Acyclic Unsaturated Alcohols

Less important than saturated alcohols, the most common ones are allyl alcohol C3H5OH and oleic alcohol CigH340H. They have no action on aluminium. 

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Typical examples of cyclopropanated acyclic unsaturated alcohols are collected in Table 18. 

Cyclizations of substrates in which internal oxygen nucleophiles have been attached to unsaturated alcohols provide a method for stereoselective formation of acyclic 1,2- and 1,3-diol functionalities, as outlined in Scheme 2. 

Hydroboration of isoprene with catecholborane at 1 1 molar ratio in tetrahydrofliran in the presence of 1 molar % of NiCbCdppe) at room temperature was completed in 6 h. An interesting observation is a lower reactivity of 1-decene compared with isoprene under these conditions. It is the first case of higher reactivity of 1,3-diene than 1-alkene in the hydroboration reaction. It is also an indirect indication that borane is not involved in the reaction, since acyclic conjugated dienes are less reactive than 1-alkenes toward borane. Hydroboration of representative conjugated dienes in the presence of NiCUCdppe) was carried out on a preparative scale and the results are shown in Table 2.9 The mono-hydroboration products were isolated by distillation and oxidized to the corresponding unsaturated alcohols. 

J.2.2 a,p-Unsaturated Aldehydes and Ketones 4J23 Acyclic Allylic Alcohols... 

Monoterpenoids are responsible for fragrances and flavors of many plants and thus their products are used in perfumery and as spices. To date over 1,500 monoterpenoids are known, and these constitute acyclic, monocyclic, and bicyclic monoterpenoids (32), which occur in nature as hydrocarbons, alcohols, aldehydes, and carboxylic acids and their esters. Several acyclic monoterpenoid hydrocarbons are known, and these include trienes such as 3-myrcene (Cl), a-myrcene (C2), (Z)-a-ocimene (C3), ( )-a-ocimene (C4), (Z)-3-ocimene (C5), and ( )-P-ocimene (C6). 3-Myrcene and 3-ocimene are constituents of basil (Oci-mum basilicum, Labiatae) and bay (Pimenta acris, Myrtaceae), pettitgrain (Citrus vulgaris, Rutaceae) leaves, strobiles of hops (Humulus lupulus, Cannabaceae), and several other essential oils. Unsaturated acyclic monoterpene alcohol constituents of plants and their derived aldehydes play a signihcant role in the perfume industry. Some common acyclic monoterpene alcohols and aldehydes include geraniol (C7), linalool (C8) (a... 

A transition metal catalyzed synthesis of ethers by carbene insertion into the O—bond has been reported. Not only saturated but also unsaturated alcohols can be utilized in this catalytic process. ° Intermolecular and intramolecular oxirane ring opening reactions by alkoxides and phenoxides also provide efficient and stereospecific preparations of acyclic and cyclic ethers. The procedures have been surveyed in detail. ... 

For acyclic allylic alcohols, very little a,p-unsaturated enone formation was observed besides epoxidation. Chemoselectivity was much less for cyclic allylic alcohols, for which oxidation of fhe allylic alcohol group competed significantly with epoxidation. In the case of 2-cyclohexenol as the substrate, the enone was even found to be the main product. A comparative sandwich POM-catalyzed epoxidation study of various (subsfifufed) cycloalkenols revealed that the enone versus epoxide chemoselectivity is controlled by the C=C-C-OH dihedral angle Ma in the allylic alcohol substrate. The more this dihedral angle deviates from fhe optimum C=C-C-OW dihedral angle otw for allylic acohol epoxidation, the more enone is formed (Fig. 16.5). 

An investigation of the silver(I) complexes of a series of acyclic, terminally unsaturated alcohols 44) of general formula, CH2 = CH(CH2) OH, where n =... 

Isoprene (2-methylbnta-l,3-diene), a branched diunsaturated Cj hydrocarbon, is the bnilding block of a large family of open-chain and cyclic isoprenoids and terpenoids (Fig. 4.8). Essential oils of higher plants are enriched in monoterpenes (Cj ) with two isoprene nnits. Farnesol, an unsaturated alcohol, is an example of a sesquiterpene with three isoprene units. The acyclic diterpene phytol is probably the most abnndant isoprenoid on Earth. It occnrs esterified to chlorophyll a and some bacteriochlorophylls and is. 

The cyclic sulfates 85 can be reduced easily electrochemically under one-electron transfer conditions to yield a complex product mixture of cyclic ethers, acyclic alkanes, and unsaturated alcohols <1984BCJ3160>. Their alkaline hydrolysis has been studied carefully by ab initio MO calculations <1996J(P2)767> and it was found, in comparison with other cyclic sulfates, to be strongly dependent on the ring size <1997J(P1)3173>. 

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