Aryl-2-propanols

Complementary Examinations. Peak intensity data (obtained from the spectrometer) may be of value in comparative studies (Lundquist et al. 1981). In some cases, peak assignments derived from model compound studies may be verified by decoupling experiments (Lundquist 1979a, 1980, Hauteville et al. 1986) or by the recording and examination of difference spectra (Lundquist and Olsson 1977, Brunow and Lundquist 1980, Lundquist et al. 1981, Adler et al. 1987). 2-D NMR spectroscopic methods may also be used for the same purpose (Lundquist and Stern 1989, Ede et al. 1990). Thus, it was concluded from 2-D COSY H NMR experiments that the peak at S 2.62 in Fig. 5.3.1 is partly due to benzylic protons in 3-aryl-1-propanol units (Lundquist and Stern 1989). 

PMMA is not affected by most inorganic solutions, mineral oils, animal oils, low concentrations of alcohols paraffins, olefins, amines, alkyl monohahdes and ahphatic hydrocarbons and higher esters, ie, >10 carbon atoms. However, PMMA is attacked by lower esters, eg, ethyl acetate, isopropyl acetate aromatic hydrocarbons, eg, benzene, toluene, xylene phenols, eg, cresol, carboHc acid aryl hahdes, eg, chlorobenzene, bromobenzene ahphatic acids, eg, butyric acid, acetic acid alkyl polyhaHdes, eg, ethylene dichloride, methylene chloride high concentrations of alcohols, eg, methanol, ethanol 2-propanol and high concentrations of alkahes and oxidizing agents. 

The dimerization of ketones to 1,2-diols can also be accomplished photochemi-cally indeed, this is one of the most common photochemical reactions. The substrate, which is usually a diaryl or aryl alkyl ketone (though a few aromatic aldehydes and dialkyl ketones have been dimerized), is irradiated with UV light in the presence of a hydrogen donor such as isopropyl alcohol, toluene, or an amine. In the case of benzophenone, irradiated in the presence of 2-propanol, the ketone molecule initially undergoes n — k excitation, and the singlet species thus formed crosses to the T, state with a very high efficiency. 

In recent years, a variety of aryl boronic acids are commercially available, albeit in some cases they may be expensive for large scale purposes. During our work in the mid-1990 s boronic acid (II) was not commercially available and so two different protocols were used to prepare this acid. The first approach involved the transmetallation with n-butyl lithium of aryl bromide (I) and trapping the lithio species generated with trialkyl borate followed by an acid quench. Aryl bromide (I) is easily prepared by reaction of o-bromobenzenesulfonyl chloride with 2-propanol in the presence of pyridine as a base. The second approach was a directed metallation of isopropyl ester of benzene sulfonic acid (VII), to generate the same lithio species and reaction with trialkyl borate. The sulfonyl ester is prepared by reaction of 2-propanol with benzenesulfonyl chloride. From a long-term strategy the latter approach is... 

In general, symmetrical oxo-squaraines having the same end-groups are synthesized by reacting squaric acid with two equivalents of quatemized indolenine, 2-methyl-substituted benzothiazole, benzoselenazole, pyridine, quinoline [39, 45, 46] (Fig. 4) in a mixture of 1-butanol - toluene or 1-butanol - benzene with azeotropic removal of water in presence [39, 45] or absence [47] of quinoline as a catalyst. Other reported solvent systems include 1-butanol - pyridine [48], 1-propanol - chlorobenzene, or a mixture of acetic acid with pyridine and acetic anhydride [49]. Low CH-acidic, heterocyclic compounds such as quatemized aryl-azoles and benzoxazole do not react, and the corresponding oxo-squaraines cannot be obtained using this method [23, 50]. 

