1.2- Diols from alcohols

We 11 Start by discussing m more detail a class of compounds already familiar to us alcohols Alcohols were introduced m Chapter 4 and have appeared regularly since then With this chapter we extend our knowledge of alcohols particularly with respect to their relationship to carbonyl containing compounds In the course of studying alco hols we shall also look at some relatives Diols are alcohols m which two hydroxyl groups (—OH) are present thiols are compounds that contain an —SH group Phenols, compounds of the type ArOH share many properties m common with alcohols but are sufficiently different from them to warrant separate discussion m Chapter 24... 

To extend the scope of asymmetric transannular C-H insertions, more highly functionalized medium-sized cyclic epoxides have been investigated. A triad of cydooctene oxides 34, 36, and 38, possessing protected diol units, gave the expected alcohols 35, 37, and 39 (Scheme 5.10) [17, 18] an asymmetric synthesis of (-)-xialenon A has been achieved starting from alcohol 39 [19]. In comparison,... 

During the course of this work Tamura et al. (1,14,15) isolated a metabolite from another strain of Helminthosporium sativum. By comparison with the bis-3,5-dinitrobenzoate of the diol from helminthosporal they identified it as the unsaturated aldehyde-saturated alcohol, helminthosporol (VIII, IX). 

The asymmetric oxidation of organic compounds, especially the epoxidation, dihydroxylation, aminohydroxylation, aziridination, and related reactions have been extensively studied and found widespread applications in the asymmetric synthesis of many important compounds. Like many other asymmetric reactions discussed in other chapters of this book, oxidation systems have been developed and extended steadily over the years in order to attain high stereoselectivity. This chapter on oxidation is organized into several key topics. The first section covers the formation of epoxides from allylic alcohols or their derivatives and the corresponding ring-opening reactions of the thus formed 2,3-epoxy alcohols. The second part deals with dihydroxylation reactions, which can provide diols from olefins. The third section delineates the recently discovered aminohydroxylation of olefins. The fourth topic involves the oxidation of unfunc-tionalized olefins. The chapter ends with a discussion of the oxidation of eno-lates and asymmetric aziridination reactions. 

There has in the past been some confusion in the use of the term alkyd, which is said to have been derived from alcohol plus acid. The definition offered by Kienle [1], discussed later, is broad enough to include all polyesters derived essentially from diols and dicarboxylic acids, and consequently linear polyesters were initially included in this class of polymer. On the other hand, Bjorksten et al. [2], in their 1956 compilation of published information about polyesters, restrict the term polyester to the polycondensation products of dicarboxylic acids with dihydroxy alcohols, and say that this definition does not include materials commonly known as alkyds . At the present time, there are still problems of nomenclature in the fibre field arising from the use of polyester as a generic term to cover fibres containing only a very restricted range of chemical groups. 

We, in most cases, have used a 2-meter column of polypropylene glycol (Ucon LB-550 X) on Celite 545 at 191° C. in helium flow and have succeeded in separating the aliphatic alcohols and diols. D. F. Percival s method (18) for separating diols from saponified polyesters should be adaptable to plasticizer analysis. 

Amino-1 J-diols.1 This reagent can be used as an equivalent of NH3 in a synthesis of 2-amino-l,3-diols from chiral 2,3-epoxy alcohols. Thus reaction of the... 

HYDROMAGNESIATION REACTION OF PROPARGYLIC ALCOHOLS (E)-3-PENTYL-2-NONENE-1,4-DIOL FROM 2-OCTYN-1-OL... 

From the kinetics of oxidation of diols by Fc(CN) in aqueous alkali catalysed by R11CI3, it is concluded that oxidation proceeds not by hydride ion transfer from alcohol to Ru(III) but via hydrogen atom transfer, to generate Ru(II) species and an intermediate radical which is further oxidized by more Ru(III).86 Similar conclusions were made from a related study of die oxidation of propan-l-ol under comparable conditions.87... 

