The fluorination of Butane over cobalt trifluoride

The fluorination of butane over cobalt trifluoride has given a complex mixture of partially fluorinated compounds: 51 of these have been identified, comprising over 99% of the products. Most were polyfluorobutanes but 1-2% were polyfluoro-2-methylpropanes. The reaction has no synthetic utility. There was some selectivity in the fluorination: secondary C-H was converted into C-F more easily then primary, and the ease of replacement of a particular H was reduced by geminal and vicinal fluorines. A computer of the fluorination was only partially successful, perhaps because the fluorination proceeded in part by simple F for H replacement and in part via alkenes: the model only allowed for the former.     

The fluorination of 2-methylpropane over cobalt trifluoride

2-Methylpropane has been fluorinated over cobalt trifluoride at 140-200°C to give a mixture of at least 30 components, of which 22 have been identified with some certainty and five, more tentatively; this represents well over 95% of the reaction mixture. About 95% of the identified products were polyfluoro(2-methylpropanes); the rest were polyfluorobutanes. The fluorination was not completely random; there was a clear preference (by some 10 times greater than chance) for compounds in which the tertiary hydrogen had been replaced by fluorine. A scheme for the fluorination pathway is proposed. Attempts to dehydrofluorinate 1 ,3 -pentafluoro-2-fluoromethylpropane failed.     

The fluorination of benzene over manganese trifluoride

Flourination of benzene, in the vapour phase, over manganic fluoride at 300° has given undecafluorocylohexane (3.5%); 1H-, 3H- and 4H-nonafluorocyclohexene (3.3, 0.2 and 1.6%, respectively); 1H/2H- and 1H/4H-decafluorocyclohexane (1.1 and 6.2%, respectively); 1H,4H-hexafluorocyclohexa-1:4-diene (4.0%); 1H,2H- and 1H,4H-octafluorocyclohexene (0.04 and 15.8%, respectively); floruo- (3.9%), p-difluoro- and 1,2,4-trifluoro-benzene; 1H4H/2H, 1H/2H,4H- and 1H,2H/4H-nonafluorocyclohexane; and 1H,3H/4H-, 1H,4H/5H- and 1H, 2H,4H- (8.0%) heptafluorocyclohexene.     

The fluorination of ethane and ethene over potassium tetrafluorocobaltate(III) and cobalt trifluoride

Fluorination of ethane and ethene with KCoF₄ and CoF₃ over a range of temperatures gave, in all cases, mixtures of polyfluoroethanes, C₂H_6-nF_n n = 1–6, with very little CC bond cleavage. Apart from an initial easy saturation of ethene to CH₂FCH₂F, both substrates had a similar reactivity. Hydrogen appeared to be replaced by fluorine almost randomly in all fluorinations. CH₂FCH₂F is a stable compound, contrary to literature reports.     

Unusual rearrangement of spiro β-lactams to 1,4-diazabicyclo[4,4,0]decanes and 1,4-diazabicyclo[4,3,0]nonanes. Synthesis of conformationally restricted σ-receptor ligands

Synthesis of 1,4-diazabicyclo[4,4,0]decanes and 1,4-diazabicyclo[4,3,0]nonanes was achieved by using 4-formyl spiro β-lactams as easily available starting materials. Furthermore, the application of this protocol to the preparation of conformationally restricted σ-receptor ligands was also performed. Theoretical calculations were carried out on a model reaction, in order to give some understanding of the reaction mechanism.     

