Cyclopropyl bromide

The reaction of cyclopropyl bromide with triphenylphosphine gives the expected phosphonium salt in less than 1 % yield. An alternate route to the salt by the thermal decomposition of 2-oxo-3-tetrahydrofuranyltriphenylphosphonium bromide gives a... 

Cyclopentanepropanoic acid, c405 Cyclopentene oxide, e42 Cyclopentyl bromide, b313 Cyclopentyl chloride, c93 Cyclopropyl bromide, b314 Cyclopropyl cyanide, c407... 

Cyclophanes, 24 37-38 Cyclopropanes, 13 654 26 654 Cyclopropenyl acids, 5 28 Cyclopropylamine (CPA) in nevirapine synthesis, 15 741-742 physical properties of, 2 498t Cyclopropyl bromide, physical properties of, 4 350t... 

Cyclopropyl carbanions are capable of maintaining their configuration whereas the CT-radical has been shown to reach inversion equlibrium with a rate constant of lO" s". ITie cyclopropyl bromide 13, and the corresponding iodide, are reduced in a single two-electron polarographic wave and the S +)-isomer yields the R(-)-hydrocarbon with 26% enantiomeric excess [67, 68]. Such a substantial retention of configuration during reduction of the carbon-bromine bond indicates a very fast second electron transfer process. Results from reduction of the cyclopropyl bro-... 

Ciprofloxacin Ciprofloxacin, l-cyclopropyl-6-fluoro-l,4-dihydro-4-oxo-7-(l-piper-azinyl)-3-qninolincarboxylic acid (33.2.19), is synthesized in a completely analogous scheme, except that instead of using ethyl iodide in the alkylation stage, cyclopropyl bromide is nsed [76-78]. 

Since the carbon-carbon bonds in strained cyclopropane rings have large s-character, cyclopropyl bromides underwent smooth bromine-magnesium exchange by the action of lithium tributylmagnesate (equation 27)". 

Synthesis (a) Its preparation is the same as that for naloxone starting from oxycodone via the intermediate i except that the nitrogen atom is alkylated with cyclopropyl bromide (Blumberg et al. (Endo Laboratories), 1967 1973 Drugs Fut. 1977 2000 Kleemann et al. 1999) ... 

In 1994, Buzek et al. (109) reported that the allyl cation could be prepared from a variety of halide precursors, e.g., allyl chloride or cyclopropyl bromide, on SbF5 at cryogenic temperature, based on the infrared spectrum of the products. Those workers challenged BGW s claim of the persistent allyl cation based on the discrepancy between the isotropic 13C shift in the zeolite and that calculated at MP2/6-31G. This was one of the first examples of the use of chemical shift calculations to interpret (and in this case challenge) an NMR study of a species on a solid acid. 

Even dicyclopropylbromonium ion 136 has been prepared357 by the ionization of cyclopropyl bromide in SbFs-SCPGF solution at low temperature. Also a series of alkylcyclopropylhalonium ions 137 and 138 has been studied.357... 

In a modification of Julia s procedure, Johnson and co-workers (89) have shown that the treatment of cyclopropyl bromide (301, 0H=Br) with anhydrous zinc bromide in ether gave smoothly the trans-homoallylic bromide 302. Only... 

Cyclopentyl bromide, b263 Cyclopentyl chloride, c79 Cyclopropyl bromide, b264 Cyclopropyl cyanide, c365... 

The addition of benzene to 2,3-dihydropyran was examined in the presence of cyclopropyl bromide [177] in an attempt to determine the nature of the excited state of benzene responsible for the formation of the ortho adduct [11,12], The absorption of the bromide at 254 nm was taken into account (90% of the radiation was absorbed by benzene) and a decrease of the rate of formation of 50% in the heavy-atom solvent was observed. Cyclopropyl bromide also quenched the fluorescence of benzene (kq = 3.82 X 10s L/mol 1 /s ). These data are interpreted as enhanced intersystem crossing of Si benzene and the necessary involvement of the Si state in formation of the ortho cycloadduct. 

Both Walborsky18 and Applequist16 showed that bromine-lithium exchange of a cyclopropyl bromide 352 - giving a highly configurationally stable cyclopropyllithium 353 - proceeds with reliable stereospecificity, presumably retention. 

Among transition metal complexes, the ubiquitous dicarbonylcyclopentadienyliron (Fp) complexes are the first, and perhaps the best, representatives to demonstrate the utility of metal-halogen exchange reactions in metallacyclopropane synthesis. Thus, reaction of the readily available sodium dicarbonylcyclopentadienyliron [Cp(CO)2Fe]Na (FpNa) with the parent cyclopropyl bromide " and derivatives " gave in moderate yields the corresponding cyclopropane-Fp complexes (equation 3). 

Spin-orbit coupling and delocalization are in competition in a molecule like cyclopropyl bromide for two reasons ... 

Cyclopropanecarboxylic acids can be converted into cyclopropyl bromides by the Hunsdiecker reaction " . The reaction of cyclopropyl bromides with K3Co(CN)5 produces non-stereospecifically the corresponding cyano derivatives " gem-Dibromocyclopro-panes also afford directly the cyano- and acetoxycyclopropanes upon treatments with K3Co(CN)5 and Cu(OAc)2, respectively " Trimethylsilylcyclopropane provides cyclopropyl ketones by the Friedel-Crafts reaction ". ... 

In more recent work, Leandri and coworkers have solvolysed a series of methylene dialkyl and methylene spiro cyclopropyl bromides as a method for preparing a-allenic tertiary alcohols. An example is shown below in the reaction of 1. Robertson and... 

The formation of cyclopropyl halide radical anion pairs as intermediates is also invoked in Sr I type substitution reactions by Rossi and Meijs . It seems that the photostimulated reaction of cyclopropyl bromides like 7-bromonorcarane (120) with Ph2P M to give 121 involves a radical chain, and halogen-containing radical anions as chain carrier. 

The reaction of hot tritium atoms with cyclopropyl bromide... 

---