2.6- Dichloro-4- alcohols

Reinecke compared the effects of two bases, potassium hydroxide and triethylamine, on the dehalogenation of dichlormethyl-substituted cyclohexanones over 10% Pd-C in methanol.207 Dehalogenation of 4-dichloromethyl-4-methylcyclohexanone proceeded smoothly in the presence of potassium hydroxide to give primarily 4,4-di-methylcyclohexanone, while in the presence of triethylamine, in addition to 4,4-dimethylcyclohexanone and a little partially dechlorinated material, an approximately equal amount of stereoisomeric 4-dichloromethyl-4-methylcyclohexanols was isolated. Since the dichloro alcohols were rapidly dehalgenated to 4,4-dimethylcyclo-hexanol in the presence of potassium hydroxide, the inertia of the chlorine atoms in the dichloro alcohols was considered to be due to the presence of triethylamine (eq. 13.112). 

Glycerol ct-dichlorohydrin, sym-dichloroiso-propyl alcohol, 1,3-dichloro-2-hydroxypropane, CH2CI-CHOH-CH2C1. Colourless liquid with an ethereal odour b.p. 174-175" C. Prepared by passing dry HCl into glycerin containing 2% elhanoic acid at 100-1 lO C. Converted to x-epichlorohydrin by K.OH, Used as a solvent for cellulose nitrate and resins. 

Glycerol -dichlorohydrin, 2.3-dichloro-propanol, CH2CI CHC1 CH2 0H. Colourless liquid, b.p. 182 C. Prepared by the chlorination of propenyl alcohol. Oxidized by nitric acid to 1,2-dichloropropionic acid. Reacts with NaOH to give epichlorohydrin. 

Silyl ethers serve as preeursors of nucleophiles and liberate a nucleophilic alkoxide by desilylation with a chloride anion generated from CCI4 under the reaction conditions described before[124]. Rapid intramolecular stereoselective reaction of an alcohol with a vinyloxirane has been observed in dichloro-methane when an alkoxide is generated by desilylation of the silyl ether 340 with TBAF. The cis- and tru/u-pyranopyran systems 341 and 342 can be prepared selectively from the trans- and c/.y-epoxides 340, respectively. The reaction is applicable to the preparation of 1,2-diol systems[209]. The method is useful for the enantioselective synthesis of the AB ring fragment of gambier-toxin[210]. Similarly, tributyltin alkoxides as nucleophiles are used for the preparation of allyl alkyl ethers[211]. 

C6H4CL2 P-DICHLORO- 21.345 1.8209E-01 1.0115E-05 77.15 281 C6H140 HEXYL-ALCOHOL -322.910 6.0346E-01 5.1175E-05 -137.95... 

Oppenauer oxidation, 236 Oxidation of allylic alcohols with dichloro-dicyanobenzoquinone, 248 Oxidation of allylic alcohols with manganese dioxide, 247... 

Miller et al. [9] hypothesized rules on the regioselectivity of addition from the study of the base-catalyzed addition of alcohols to chlorotnfluoroethylene. Attack occurs at the vinylic carbon with most fluorines. Thus, isomers of dichloro-hexafl uorobutene react with methanol and phenol to give the corresponding saturated and vinylic ethers The nucleophiles exclusively attack position 3 of 1,1-dichloro-l,2,3,4,4,4-hexafluoro-2-butene and position I of 4,4-dichloro-l,l,2,3,3,4-hexafluoro-1-butene [10]. In I, l-dichloro-2,3,3,4,4,4-hexafluoro-l-butene, attack on position 2 is favored [J/] (equation 5) Terminal fluoroolefms are almost invariably attacked at tbe difluoromethylene group, as illustrated by the reaction of sodium methoxide with perfluoro-1-heptene in methanol [/2J (equation 6). 

The addition of nucleophiles to cyclic fluoroolefins has been reviewed by Park et al. [2 ]. The reaction with alcohols proceeds by addition-elimination to yield the cyclic vinylic ether, as illustrated by tlie reaction of l,2-dichloro-3,3-di-fluorocyclopropene Further reaction results in cyclopropane ring opening at the bond opposite the difluoromethylene carbon to give preferentially the methyl and ortho esters of (Z)-3-chloro-2-fluoroacrylic acid and a small amount of dimethyl malonate [29] (equation 8). 

Sodium methyl mercaptide in xylene was reported to react (25°, 2 hr) in a stepwise fashion with 3,5-dichloro-as-triazine to yield the 3-methylthio-5-chloro and then (70°, 2 hr) the 3,5-bis-methylthio derivatives. However, the structure of the former is very likely to be 307. With dimethylamine in benzene (25°, 5 min), ethyleneimine in ether (25°, 3 min), and alcoholic ammonia (25°, few min), this dichloro derivative was assumed to form 3-amino derivatives. The high reactivity of as-triazines is demonstrated by the facile ethoxylation... 