Hydrolyses of p-nitrophenyl and 2,4-dinitrophenyl sulfate are accelerated fourfold and eightfold, respectively, by cycloheptaamylose at pH 9.98 and 50.3° (Congdon and Bender, 1972). These accelerations have been attributed to stabilization of the transition state by delocalization of charge in the activated complex and have been interpreted as evidence for the induction of strain into the substrates upon inclusion within the cycloheptaamylose cavity. Alternatively, accelerated rates of hydrolysis of aryl sulfates may be derived from a microsolvent effect. A comparison of the effect of cycloheptaamylose with the effect of mixed 2-propanol-water solvents may be of considerable value in distinguishing between these possibilities. 

Reported structures for homobifunctional aryl azides include a biphenyl derivative and a naphthalene derivative (Mikkelsen and Wallach, 1976), a biphenyl derivative containing a central, cleavable disulfide group (Guire, 1976), and a compound containing a central l,3-diamino-2-propanol bridge between phenyl azide rings that are nitrated (Guire, 1976). The only commercially available homobifunctional photoreactive crosslinker is BASED. 

The group of Ley has reported on the use of palladium-doped perovskites as recyclable and reusable catalysts for Suzuki couplings [151]. Microwave-mediated cross-couplings of phenylboronic acid with aryl halides were achieved within 1 h by utilizing the supported catalyst (0.25 mol% palladium) in aqueous 2-propanol (Scheme 7.127). The addition of water was crucial as attempted transformations in non-aqueous mixtures did not proceed. 

Noyori et al. recently used ESI-MS to characterize species present in catalytically active solutions during the hydrogenation of aryl-alkyl ketones using their base-free catalyst precursors trans-[Ru((R)-tol-BINAP)((R, RJ-dpenJfHXf/ -BH ] (tol-BI-NAP = 2,2 -bis(ditolylphosphino) -1, T-binaphthyl dpen = 1,2-diphenylethylenedia-mine) in 2-propanol [9b]. Based upon ESI-MS observations, deuterium-labeling studies, kinetics, NMR observations, and other results, the authors proposed that the cationic dihydrogen complex trans-[Ru((R)-tol-BINAP)((R, R)-dpen)(H)( 2-H2)]+ is an intermediate in hydrogenations carried out in the absence of base. 

It is well accepted that the asymmetric reduction of simple dialkyl ketones generally proceeds with low enantioselectivity.68 Ohkuma et al.69 reported that hydrogenation of simple ketones can be achieved using Ru(II) catalysts in the presence of diamine and alcoholic KOH in 2-propanol. Promising results have been achieved in the asymmetric hydrogenation of alkyl aryl ketones with a mixture of an Ru-BINAP complex, chiral diamine, and KOH (Scheme 6-33). 

When l-[o-(phenylethynyl)phenyl]cyclopropanol-Co2(CO)6 complex (36) is heated at 50 °C in 2-propanol under argon in the presence of DABCO, a completely different product, 3a,4-dihydro-3ff-cyclopenta[a]inden-2-one derivative 40, is produced as a 95 5 diastereomeric mixture in 72% yield. As shown in Scheme 18, not only aryl-substituted alkynyl derivatives, but also alkyl-substituted alkynyl derivatives, give the corresponding cyclopenta[a]inden-2-one derivatives 40 in moderate to good yields. 

The Friedel-Crafts alkylation of aromatic compounds by oxetanes in the presence of aluminum chloride is mechanistically similar to the solvolyses above, since the first step is electrophilic attack on the ring oxygen by aluminum chloride, followed by a nucleophilic attack on an a-carbon atom by the aromatic compound present. The reaction of 2-methyloxetane and 2-phenyloxetane with benzene, toluene and mesitylene gave 3-aryl-3 -methyl-1-propanols and 3-aryl-3-phenyl-l-propanols as the main products and in good yields (equation 27). Minor amounts of 3-chloro-l-butanol and 4-chloro-2-butanol are formed as by-products from 2-methyloxetane, and of 3-phenyl-l-propanol from 2-phenyloxetane (73ACS3944). 

Truchot17 1 reported in 1865 that epicblorohydrin (Eq. 918) cnnlcl likewise be condensed with several aryl chlorides, giving ester of l, l dichloro-2-propanol. Bedoa10 later showed that eydohexenc <>Nrdc... 

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