Alcohol,tert

Methyl-substituted primary alcohols can be separated after derivatization with [6-methoxy-2,5,7,8-tetramethylchromane-2-carboxylic acid] (Trolox M methyl ether) [13] while sec.- and tert.-alcohols are derivatized with 2-dimethylamino-l,3-dimethyl-octahydro-lf/-l,3,2-benzodiazaphosphole [14] (Eig. 7-5). 

Based on the extraordinary selectivity in hydrosilylation reactions when an alkyne competes with other groups for a silicon-bonded active hydrogen, further derivatisation can be carried out. The hydrosilylation of 2-methyl-3-butynol, which works very well with polymeric siloxanes, gives hydroxyal-kenylsilicon compounds - a l-silylalkenyl/2-silylalkenyl mixture from cis-addition across the triple bond. Elimination of water from the tert. alcohol produced, catalyzed by traces of a strong acid, results in isoprenylic siloxanes in more than 90 % overall yield (Eq. 8). 

Hydrogenolysis of tert-alcohols.1 2 3 This deoxygenation can be effected with Raney Ni slurry (Aldrich 50% slurry in water) that has been washed eight times with distilled water and twice with 1-propanol. Thus reaction of a tertiary alcohol with washed Raney Ni for a short time yields a mixture of alkenes that furnish a single alkane on hydrogenation catalyzed by Pd/C. 

Scheme 21 Miller s tetrapeptide catalyzed KR of tert-alcohols [166]...

Bases, such as potassium or sodium hydroxide, piperidine, and pyridine, react with primary and secondary hydroperoxides to form aldehydes or ketones. fert-Alkyl hydroperoxides form stable alkali metal salts with caustic however, when equimolar amounts of the hydroperoxide and its sodium salt are present in aqueous solution, rapid decomposition to tert-alcohol and oxygen occurs. 

From acid chlorides and alcohols RCOCI + R OH — RC02R + HCi Versatile reaction works well with prim., sec., and tert. alcohols a base may be necessary to remove HCI, because tert-aliphatic alcohols may give alkenes and fert-butyl chlorides. 

Permonosulfuric acid solutions, H2SOs, in organic media (some lower alcohols and acetonitrile). Explosive reactions are possible with sec and tert alcohols and generally in cases of too high concentrations of the peracid (Ref 11)... 

Contact of the acid with sec- or tert-alcohols, even with cooling, may lead to violent explosions [1]. The autodetonation region which exists for the hydrogen peroxide— sulfuric acid—2-propanol or —ferf-butanol system is shown on a triangular diagram [2]. 

In this process, epoxidation of the double bonds was followed by reduction to obtain the tert-alcohol which was esterified with methacryloyl chloride in the subsequent step. While epoxidation was found to be close to quantitative based on double bond content, reduction was incomplete and the residual epoxy functional PIB (24-47%) had to be separated by column chromatography before esterification. It should be noted that this macromonomer was a tert-ester which might be quite unstable in acidic conditions, and is also more hindered than the... 

Deoxygenative reduction can be carried out at room temperature with Et3B as an initiator [19,20]. However, this reaction is limited to thiocarbonates derived from sec- and tert-alcohols, since the C-0 bond cleavage of thiocarbonates derived from pr/m-alcohols does not occur easily at room temperature. 

Synthesis of unsymmetrical sec- and tert-alcohols. An attractive route to these alcohols involves a one-pot acylation (13,210) of RMnBr followed by reaction with an alkyllithium (14, 229). The overall yield is generally higher than that obtained by reaction of the alkyllithium with the isolated, intermediate ketone. An example is the synthesis of a-bisabolol (2) from the homoallylic manganese bromide 1. These RMnBr reagents can be prepared from RLi using MnBr2, which... 

Tetrahydropyranylation of tert-alcohols.2 The reaction of ten-alcohols with dihydropyran in CH2C12 at 0° catalyzed by this reagent provides tetrahydropyranyl ethers in 78-96% yield. 

