Methanol potassium hydroxide system

Another approach to the l-oxo-l,2-dihydro-j8-carboline system is that due to King and Stiller. When 2-ethoxy carbonyl-3-formyl-indole is condensed with hippuric acid the azlactone 162 is formed, which, with 10% methanolic potassium hydroxide, gives a mixture of the orthoester 163 and the potassium salt 164. 

The methanesulphonic acid content of bromocriptine mesilate is usually determined by titration with 0.1 N methanolic potassium hydroxide. The endpoint may be detected potentiometrically using a glass/calomel electrode system. 

The reactivity of the strained, tricyclic skeleton of the 4,7-oxaeunicellanes was studied by Pietra in 1988 [4]. Treatment of sarcodictyin A (31) with methanolic potassium hydroxide led to the formation of the butenolide 32 (Scheme 4). The Michael acceptor property of the carbon atom C2 favors this rearrangement, leading to a relaxation of the strained ring system. After methanoly-sis of the A-methylurocanate, the newly formed hydroxyl group attacks at C2 and the fragmentation of the carbon-carbon bond between C3 and C4 immediately follows. 

This type of double dehydrobromination has also been used in a few syntheses of 1,6-methano-annulated systems in which the initially formed norcaradiene isomerizes to the corresponding cycloheptatriene derivative. Thus, a good yield of bicyclo[4.4.1]undeca-l,3,5,7,9-pentaene (11, X = H) was obtained by treating the corresponding tetrabromide (9, X = H) with methanolic potassium hydroxide. The 11,11-difluoro analog 11 (X = F) was likewise obtained in 80% yield. The 11,11-dichloro (X = Cl) and 11,11-dibromo (X = Br) analogs, however, were ob-... 

Most 1,2,3-thiadiazines are tetrahydro derivatives that exist as the 1,1-dioxides.12 17 However, the novel, heterocyclic 8n -electron systems 4 and the corresponding 1,2,3-thiadiazines have been prepared.18 Reaction of the 2-chlorocycloalkene-l-carbaldehydes l12 with potassium thiocyanate in aqueous ethanol affords the 2-thiocyanatocycloalkene-l-carbaldehydes 2 which react in the usual fashion with hydrazines to furnish the hydrazones 3a, b. When the hydra-zones 3 a, b are dissolved in 70 % perchloric acid under ice-cooling, hydrogen cyanide is evolved and the 1,2,3-thiadiazinium perchlorates 4a, b crystallize within a short time. Addition of an excess of triethylamine to 4a liberates the 1,2,3-thiadiazine while treatment of 4b with methanolic potassium hydroxide solution furnishes 5 b. 

Penta- and Hexa-aza-compounds. 3,6-Dibenzyl-l,2,4,5-tetrazine (811) undergoes a complex reaction with methanolic potassium hydroxide, giving 3-benzyl-7-methoxy-6-phenylimidazo[l,2-6][l,2,4,5]tetrazine (812), whose structure has been elucidated by X-ray analysis.Carbon-13 n.m.r. spectroscopy has been used to investigate azido-tetrazole valence tautomerism for the systems (813) and (814)" and for (815) (816) (817)." ... 

Humulone (10 g 2.76 x 10 mol) is dissolved in absolute methanol (200 ml). The pH of the solution is adjusted to 5.1 with methanolic potassium hydroxide (2 N). The catalyst (5% platinum(IV) oxide) is added as a suspension in methanol. The hydrogenation is stopped after absorption of 2.35 mols hydrogen. After filtration and removal of the solvent, the residue is separated by counter-current distribution in the two-phase system benzene triethanolamine (15%), ethylene glycol (25%) and HCI 0.25 N (pH 8.4). Dihydrohumulone has a K-value of 1 after 330 transfers and tetrahydrohumulone Is distributed with a K-value of 2. Residual humulone is found in the band with K 0.4. 

In a special case involving a C-ring aza steroid, it was found that epoxida-tion of a A -20-keto grouping using a two-phase system (t-butyl alcohol-aqueous potassium hydroxide-30 % hydrogen peroxide) was much superior to the standard hydrogen peroxide-aqueous methanolic alkali conditions. 

Musumarra et al. [43] identified miconazole and other drugs by principal components analysis of standardized thin-layer chromatographic data in four eluent systems. The eluents, ethylacetate methanol 30% ammonium hydroxide (85 10 15), cyclohexane-toluene-diethylamine (65 25 10), ethylacetate chloroform (50 50), and acetone with the plates dipped in potassium hydroxide solution, provided a two-component model that accounts for 73% of the total variance. The scores plot allowed the restriction of the range of inquiry to a few candidates. This result is of great practical significance in analytical toxicology, especially when account is taken of the cost, the time, the analytical instrumentation and the simplicity of the calculations required by the method. 

Potassium hydroxide when merely dissolved in methanol is not effective in the one-electron reduction of 9-diazofluorene and fluoren-9-ylides. Addition of DMSO to the system makes a drastic change, with the highest efficiency in pure DMSO (Handoo and Kaul 1992, Handoo et al. 1983). 

Oxidative coupling of 2-bromo-4,6-di-im-butylphenol (202, Scheme 51) with potassium hexacyanoferrate(III) in a two-phase system consisting of aqueous potassium hydroxide and benzene affords the dibenzofuranone 203 by the mechanism indicated.The dibenzofuranone 203 is a convenient source of 1-dibenzofuranol (205). On boiling with isopropanol, compound 203 provides the tetra-tert-butyl-l-benzofuranol 204, which may be de-butylated by treatment with aluminum chloride in toluene. 1-Dibenzo-furanol (205) is also obtained by direct treatment of the dibenzofuranone 203 with aluminum chloride in toluene. With boiling methanol, however, compound 203 supplies the methoxy analog 206, which on mild debutylation affords 4-methoxy-1-dibenzofuranol (207). ... 

Sodium ethoxide in ethanol is a suitable base-solvent system for this conversion. Sodium methoxide in methanol or potassium ferf-butoxide in tert-butyl alcohol could also be used, as could potassium hydroxide in ethanol. 

Whereas encapsulation of the small cation Ca2+ ion led to host-guest system 2 with an M/MC = 1 1 stoichiometry, double deprotonation of di-tert-butyl ketipinate H2L2 (1) with 2 N potassium hydroxide and reaction of the dianion (L2)2- with copper(II) chloride in methanol afforded the MC ether sandwich complex [(Kc Cu3(L2)3]2)OMe] (3) with a K/MC = 1 2 stoichiometry (Scheme 1, Fig. 1) [68, 69],... 

Kates et al.8 used a solvent system consisting of 0.001 M tr1methyl amine hydrochloride and 0.001 M potassium hydroxide (pH 9) - methanol (1 4) and a microparticulate silica gel column to separate quinidine and dihydroquinidlne. Cinchonine was used as internal standard. 

Markownikov addition of HQ to the 6,7-double bond (82.206). The resulting chlorolactams possess the same ring system as leuconoxine (74), from Leuconotis eugemfoUus. The structure of275was confirmed by X-ray crystal structure determination (207). A second reaction of considerable interest is that of leuconolam with potassium hydroxide in methanol, which involves the removal of a proton from C-16, followed by internal Michael addition to the 6,7-double bond. The product is the pentacyclic dilactam 277, which contains the meloscine ring system (82). 

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