丁基苯的三氟化钴气相氟化

以元素氟、高价金属氟化物和电化氟化链状有机化合物往往得到许多副产物,而主要产物产率较低,通常认为氟化时伴随有链的降解,重排和聚合等副反应.以三氟化钴进行氟化只有少量环化产物生成.近年来由于分离技术的提高,对复杂的氟化产物进行分离鉴定、探讨氟化机理从而提高反应得率,使氟化反应进一步得到开发利用.我们将丁基苯以三氟化钻进     

Polyfluorobicyclo[2,2,2]octanes. Part III. Syntheses and reactions of new mono- di- and trihydrides and derived compounds

Fluorobicyclo[2,2,2]octanes as follows were made by fluorination with cobaltic fluoride :- 1H- and 2H- tridecafluoro- ; 1H,2H-, 1H,3H-, 2H,2H-, 2H,3H-, and 1H,4H- dodecafluoro-; 1H,2H,3H-, 1H,2H,4H-, and 1H,3H,3H- undecafluoro-; 2H,2H,3H,3H- decafluoro-. These afforded, by the appropriate dehydrofluorinations, dodecafluoro-; 1H- and 2H- undecafluoro-; 1H,2H-, 1H,3H-, and 1H,4H- decafluoro- bicyclo[2,2,2]oct-2-ene. Self-consistent nmr data confirmed all structures. 1H-Trideca- and 1H,4H-dodeca- fluorobicyclo[2,2,2]octanes possess acidic bridgehead hydrogens, which are reactive under basic conditions, and may be replaced by various functional groups. 1-Lithiotridecafluorobicyclo[2,2,2]octane, a remarkably stable perfluoroalkyl lithium derivative, survived many hours in refluxing ether, but slowly decomposed to 1- substituted undecafluorobicyclo[2,2,2]oct- 2-enes, via a transient intermediate, a bridgehead ‘olefin’ ‘violating’ Bredt's rule.     

Synthesis of 1,6,7-trioxa-spiro[4.5]decanes

As potential antimalarial agents, four novel spiro-peroxides were designed and synthesized with the peroxy bond introduced employing the Kobayashi’s methodology (with modifications). The results showed that by using cyclic hemiketal as substrates the incorporation of the hydroperoxyl group could be achieved in high yields without recourse to the expensive Sc(OTf)₃ catalyst.     

Spirans XXI. Synthesis of silaazaspiro[4.5]decanes and silaazaspiro[5.5]undecanes

N-(2-Dimethylaminopropyl)-8,8-dimethyl-8-sila-2-azaspiro[4.5]decane ( 1 ) and N-(3-dimethyl-aminopropyl)-9,9-dimethyl-9-sila-3-azaspiro[5.5]undecane ( 2 ) have been synthesized from 4,4-dimethyl-4-silacyclohexanone ( 5 ). Biological evaluation of 1 and 2 indicated cytotoxic action against human cancer cells grown in tissue culture.     

Polyfluorobicyclo[2, 2, 2]octanes. Part II. Syntheses of polyfluorobicyclo[2, 2, 2]oct-2-enes from polyfluoro-cyclohexa-1,3-dienes

Diels-Alder reactions between ethylene and octa-, 1$\text{H}$-hepta-, and 1H, 4H-hexa-fluorocyclohexa-1,3-diene gave, respectively, 1,2,3,4,5,5,6,6-octa-, 1,2,3,5,5,6,6-hepta-, and 2,3,5,5,6,6-hexa-fluorobicyclo[2, 2, 2]oct-2-ene, each characterised by oxidation to the corresponding polyfluorocyclohexane-1,4-dicarboxylic acid.     

Spirans XX. Synthesis of 8,8-dialkylazaspiro[4.5] decanes and 9,9-dialkylazaspiro[5.5]undecanes

N-(2-Dimethylaminopropyl)-8,8-dimethyl-2-azaspiro[4.5]decane ( 1 ), N-(2-dimethylaminopropyl)-8,8-diethyl-2-azaspiro[4.5]decane ( 2 ), N-(3-dimethylaminopropyl)-9,9-dimethyl-3-azaspiro[5.5]undecane ( 3 ), and N-(3-dimethylaminopropyl)-9,9-diethyl-3-azaspiro[5.5]undecane ( 4 ) have been synthesized from 4,4-dimethylcyclohexanone ( 5 ) and 4,4-diethylcyclohexanone ( 6 ). Biological evaluation of these amines showed significant inhibition of cancer cell growth in human cancer cells grown in tissue culture.     

