Camphor bromo

In recent years, several modifications of the Darzens condensation have been reported. Similar to the aldol reaction, the majority of the work reported has been directed toward diastereo- and enantioselective processes. In fact, when the aldol reaction is highly stereoselective, or when the aldol product can be isolated, useful quantities of the required glycidic ester can be obtained. Recent reports have demonstrated that diastereomeric enolate components can provide stereoselectivity in the reaction examples include the camphor-derived substrate 26, in situ generated a-bromo-A -... 

Brom-jod, n. iodine bromide, -kalium, n. potassium bromide, -kalzium, n., kalk, tn. calcium bromide, -kampher, tn. bromo-camphor, Pharm.) monobromated camphor, -kohlenstoff, tn. carbon (tetra)bromide. -korper, tn. Colloids) "bromide body (bromide ion), -kupfer, n. copper bromide, lauge, /. bromine lye (solution of sodium hypobromite and bromide made by passing bromine into sodium hydroxide solution), -lithium, n. lithium bromide. -Idsung, /. bro-nune solution, -magnesium, n. magnesium bromide. -metall, n. metallic bromide. 

The Gabriel-Cromwell aziridine synthesis involves nucleophilic addition of a formal nitrene equivalent to a 2-haloacrylate or similar reagent [29]. Thus, there is an initial Michael addition, followed by protonation and 3-exo-tet ring-closure. Asymmetric variants of the reaction have been reported. N-(2-Bromo)acryloyl camphor-sultam, for example, reacts with a range of amines to give N-substituted (azir-idinyl)acylsultams (Scheme 4.23) [30]. 

Camphor reduction, a-bromo ketone to ketone, 127 Carbenium ions ... 

Photolysis of the blue solid (+)-10-bromo-2-chloro-2-nitrosocamphane (270) with red light produces two nitroxide radicals 271 and 272 and 10-bromo camphor 273, 10-bromo-2-chloro-2-nitro camphane 274 in addition to some minor products (equation 122). A complex reaction mechanism has been proposed144. 

Diastereoselective alkylation of (R)-(-F)-camphor-based glycylimine (19) with 3-bromo-2-fluoropropene gave (R)-(-F)-2-amino-4-fluoropent-4-enoic acid with 38% overall yield and 90% ee after hydrolytic deprotection, or in the case of the alanylimine, (R)-(-F)-2-amino-4-fluoro-2-methyl-pent-4-enoic acid (19% overall yield, 59% ee) [49]. Deprotection under drastic conditions was accompanied by hydrolysis of the fluorovinyl moiety to give (R)-(-)-2-amino-4-oxo-pentanoic acid hydrochloride with 28% overall yield and >95% ee (Scheme 4). 

X-Ray diffraction studies of ( )-carbocamphenilone," of (-)-camphene-8-carboxylic acid," and of a number of Money s brominated camphor derivatives (Vol. 6, p. 39 Vol. 7, p. 40) have been published they include 8-bromo-camphor," l,7-dibromo-3,3,4-trimethylnorbornan-2-one, l,7-dibromo-4-... 

A camphor-based 3-acyl-2-oxazolidinone has also been used for diastereoselective alkylations66. The A-acylated auxiliary 18 is prepared in three steps from 7,7-dimethyl-2-oxobicy-clo[2.2.1]heptane-l-carboxylic acid (ketopinic acid, 17)67. Deprotonation by lithium diiso-propylamide in tetrahydrofuran at — 78 °C and subsequent alkylation with activated halides [(bromo- or (iodomethyl)benzene, 3-bromo- or 3-iodopropene] furnished moderate to good yields of alkylation products in high diastereomeric ratios (>97 3 by H NMR). With added hexamethylphosphoric triamide the alkylation yields are increased and bromoalkanes also give satisfactory yields. The diastereomeric ratios are, however, much lower (d.r. 70 30 to 85 15)67. 

