Benzylic alcohols Subject

In 1899 Thoms isolated an alcohol from Peru balsam oil, which he termed peruviol. This body was stated to have powerful antiseptic properties, but has not been further investigated until Schimmel Co. took up the subject. The oil after saponification was fractionated, and after benzyl alcohol had distilled over, a light oil with characteristic balsamic odour passed over. It boiled at 125° to 127° at 4 mm., and had a specific gravity 0 8987, optical rotation -1- 12° 22, and refractive index 1-48982. This body appeared to be identical with Hesse s nerolidol, whilst in physical and chemical properties it closely resembles peruviol. The characters of the various preparations were as follows —... 

The chemistry of indium metal is the subject of current investigation, especially since the reactions induced by it can be performed in aqueous solution.15 The selective reductions of ethyl 4-nitrobenzoate (entry 1), 2-nitrobenzyl alcohol (entry 2), l-bromo-4-nitrobenzene (entry 3), 4-nitrocinnamyl alcohol (entry 4), 4-nitrobenzonitrile (entry 5), 4-nitrobenzamide (entry 6), 4-nitroanisole (entry 7), and 2-nitrofluorenone (entry 8) with indium metal in the presence of ammonium chloride using aqueous ethanol were performed and the corresponding amines were produced in good yield. These results indicate a useful selectivity in the reduction procedure. For example, ester, nitrile, bromo, amide, benzylic ketone, benzylic alcohol, aromatic ether, and unsaturated bonds remained unaffected during this transformation. Many of the previous methods produce a mixture of compounds. Other metals like zinc, tin, and iron usually require acid-catalysts for the activation process, with resultant problems of waste disposal. 

Sulphated zirconia catalysts can be acidic or superacidic depending on the method of treatment. A variety of acid-catalysed reactions, referred to earlier in this section, can be carried out with sulphated zirconia. Yadav and Nair (1999) have given a state-of-the art review on this subject. Examples of benzylation of benzene with benzyl chloride / benzyl alcohol, alkylation of o-xylene with. styrene, alkylation of diphenyl oxide with 1-dodecene, isomerization of epoxides to aldehydes, acylation of benzene / chlorobenzene with p-chloro benzoylchloride, etc. are covered in the review. 

The cooled reaction product is treated with 200 cc. of water, the layer of oil separated, washed once with a second portion of water, and subjected to distillation in vacuo. The first fraction of the distillate contains benzyl alcohol together with unchanged aldehyde, as well as a small quantity of water. The temperature then rises rapidly to the boiling-point of benzyl benzoate, when the receivers are changed. The product boils at 184-185°/15 mm., and analysis by saponification shows it to consist of 99 per cent ester. A yield of 410-420 g. is obtained, which corresponds to 90-93 per cent of the theoretical amount. This benzyl benzoate supercools readily, but after solidifying... 

Discussion An effort to see if the skin was permeable to BZ. We used benzyl alcohol as the vehicle in 31 cases and Cresol/N-ethylmorpholine in 12 cases. We limited the freguency of examination since most subjects showed no significant changes except at the highest dosage. Noticeable effects appeared mostly after a delay of 24 hours, suggesting that the percutaneous route is relatively ineffective. Estimated Intensity of response was only 5-10% of that observed by the intravenous route, but duration of effects was similar (after the 24-hour delay). 

Protodedeuteration reaction has, however, some limitations. It cannot be used to study compounds subject to secondary condensation in acidic medium, such as certain benzyl alcohol and benzyl ether derivatives. Moreover, the partial rate factors depend greatly on the medium used because different acids show different degrees of selectivity. For instance, the reported partial rate factors for the para position of toluene (/PMe) range from 170 (in sulfuric acid at 6S°C.) (13) to 4000 (in hydrogen bromide) 22). 

The reaction may alternatively be carried out by boiling the benzaldehyde vigorously under reflux for 2 hours with a solution of 20 g of potassium hydroxide in 90 ml of water, and then working up the cooled reaction mixture as described above. Reaction is normally complete under these conditions the extent of the reaction may be determined by subjecting the crude ether extract, before the latter is washed with bisulphite solution, to g.l.c. analysis on a 1.5 m column of Chromosorb W with 10 per cent of Carbowax as the stationary phase, at 156 °C with a nitrogen flow rate of 40ml per minute. The retention times of benzaldehyde and benzyl alcohol are approximately 2.7 and 9.7 minutes respectively. 