Tautomer chemistry of thiazolidines. 1-Thia-4-azaspiro[4,5] decanes

The thiazolidine, 1-thia-4-azaspiro[4,5] decane (Ia), which is derived from cyclohexanone and 2-aminoethanethiol (X), forms a thiazolidone (VIII) with mercaptoacetic acid more slowly and in lower yield than with 2-phenylthiazolidine, a case reported previously. A thiazolidine which is related to a non-conjugate chain tautomer such as Ic, might be expected to behave in this way. Alkylation, as another possible example of tautomer chemistry, was studied, and N-, S-, and C-alkylation were all observed under varying circumstances. Thus, thiazolidine la undergoes alkylation with methyl iodide in ethanol to form the N-methylthiazolidine (IIa), and in sodium-liquid ammonia to give the S-methyl derivative (III). In the latter case, alkylation occurs with reductive cleavage. Although no trace of other tautomer derivatives (IV, V) was to be found in the methyl iodide alkylation, I with acrylonitrile did in fact give C-alkylation. An analytically pure mixture of tautomers was obtained, from which 2-oxocyclohexanepropionitrile (VI) was isolated on hydrolysis. In a manner similar to the formation of III, IIa was S-alkylated by treatment with sodium-liquid ammonia followed by benzyl chloride to give a saturated product (XVII). Although such a process might be identified with a chain tautomer (IIb), the evidence is to the contrary, since the intermediate (XIV), which might be involved in such a process, fails to undergo a similar reduction with sodium-liquid ammonia. A greatly improved procedure for the preparation of thiazolidine (XI, 86% yield) is also reported.     

Spiro[4.5]decanes by photoannelation. Total synthesis of (−)-acorenone

An efficient synthesis of the optically active spiro[4.5]decane sesquiterpene acorenone is described. The key carbon-carbon bonds are formed by a (2+2) photochemical cycloaddition between 2,2-dimethyl-3(2H)-furanone and an alkene derived from limonene.     

Lewis acid-mediated generation of bicyclo[5.3.0]decanes and bicyclo[4.3.0]nonanes

[reactions: see text] Fragmentation of the cyclobutane-containing adducts generated from intramolecular cycloadditions of cyclobutadiene with olefins provides rapid entry into bicyclo[5.3.0]decane and bicyclo[4.3.0]nonane ring systems. Whereas earlier studies featured thermal methods to achieve the desired rearrangements, a mild, Lewis acid-mediated fragmentation has been identified for substrates with appropriate functionality adjacent to the strained ring system. The substrate scope and stereochemical outcome of the acid-mediated fragmentation are complementary to the thermal ring expansions, particularly in the case of the bicyclo[5.3.0]decanes.     

Synthesis of 1-substituted 2,9,10-trioxatricyclo[4.3.1.0]decanes

A series of 1-alkyl- and 1-alkenyl-2,9,10-trioxatricyclo[4.3.1.0^3,8]decanes, models for the core orthoester structural moiety of resiniferatoxin and synaptolepis factors, was prepared by a transetherification reaction of (±)-all-cis-cyclohexane-1,2,4-triol and trimethyl orthocarboxylates. The synthesis of the starting trimethyl orthocarboxylates is also given in detail.     

Synthesis of 2H-pyrano[2,3-b]quinolines. Part I

3,4-Dihydro-2H-pyrano[2,3-b]quinolines 5a-e and 2H-pyrano[2,3- b ]quinolines 10a-c were synthesised starting from the appropriate ω-chloro-n-valeroylanilides 2a-e . Compounds 10a-c were transformed to analogs of the novel antihypertensive agent Cromakalim ( 1 ).     

Directed 2-azonia-[3,3]-sigmatropic rearrangements. a convenient preparation of substituted 1-azaspiro[4,5]decanes

3-Acetylpyrrolidines are prepared from 5-methyl-5-vinyloxazolidines in a reaction which involves a directed 2-azonia-[3,3]-sigmatropic rearrangement.