For conversion of alcohol into

Heterosubstitutions.—One of the most useful processes for conversion of alcohols into halides (mostly chlorides) is the Appel reaction.247 Treatment of free sucrose with Ph3P and CC14 in pyridine affords tiA -dichloro-b/i -dideoxysucrose in 91% yield.248,249 Surprisingly, a similar procedure performed on a penta-D-benzylsucrose was much less selective.250 Other dihalosucroses (bromides, iodides) are also accessible by reaction with modified Appel or related reagents.251,252... 

For conversion of alcohols into the corresponding bromides, PBr3 is often the reagent of choice and is much more convenient than the alternative of gaseous HBr. The reactions proceed readily at or below room temperature and it should be noted that all three bromines are available for reaction. Typical conditions are illustrated in Protocol 8 for the synthesis of 4-methoxybenzyl bromide 39. 

OH -> /. Verheyden and Moffaii recommend DMF rather than the commonly used benzene as solvent for conversion of alcohols into iodides by this reagent. The reaction in this solvent occurs at room temperature and is usually rapid. Gioleslanol is converted by the reagent in anhydrous DMF in 2 hr. at 25° into 3a-iodochole tane in 57% yield. The reaction of the reagent with alcohols is believed to proceed via... 

Table 10.2 Oxidising agents for conversion of alcohols into aldehydes and...

Similarly applicable for ester syntheses as CDI is A AT -oxalyldiimidazole, which was first described in reference [109]. It has been used to convert not only carboxylic acids but also metal carboxylates into the corresponding imidazolides.[110] Typical reaction conditions for the reactions with oxalyldiimidazole are for the first step 1-2 h, 25-45 °C, and for the second step 4 h, room temperature if X = H if X = Li or Na, if 60 °C and DMF as solvent. In the latter case the resulting Lilm or Naim function as catalysts in the conversion of alcohol into the alcoholate. Results are given in Table 3— 3 [no]... 

A one-pot procedure for the conversion of alcohols into alkylamines is by treatment of the former with hydrazoic acid in the presence of triphenylphosphine and diisopropyl azodicarboxylate addition of triphenylphosphine to the resulting azide gives an hninophosphorane, which is hydrolysed to the alkylamine by water (equation 8)35. 

A convenient one-pot procedure for the conversion of alcohols into primary amines has been reported. The alcohol is converted into the corresponding alkyl halide by the action of bromotrichloromethane/triphenylphosphine and the product is treated successively with sodium azide, triethyl phosphite, hydrochloric acid and sodium hydroxide (equation 20)55, cf. equation 14. 

Tellurium tetrachloride as reagent for the conversion of alcohols into alkyl chlorides and as a Lewis acid catalyst for aromatic alkylation... 

The BTSP-pyridinium dichromate system has proved to be effective for generation of the oxodiperoxochromium complex 22 in dichloromethane. As the peroxo complex decomposed easily, the oxidant BTSP was added dropwise to the reaction mixture using a syringe drive. The BTSP was stable enough even upon contact with the metallic surface of the syringe needle when it was diluted with dichloromethane. Typical results for the conversion of alcohols into carbonyl compounds are summarized in Table 7. 

In contrast to the active site of galactose oxidase, to pre-catalyst 13, and to the system reported by Stack et al., the proposed catalytic species 15 does not imdergo reduction to Cu intermediates, as the oxidation equivalents needed for the catalysis are provided for solely by the phenoxyl radical Hgands. Since the conversion of alcohols into aldehydes is a two-electron oxidation process, only a dinuclear Cu species with two phenoxyl ligands is thought to be active. Furthermore, concentrated H2O2 is formed as byproduct in the reaction instead of H2O, as in the system described by Marko et al. [159]. 

In recent years, dioxiranes have become workhorses for a variety of selective transformations in organic synthesis, from epoxidation of alkenes to the conversion of alcohols into fee corresponding ketones <99CJC308>. Dioxirane-mediated epoxidation continues to be the method of choice for complex substrates wife acid-sensitive functionality. Thus, fee dimethyl-dioxirane (DMD)-mediated epoxidation of the silylated stilbene lactam 159 has been reported as a key step in fee synthesis of protoberberines <99JOC877>. 

Corey and J. E. Anderson154 have described a useful method for the conversion of alcohols into iodides by employing the reagent 120, which is readily prepared from catechol and phosphorus trichloride. Reaction of 120 in ether solution with an alcohol in the presence of pyridine affords the corresponding phosphite 121. Treat-... 