A mixed oxide of ruthenium, copper, iron and alumnium has been developed as a catalyst for the synthesis of aldehydes and ketones from alcohols.258 Oxidation of chiral secondary 1,2-diols with 2,3-dichloro-5,6-dicyano-l,4-benzoquinone under ultrasound wave promotion leads to the selective oxidation of benzylic or allylic hydroxyl group. The configuration of the adjacent chiral centre is retained.259 The kinetics of oxidation of ethylbenzene in the presence of acetic anhydride have been studied.260... 

Kishimoto Y, Ogawa I (2004) Amine-catalyzed, one-pot coproduction of dialkyl carbonates and 1, 2-diols from epoxides, alcohols, and carbon dioxide. Ind Eng Chem Res 43(26) 8155-8162... 

For the preparation of diols from olefins see Section 323 (Alcohol - Alcohol). 

A reaction that produces a diol from an alcohol is a ... 

One of the mildest methods for preparing methylene acetals involves reaction of a diol with dimethoxymethane in the presence of a suitable activating agent such as phosphorus pentoxide,176 trimethylsilyl Inflate.177 or lithium bromide and p-toluenesulfonic acid.178 The reaction is also used to make methoxymethyl ethers (see section 4.4,1) from alcohols. Scheme 3,95 illustrates the simultaneous formation of a methoxymethyl ether and a methylene acetal from Shikimic Acid.169 The reaction was adapted to the synthesis of the methylene acetal moiety of the marine antitumour agent Mycalamide B [Scheme 3.96],179... 

From alcohols. Alcohols can be transformed into phenylselenides in a stepwise manner via mesylation and reaction with lithium phenylselenolate. This procedure offers obvious advantages over the formation of the corresponding bromides or iodides when subsequent reaction with strong nucleophiles, such as organolithium compounds, are necessary to prepare the radical precursors. The diol 8 is converted to the bis(phenylselenide) 9 via the corresponding bis(mesylate) as shown in Scheme 2 [6]. Compound 9 is converted to the radical precursor 11 via reaction with lithium phenylacetylide followed by alkylation with allylbromide and a Pauson-Khand reaction. Such a reaction sequence would not be feasible with an alkyl halide. The cyclization afforded the expected tricyclic compound 12 in 95% yield. 

Although hydrosilanes reduce ketones, in trifluoroacetic acid, to the corresponding methylene compounds or dimeric ethers via ionic hydrogenation, the reduction of a-amino and a-oxy ketones and p-keto acid derivatives with hydrosilanes, particularly PhMe2SiH, under these conditions proceeded with high anti selectivity to the alcohols. No racemization was observed at the carbon a to the carbonyl group. Intramolecular hydrosilylation catalyzed by Lewis acids provided a highly stereoselective route to anti-1,3-diols from p-hydroxy ketones (Section 1.1.3. ). ... 

Although diborane (BH3)2 reduces epoxides, it usually gives a mixture of products in addition to the usual alcohols. The reduction of styrene oxide derivatives with diborane has been studied in order to develop a new route to 1,3-diols from epoxides (equation 19).4 a,3-Unsaturated epoxides undergo... 

The reaction may proceed as homo- or cross-dehydrodimerization [105] and takes place with a wide range of substituted substrates such as higher alcohols, ethers, silanes, and partially fluorinated alcohols and ethers, but also with ketones, carboxylic acids, esters, amides, and amines [106]. Besides the formation of 1,2-diols from saturated alcohols, unsaturated substrates are also dimerized under hydrogen to form l,n-diols other than the 1,2-isomers [107]. The regio-selectivity of the diols is controlled by the formation of the most stable radical, which then dimerizes. 

Roush, W. R., Grover, P. T. Diisopropyl tartrate (E)-Y-(dimethylphenylsilyl)allylboronate, a chiral allylic alcohol 3-carbanion equivalent for the enantioselective synthesis of 2-butene-1,4-diols from aldehydes. Tetrahedron Lett. 1990, 31,7567-7570. 

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