By interaction of alkyllithium with 2-methylthiirane, active centres are produced in the form RS"Li+. With monomer these centres yield polypropy-lenesulphide. In the presence of lithium tert.-alcoholates, complexes of the shape... 

Selenium dioxide (SeOa) in tert-alcohols has been widely used for the dehydrogenation of 3-0x0 steroids, and particularly in the conversion of A -3-ketones into A dienones [240]. Other steroidal ketones suffer similar a,jS -dehydrogena-tion e.g. i2-ketones [241] and a 4,4-dimethyl-7-ketone [242]), but the same reagent in different solvents will also effect oxidation of certain steroidal ketones with adjacent methylene groups ( C0-CH2 ) into a -diketones (-CO CO-), a reaction which is common outside the steroid field. In ethanolic solution, for example, 5a-cholestan-3 one was oxidised by SeOa to give 5a-cholestane-2,3-dione [243], isolated in its enoHc forms. 

WESTPHALEN - LETRE E Rearrangement Cartxx tion rearrangement of steroidal tert alcohols (saeWagner-Meerwein). 

Among the other benzyloxycarbonyl derivatives the Z(OMe) group shows a slightly higher acid-lability than the Boc group and may find occasional use for N -protection instead of the Boc group when tert-alcohol-derived groups are selected for semipermanent side-chain protection. 

In view of what has been discussed in the previous section (see Section II.A.2) on the influence of the halide in Grignard reagents, it is of interest to mention that Leroide reported the formation of considerably more of the reduction reaction product when the iodide was used, when compared with the results obtained with the chloride and the bromide. The yield ratios of secondary alcohol versus tertiary alcohol were (sec. alcohol tert. alcohol) 1.2,2.1, and 10, respectively, for the chloride, bromide, and iodide Grignard reagent. 

Carbonylation of trialkylboranes in the presence of ethylene glycol results in migration of a second and a third alkyl group to give, after oxidation, the corresponding tert-alcohols. ... 

Mukaiyama, T., Shintou, T., Fukumoto, K. A Convenient Method for the Preparation of Inverted tert-Alkyl Carboxylates from Chiral tert-Alcohols by a New Type of Oxidation-Reduction Condensation Using 2,6-Dimethyl-1,4-benzoquinone. J, Am, Chem, Soc, 2003,125, 10538-10539. 

Scheme 37 Formation of the 14-alkenyl derivatives 116 from sec- or tert-alcohols 115 after treatment with acid...

H-Mordenite catalyzes the smooth conversion of simple aldehydes and alcohols to form acetals at 30° in the liquid phase. From the examples in Table XXVII, it is apparent that in these heterogeneous catalytic systems, acetal formation is dependent on the structures of both the aldehyde and the alcohol involved. Thus, for a given aldehyde, yields of acetal decreased in the order primary > secondary > tertiary that is, branching at the a-carbon of the alcohol reduced the equilibrium conversion to acetal. In the isobutyraldehyde reactions, an extremely sharp drop in conversion was observed upon changing from isopropanol to fert-butanol as reactant. This observation suggests that, in addition to the increased steric interactions between organic reactants encountered in the tert alcohol system, molecular sieving-type interactions within the narrow mordenite pore system are operative. 

We selected carboxylic acid groups as the main component of weakly acidic cation exchange groups, rather than sulfonic acid amide with a dissociable hydrogen, phosphonic acid, phenolic hydroxide or perfluoro-tert-alcohol exchange sites, from the viewpoint of ease of preparation, stability and good performance in electrolysis,... 

Direct room temperature esterification of carboxylic acids with alcohols, including tert. alcohols with the help of dicyclohexylcarbodiimide (DCC) and 4-diakylaminopyridine catalysts 3. 

Dehydration of tert-alcohols.2 This reaction can be effected with BF3 etherate (1-3 equiv.) in CH2CI2 at 25°. Yields are usually higher than those obtained with the Burgess reagent, thionyl chloride/amine, or p-tolucncsulfonic acid. When dehydration could result in two different alkencs, the more thermodynamically stable alkenc predominates. Noepcntyl tert-alcohols result in mixtures of alkencs, some resulting from a carbocation rearrangement. 

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