Dichloro-s-triazine and its 6-alkyl analogs are as easily hydrolyzed by water as trichloro-s-triazine and, on suspension in aqueous ammonia (25°, 16 hr), the first is diaminated in good yield. 2,4-Bistrichloromethyl-6-methyl- and -6-phenyl-s-triazines (321) require a special procedure for mono-alkoxylation (0-20°, 16 hr, alcoholic triethylamine) disubstitution occurs at reflux temperature (8 hr). Aqueous triethylamine (100°, 3 hr) causes complete hydroxy-lation of 2,4,6-tris-trichloromethyl-s-triazine which can be mono-substituted with ammonia, methylamine, or phenoxide ion at 20°. 

Displacement of bromine on phenacyl halide with imidazole gives Reduction with sodium borohydride followed by displacement with 2,6-dichloro-benzyl alcohol in HMPA then produces antifungal orconazole (37). ... 

After drying, 15 parts of 5,7-dichloro-8-hydroxy-quinaldine melting at 111°C to 112°C are obtained. When recrystalliaed from alcohol,the product is obtained in voluminous,slightly yellowish needles having the melting point of 1115°C to 112°C. 

The isomer 2,4 -dioxy-3,3 -dichloro-diphenyl-(2-pyridyl)-methane is removed by thoroughly washing with 430 ml of 95°C boiling alcohol, obtaining 167 g of isomer-free product (yield 69%). The 3,3 -dichloro-4,4 -dioxy-diphenyl-(2-pyridyl)-methane is a white solid, crystallizing from 95% alcohol MP 212° to 215°C. 

Preparation of 4,4 -Dioxy-Diphenyl-(2-Pyridyl)-Methane 100 g of 3,3 -dichloro-4,4 -dioxy-diphenyl-(2-pyridyl)-methane, obtained as above described, are dissolved in 660 ml of 10% sodium hydroxide and 49 g of Raney-nickel alloy are added to the solution with vigorous stirring, at room temperature and during 4 hours. The mixture is stirred overnight at room temperature, then it is filtered and brought to pH 5 with 10% acetic acid. The precipitate obtained, filtered, washed and dried is then dissolved in 1,500 ml of 95°C boiling alcohol to eliminate the insoluble salts. The residue obtained after the evaporation of the alcoholic solution weighs 74 g (yield 92%). The yield in respect to 2-pyridinaldehyde is 63.5%. 

Q Primary alcohols can be oxidized to give aldehydes (Section 17.7). The reaction is often carried out using pyridinium chlorochromate (PCC) in dichloro-methane solvent at room temperature. 

Notable examples of general synthetic procedures in Volume 47 include the synthesis of aromatic aldehydes (from dichloro-methyl methyl ether), aliphatic aldehydes (from alkyl halides and trimethylamine oxide and by oxidation of alcohols using dimethyl sulfoxide, dicyclohexylcarbodiimide, and pyridinum trifluoro-acetate the latter method is particularly useful since the conditions are so mild), carbethoxycycloalkanones (from sodium hydride, diethyl carbonate, and the cycloalkanone), m-dialkylbenzenes (from the />-isomer by isomerization with hydrogen fluoride and boron trifluoride), and the deamination of amines (by conversion to the nitrosoamide and thermolysis to the ester). Other general methods are represented by the synthesis of 1 J-difluoroolefins (from sodium chlorodifluoroacetate, triphenyl phosphine, and an aldehyde or ketone), the nitration of aromatic rings (with ni-tronium tetrafluoroborate), the reductive methylation of aromatic nitro compounds (with formaldehyde and hydrogen), the synthesis of dialkyl ketones (from carboxylic acids and iron powder), and the preparation of 1-substituted cyclopropanols (from the condensation of a 1,3-dichloro-2-propanol derivative and ethyl-... 

With the iodine atom in its proper place, provisions for construction of the C9-C10 bond by an aldol reaction could be made (see Scheme 44). To this end, oxidative cleavage of the para-methoxy-benzyl ether in 181 with 2,3-dichloro-5,6-dicyano-l,4-benzoqui-none (DDQ) in CH2CI2-H2O furnishes a primary alcohol that can... 

Apart from ethanol, other primary alcohols catalyse the formation of the dichloro complex, probably via a rhodium(I) intermediate rather than a rhodium(III) hydride. Rhpy4X2" compounds have anti-bacterial activity. 

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