experimental product ratio at 400° was 0.03. 

The use of ethyl alcohol for the selective reduction of the carbonyl group in unsaturated aldehydes and ketones other than acrolein is illustrated in Table V. Here also, the data listed are the best obtained in a limited number of runs with each compound and do not necessarily represent optimum conditions. As previously stated, in the acrolein-allyl alcohol reaction a small amount of propyl alcohol is found in the products. This side reaction appears to be considerably more important with crotonaldehyde, since the C4 alcohol fraction here contained 27 % butyl alcohol. The relatively high conversion to saturated alcohol is believed to be due in part to unfavorable reaction conditions. With methacrolein and with methyl isopropenyl ketone the saturated alcohol amounted to 5 % of the imsaturated alcohol produced. 

A feature of the acrolein-allyl alcohol reaction is the small but measurable production of propyl alcohol. This product could arise by rearrangement of allyl alcohol to propionaldehyde followed by hydrogen exchange of propionaldehyde with either ethyl alcohol or allyl alcohol. 

Fluorination of an allylic alcohol. Reaction of methyl gibbeiellate (1) with this fluoroamine in CH2CI2 at 0° gives (2) and (3) as the major products. ... 

A similar transposition can be applied to saturated ketones. For example, a ketone is treated with a vinyl organometallic reagent to generate a derivative of an allylic alcohol. Reaction with benzenesulfenyl chloride then gives an ally lie sulfoxide by means of a (2,31 sigmatropic rearrangement. The remain-... 

Reduction of enones. Sodium borohydride in combination with catalytic amounts of cerium chloride reduces a,/8-unsaturated ketones selectively to allylic alcohols. Reactions proceed within 5 minutes even at 20°. ... 

A mixture of cinnamyl alcohol, phenyl isocyanate, heptanal, tri-n-butylphosphine, and a little Pd(PPh3)4 in acetonitrile refluxed for 5 h - product. Y 82% (E,E E,Z 4 1). The phosphine attacks the less hindered carbon of the intermediate n-allyl complex, and the (E)-geometry of the allyl alcohol is retained for tert. allylic alcohols, reaction requires prior formation of the allyl carbamate ketones react sluggishly. Although stereoselectivity is poor, the method is interesting since intermediate phosphonium salts are formed under neutral conditions. F.e. and polyenes s. N. Okukado et al., Chem. Letters 1988, 1449-52. 

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