The 1-dichloro-d-bromo-camphor sulphonie salts are the least soluble. The colour of these optically active derivatives is the same as that of the racemic salts. 1-Dichloro-diethylenediamino-chromie d-a-bromo-camphor sulphonate, [Cren2Cl2]SO3C10H14OBr, forms small, shining violet crystals, and has specific rotation [molecular rotation of [M]D + 176-9°. Solutions of both isomers are rapidly raeemised. 

The resolution was carried out by means of d-bromo-camphor-sulphonie acid. The salts of the bromo-series are more easily resolved on account of the great difference between the isomeric d-bromo-camphor sulphonates. In both series the d-bromo-eamphor sulphonate of the d-isomer is more sparingly soluble. These active compounds are very stable, and aqueous solutions of the bromides of the bromo-ammine series may be kept for a considerable time at ordinary temperatures, and even on heating to boiling racemisation does not occur. If the bromine in the complex be removed by means of silver nitrate activity... 

In 1913 Werner 2 described a new series of optically active cobalt compounds containing two asymmetric cobalt atoms in the molecule, the tetraethylenediamino-/i-amino-nitro-dicobaltic salts. The resolution is effected by treating tetraethylencdiamino - /x - amino - nitro-dicobaltic bromide with silver d-bromo-camphor sulphonate and fractionally crystallising the product. 

Three different d-bromo-camphor sulphonates are obtained, namely, (1) an inactive crystalline salt containing eight molecules of water of hydration, from which a series of hevo-salts can be prepared (2) an active crystalline form with seven molecules of water of hydration, yielding a series of meso-salts and (3) another active form with six molecules of hydration, yielding a series of dextro-salts. 

Tetraethylenediami.no - - amino - nitro - dicobaltic d-bromo-camphor Sulphonate,... 

The nitrate is transformed into the bromide, and this is then treated with active silver bromo-camphor sulphonate. A dark green solution is formed, and a difficultly soluble bromo-camphor sulphonate mixed with silver salt. This mixture is extracted with hot water and the solution so obtained fractionally crystallised. The resolution is tedious and the yield is not good. 

Optically Active Dodecammino-hexol-tetra-cobaltic Salts.3— These salts may be resolved by means of bromo-camphor sulphonic acid. Dodecammino-hexol-tetracobaltic chloride is mixed with silver bromo-camphor sulphonate, whereby all the chlorine is precipitated as silver chloride and the solution treated with dilute acetic acid. The ilrst crop of d-bromo-camphor sulphonate is laevo-rotatory, that from 1-bromo-eamphor sulphonate dextro-rotatory. 

Two series of complex iridium salts corresponding to the hexammino-and diacido-iridium salts have been prepared containing ethylene-diamine. These have the same general characteristics as the ammino-salts. Both series have been resolved into optically active isomers, the dinitrito-series by means of d- and 1-bromo-camphor sulphonic acid, and the triethylenediamino-series by d- and 1-nitro-camphor. Attempts have been made to prepare etliylenediamino-derivatives containing tetravalent iridium. Thus, sodium hexaehloro-iridate, [IrCl6]Na2, reacts with ethylenediamine, but the products are syrupy and cannot be purified. Derivatives of trivalent iridium, however, have been prepared. These are crystalline and fairly easily purified. The... 

The bromo-camphor sulphonate, [Ir en2(NO2)2][d-C10H14O4BrS], is prepared by treating the iodide with silver bromo-camphor sulphonate. It separates as a vitreous mass. 

Theoretically two dinitro-series are possible, but only one has been obtained, and, as the bromo-camphor sulphonate is separable into two optically active components, the series prepared is regarded as the cis-, or 1-, 2-series. 

Solvent Norbor- 3-Bromo- 3-Bromo 3-Methyl- 1-Methyl- Camphor 3-Bromo- 9,3-Di- Fenchone Camphene... 

Canadian workers have been exploring methods for the conversion of cheap and readily available camphor into enantiopure cyclopentane derivatives for use in terpene and steroid synthesis, e.g. 1 — 2. In a recent extension of these studies, em/o-3-bromo-4-methylcamphor 3 (0.1 mol) was... 

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