There are no claims that molybdenum(VI) fluoride is of any practical value for the conversion of alcohols into alkyl fluorides. 

There are several methods for the conversion of alcohols into iodides using phosphorus-containing reagents. Two important reagents (Rydon reagents) are methyltriphenoxy-phosphonium iodide 6 and iodotriphenoxyphosphonium iodide 7, respectively formed... 

Many reagents known for the direct conversion of alcohols into halides have been used to achieve site-selective nucleophilic substitution in polyhydroxy compounds [44-46,62]. In some cases, it is possible to effect selective displacements of primary alcohols in the presence of secondary ones, and to achieve differential substitutions of secondary alcohols in unprotected sugars [44,45,64,65] (Scheme 4). 

B. Classon, Z. Liu, and B. Samuelsson, New halogenation reagent systems useful for the mild one-step conversion of alcohols into iodides or bromides, J. Org. Chem. 53 6126 (1988). 

In the meantime, this reaction was modified for the preparative conversion of alcohols into the corresponding iodides304. ... 

Dichloroselenuranes or dibromoselenuranes such as 194 can be used for the conversion of alcohols into the corresponding halides.336 Diphenyldibromoselenurane 195 has been found to be an efficient source for bromine cations (Scheme 57).337... 

Nucleophilic substitution of toluene- -sulphonates (tosy-lates) and other sulphonic esters of secondary steroidal alcohols has received much attention, both in studies of reaction mechanisms, and also as a route for the conversion of alcohols into their epimers. One of the most important practical objectives has been the synthesis of 3a-hydroxy-5a-steroids, which include androsterone and a wide variety of metabolites of the steroid hormones, Tosylates of equatorial 3jS-alcohols (15) give 3a-alcohols or their derivatives (16) in acceptable... 

The trimethylsilyl group was the first to be developed and is widely used for the protection of serine and threonine (Table 6). Chlorotrimethylsilane, l,14 3,3,3-hexamethyldisilazane, and A(0-bis(trimethylsilyl)acetamide are commercially available reagents used for the conversion of alcohols into the corresponding trimethylsilyl derivatives.Furthermore, trimethylsilyl cyanide has been used to protect the side chains of serine, threonine, and ty-rosine.f This silyl protection allows the formation of A -carboxyanhydrides from H-Ser(TMS)-OH and H-Thr(TMS)-OH, and their application in peptide synthesis in the aqueous phase.f l The TMS group can be removed under various conditions, depending on the kind of functional group to which it is bound the TMS ethers are more stable than related amino or carboxy derivatives.These differences in stability allow the direct application of completely silylated hydroxy amino acids in peptide synthesis.b ... 

The combination of triphenylphosphine with esters of trihaloacetic acids provides a reagent system for the stereo- and regio-selective conversion of alcohols into alkyl halides.The bromine-triphenylphosphine adduct has been used at low temperatures (-50 C in dichloromethane) for the removal of the tetrahydropyranyl protecting group from tetrahydropyranyl ethers derived from secondary and tertiary alcohols.The reactions of tertiary phosphines (and other trivalent phosphorus compounds) with iodine in aprotic solvents have received further study, a range of species being identified.The first reported study of the reactions of trivalent phosphorus compounds with monopositive astatine has led to the identification of stable complexes with triphenylphosphine, trioctylphosphine, and triethylphosphite. 

Elemental copper is used as a dehydrogenation catalyst for the conversion of alcohols into aldehydes or ketones [344]. Its efficiency is en-... 

N-Bromobenzopbenoneimine, (C5Hs)2C = NBr (mp 38.5 °C) [747], which is prepared from benzophenoneimine, bromine, and alkalies, is used for the conversion of alcohols into carbonyl compounds [748]. 

Dehydrogenations, which involve the elimination of hydrogen Ifom organic molecules, lead to compounds containing double bonds, multiple bonds, or aromatic rings. For practical reasons, only the formation of carbon-carbon double bonds, of carbon-nitrogen double bonds in cyclic amines, and of aromatic rings (both carbocyclic and heterocyclic) will be discussed in this chapter. The conversion of alcohols into aldehydes and ketones and of amines into imines and nitriles will be discussed in the chapter Oxidations (Chapter 3). 

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