Although significant improvements have been made in the synthesis of phenol from benzene, the practical utility of direct radical hydroxylation of substituted arenes remains very low. A mixture of ortho-, meta- and para-substituted phenols is typically formed. Alkyl substituents are subject to radical H-atom abstraction, giving benzyl alcohol, benzaldehyde, and benzoic acid in addition to the mixture of cresols. Hydroxylation of phenylacetic acid leads to decarboxylation and gives benzyl alcohol along with phenolic products [2], A mixture of naphthols is produced in radical oxidations of naphthalene, in addition to diols and hydroxyketones [19]. 

Vertaline (61) was synthesized through two routes that involve an W-acylimin-ium ion cyclization (20) and an intermolecular [3 + 2] cycloaddition (21,22) as the key steps, respectively. Model studies (20, 24) for assembling the quinolizi-dine moiety by the W-acyliminium ion cyclization are shown in Scheme 7. The benzyl alcohol 65 was converted to glutarimide 66 by the Mitsunobu procedure in 55% yield. Reduction of imide 66 with diisobutylaluminum hydride afforded 67, which was subjected to V-acyliminium cyclization to give the lactam 68 in 40% overall yield from 66. Lactam 68 possesses the correct stereochemistry at all chiral centers required for vertaline (61). 

The details of the reaction conditions used in this study have been described elsewhere (Dershem, S. M., et al., Holzforschung Fisher, T. H., et al., J. Org. CAem., in press). To test the importance of a p-hydroxyl substituent, the kinetics of oxidation of three benzyl alcohols p-hydroxybenzyl alcohol, (1), m-hydroxybenzyl alcohol, (2), and 4-hydroxy-3-methoxybenzyl alcohol, (3), were examined under alkaline nitrobenzene oxidation conditions. Some l-(4-hydroxyphenyl)-2-(4 -substituted phenyl)ethanols, (4), were synthesized as / -l lignin model compounds and subjected to alkaline nitrobenzene oxidation at 120 °C to study substituent effects. For controls, some of these compounds were reacted with or without nitrobenzene, alkaline catalyst, or water. In an effort to determine the effects of substituents on the oxidative-cleavage reaction of 4-hydroxystilbenes (5), a series of competitive rate experiments using both nitrobenzene and copper(II) as the oxidants in 2N NaOH was performed (Dershem, S. M., et al., Holzforschung, in press). 

Caldarelli et al. (240) have recently reported a five-step synthesis of substituted p)Trole libraries L22 and L23 using solid-supported reagents and scavengers. The synthesis involved oxidation of benzyl alcohols Mi to aldehydes (step a, Fig. 8.46), Henry reaction of aldehydes 8.91 with nitroalkanes M2 (step b), and acylation and elimination of nitroalcohols 8.93 (steps c and d) to give the nitrostyrenes 8.94, which were subjected to 1,3-dipolar cycloaddition with an isocyanoacetate (step e) to give the pyrroles 8.95. N-alkylation of these pyrroles with alkyl halides (step f) and final library-from-a-library hydrolysis/decarboxylation of L22 gave a library of trisub-stituted pyrroles L23 (step g. Fig. 8.46). 

A mixture of benzyl alcohol (21.6 g, 0.20 mol) and 1,1-dichloroethene (26,2 g, 0.27 mol) was added dropwise over a period of 30 min to anhyd HF (75 mL) with mixing and cooling to - 78 C. Then the temperature was gradually raised to 0 C. After 3 h the mixture was poured onto iee. neutralized with NHj, and extracted with EtjO. After the EtjO had been distilled off, the mixture was subjected to fractional distillation yield ... 

Danishefsky and Harvey have reported the synthesis of an important subunit in the construction of tirandamycin (Scheme 51). Trimethylsilyl diene (14) reacts with 4,5-dimethylfuran-2-carbaldehyde (184) followed by a brief treatment with TFA to give exclusively the syn pyrone (185). Pyrone (185) is reduced using LAH and subjected to a Ferrier-like rearrangement using benzyl alcohol in the presence of... 

Oxyfluoroalkylation. Benzylic alcohols containing a CH2C F2 +i chain are formed when styrenes are subjected to photooxygenation in the presence of (Bu3Sn)2. 

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