Alcohols, Preparation Tertiary

A method that allows for alcohol preparation with formation of new carbon-carbon bonds Primary sec ondary and tertiary alcohols can all be prepared... 

Batch or continuous processes can be used to prepare tertiary amines from alcohols and ammonia or a secondary amine, such as, dimethylamine. 

Yields of chlorides are good to excellent for primary and secondary alcohols, but a competing olefin-forming elimination process renders the method of limited value for preparing tertiary chlorides.12 An adaptation of the procedure using carbon tetrabromide allows the synthesis of alkyl bromides. Some examples are the preparation of rt-C5H11Br (97%) and C H6CH2Br (96%).12 Farncsyl bromide has been prepared in 90% yield from fame sol.23... 

When solutions of alcohols in fluorosulphonic acid or fluorosulphonic acid-sulphur dioxide were prepared, tertiary carbonium ions could be generally observed, but peak broadening (due to exchange) and side products are observed. Secondary and primary alcohols form generally only the monosulphates. 

Reaction between quinuclidin-3-one (2) and organolithium or organomagnesium compounds is a general method for preparing tertiary alcohols.47,162,164-168 By dehydration of these alcohols substances with a semicyclic double bond (127) are formed together with A 2-dehydroquinuclidine derivatives (126).165-168 Reduction of unsaturated compounds gave various 3-substituted quinuclidines (128). 

The metal lias to a great extent replaced zinc, which was used in 1849 by Frankland in the preparation of paraffin hydrocarbons and the zinc alkyls, and subsequently by Wagner for preparing secondary alcohol from aldehydes, by Saytzeff in preparing tertiary alcohols from ketones, and by Butlerow iu the preparation of both ketones and tertiary alcohols from acid chlorides. 

Feshchenko and Kirsanov more recently have reported the reaction of red phosphorus with iodine and an alcohol to prepare tertiary phosphines in 85-90% yield (13). 

Amidinium salts (obtainable by various methods, compare Section 2.1.2.5) which are not peralkylated at nitrogen are converted to amidines by treatment with strong bases, e.g. aqueous alkali metal hydroxides, alcoholic alkoxides, tertiary amines etc. As already mentioned it is not difficult to alkylate amidines (see Section 2.7.2.5.4), thus by subsequent alkylation and deprotonation reactions amidines can be synthesized carrying the desired substituents at nitrogen, e.g. (308 Scheme 47). A series of trisubstituted formamidines have been prepared by reaction of anilines with the azavinylogous form-amidinium salt (309). ... 

Preparation of carbamates. Carbamates of alcohols, even tertiary (which are easily dehydrated), can be obtained in good yield by stirring the alcohol with 2 equivalents each of sodium cyanate and trifluoroacetic acid in benzene or methylene chloride at room temperature for a few hours (Loev and Kormendy ). A mildly CH, CH, o... 

SOLUTION TO 8a A tertiary alcohol is obtained from the reaction of an ester with two equivalents of a Grignard reagent. Therefore, tertiary alcohols prepared in this way must have two identical substituents on the carbon to which the OH is bonded, because two... 

A general synthesis for all diastereomeric L-hexoses, as an example for monosaccharides that often do not occur in the chiral pool, has been worked out. The epoxidation of allylic alcohols with tertiary butyl hydroperoxide in presence of titanyl tartaric ester catalysts converts the carbon-carbon double bond stereose-lectively to a diol and is thus ideally suited for the preparation of carbohydrates. The procedure is particularly useful as a repetitive two-carbon homologiza-tion in total syntheses of higher monosaccharides and other poly hydroxy compounds. It starts with a Wittig reaction of a benzylated a-hydroxy aldehyde with (triphenylphosphoran-ylidene)acetaldehyde to produce the olefinic double bond needed for epoxidation. Reduction with sodium-borohydride... 

From the alkoxymagnesium halide derived from a tertiary alcohol (prepared from the alcohol with ethyl-magnesium bromide) with phthalic anhydride in ether or an ether-dioxan mixture. 

Y. Utah, Y. Sasson, I. Shahak, S. Tsaroom, and J. Blum, A new aziridine synthesis from 2-azido alcohols and tertiary phosphines. Preparation of phenanthrene 9,10-imine, J. Org. 

Different reagents such as HX and PX3 may be used to prepare alkyl halides from primary and secondary alcohols. However, because elimination reactions predominate when tertiary alcohols are treated with phosphorous trihalides, preparing tertiary alkyl halides from tertiary alcohols proceeds with good yields only if concentrated hydrogen halides, HX, are used. The reaction of 2-methyl-2-butanol with hydrochloric acid to produce 2-chloro-2-methylbutane (Eq. 14.17) illustrates this transformation. 

Apart from the common heteroatom-derived nucleophiles described, cleavage with other nucleophiles is also possible. For example, reductive cleavage with hydride sources is possible. For ester-linked substrates, Kurth et al. reported an example in which substituted propane-1,3-diols were prepared (Table 1.2, Entry 11). In related work, Chandrasekhar et al. prepared tertiary alcohols by treating an ester-linked substrate with excess Grignard reagent (Table 1.2, Entry 12). If, however, it is desirable to prepare the carbonyl derivative (and not reduce all the way to the corresponding alcohol), then Weinreb-type linker units can be used (Table 1.2, Entries 13 and 14). Treatment of substrates attached via such linkers... 

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