Alcohols, primary secondary

Alcohols can also be reduced indirectly by conversion to a sulfonate and reduction of that compound (10-80). The two reactions can be carried out without isolation of the sulfonate if the alcohol is treated with pyiidine-S03 in THF, and then LiAlH4 added. Another indirect reduction that can be done in one step involves treatment of the alcohol (primary, secondary, orbenzylic) with Nal, Zn, and Me3SiCl. In this case the alcohol is first converted to the iodide, which is reduced. For other indirect reductions of OH, see 10-86. 

Before the synthesis of the pseudoureas was published, Bernthsen and Klinger [6] reported a pseudothiourea synthesis involving the reaction of thioureas with alkyl halides. This reaction was briefly reviewed by Dains [16] and Stieglitz [49, 50], and it found many commercial applications [51-53]. The preparation of isothiouronium salts by the direct action of thiourea and halogen acids on alcohols (primary, secondary, and tertiary) was reported by Stevens [8] and further developed by Johnson and Sprague [54, 55] (Eq. 25). 

Acetylketene (MeC0CH=C=0)—generated by flash photolysis—showed the following selectivities towards functional groups amines > alcohols (primary > secondary > tertiary) aldehydes ketones.19 The results accord with the ah initio calculations, which suggest planar, pseudo-pericyclic transition states. An imidoylketene, PrN=C(Me)CH=C=0, was also generated and showed similar selectivities. 

Interestingly, this strategy was applied to the more reactive propargyl alkoxides allowing for the simultaneously introduction of the three partners at the start of the reaction. In fact, in this case, no side reactions occurred [95]. This process is remarkably versatile, giving good yields of stereodefined 3-arylidene (and alkenyli-dene) tetrahydrofurans 105 with a variety of propargyl alcohols (primary, secondary, and tertiary) and unsaturated halides (aryl iodides, vinyl bromides, and tri-flates) (Scheme 8.45). 

Relative Stability of alcohol, primary, secondary and tertiary models for possible cyclic nitrosamine metabolites as proposed in figure 2. All energies are in kcal/mole. 

Methoxybenzyl ethers. Alcohols (primary, secondary, and tertiary) are derivatized under neutral conditions with the title reagent in the presence of AgOTf in dichloromethane. 

Methoxymethyl ethers. Etherification of alcohols with this reagent is mediated by AgOTf-NaOAc. This method is suitable for derivatizing acid-sensitive alcohols. Primary, secondary, and tertiary alcohols react at comparable rates, phenols slower. 

Bromination of alcohols. Primary, secondary, and tertiary alcohols are converted to bromides. 

Etherification Various alcohols (primary, secondary, tertiary) can be etheri-fied with primary alkyl halides in a reaction mediated by AgOTf and the base 2,6-di-f-butylpyridine. 

Fluorination of alcohols. Primary, secondary, and tertiary alcohols are converted by (1) into the corresponding fluorides the reaction occurs readily at 10° or below. One advantage of this reagent is that products of dehydration and carbonium ion rearrangement are formed in smaller amounts than with SF4, SeF4 pyridine (5, 576-577), and (C2Hs)2NCF2CHClF (5,214-216). It is also useful for fluorination of aldehydes and ketones that are sensitive to acid. 

Alkyt iodides. Alcohols (primary, secondary, and tertiary) can be converted into iodides by reaction with this reagent. The reaction can be carried out on the free alcohol or on the trimethylsilyl ether of the alcohol. Yields of alkyl iodides are usually about the same for both methods. The conversion proceeds with inversion. ... 

Protection of hydroxy groups. Alcohols (primary, secondary, tertiary) can be protected as j3-methoxyethoxymethyl (MEM) ethers. These ethers can be prepared by reaction of (1), slight excess, with either the sodio or lithio derivative of the alcohol in THF or DME at 0° (argon). Alternatively, the ethers can be prepared by the reaction of (1) with alcohols in the presence of ethyldiisopro-pylamine. A third method for etherification is reaction of alcohols with the triethylammonium salt of (1), CH30CH2CH20CH2N (C2H5)3C1, in CH3CN at reflux. Yields by the three methods are >90%. 

Of particular importance is a strong band in the spectrum of aliphatic alcohols usually located near 1060 cm. This absorption has been identified as the C—O stretching mode. The vibrational displacements of this fundamental are similar to the antisymmetric stretch of water (see Chapter 8W for a detailed discussion of the vibrational modes of the water molecule). Since the vibration involves significant displacement of the adjacent C—C oscillator, the vibration wiU be substitution sensitive. These latter shifts can be of value in determining the nature of the alcohol (primary, secondary, or tertiary, see Table 8.9). 

On the other hand, the combined use of ZrCU and Nal can be applied for conversion of hydroxy group into iodide as shown in Equation 81 [86]. In refluxing acetonitrile, methoxybenzyl alcohol was smoothly changed into the corresponding iodide. Benzyl alcohol, primary, secondary, ally lie, and adamantyl alcohols were also converted into the corresponding iodides under the same conditions. 

Silylation of Alcohols. Primary, secondary, and tertiary alcohols are silylated by reaction with TBDMS triflate in excellent yields. For instance, treatment of r-butanol with 1.5 equiv of TBDMS triflate and 2 equiv of 2,6-lutidine in CH2CI2 at 25 °C for 10 min gives a 90% yield of (r-butoxy)-r-butyldimethylsilane. The following alcohols are similarly silylated in excellent yields (70-90%) 2-phenyl-2-propanol, ewufo-norbomeol, c/s-2,2,4,4-tetramethylcyclobutane-l,3-diol, and 9-O-methylmaytansinol (converted to the 3-TBDMS derivative) (eq I). ... 

Arynes combine with all kinds of polar compounds such as lithium halide, alcohols, primary, secondary or tertiary amines, phosphines, and boranes. Of practical, even technical, importance are their reactions with metal hydroxides and alkoxides. The conversion of chlorobenzene by sodium hydroxide at 350 °C into sodium phenolate, an industrial process, obeys the elimination/addition mechanism. Again arynes can be postulated as plausible intermediates. Regardless of which isomer of bromophenol or of bromophenyl benzenesulfonate is heated with sodium hydroxide, resorcinol is always isolated as the main or sole product after neutralization. 

Various types of acyl acceptors, alcohols-primary, secondary, straight and branched-chain, esters can be employed in transesterification using lipases as catalysts. 

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