Cyclopentanes fluoro

Epoxidation of substituted spiro[cyclopentane-l,9 -fluorene]-2-enes 68 with a peroxidic reagent was studied [98], The spiro olefins react with m-chloroperbenzoic acid (mCPBA) in chloroform at 3 °C to give a mixture of the epoxides. In all cases (2-nitro (68b), 4-nitro (68c), 2-fluoro (68d) and 2-methoxyl (68e) groups), the iyn-epoxides, i.e., the syn addition of the peroxidic reagent with respect to the substituent, is favored. For example, for 6 nsyn anti = 63 31 for 68c syn anti = 65 35. Thus, a similar bias is observed in both the reduction of the carbonyl derivatives of 30 and the epoxidation of the derivatives of 68. 

Xenon difluoride reacted with various carboxylic acids, and the type of transformation depends on the structure of the organic molecules35-39. The reaction with primary carboxylic acids involves free-radical intermediates. 6-Hexenoic acid was used as a free-radical clock device in which a A abs of 1.1 x 106 M-1s-1 at 25 °C was determined, while the alkyl radical was also spin-trapped to give an ESR signal37. The primary free radical was trapped by internal cyclization, and (fluoromethyl) cyclopentane in 25% yield was formed, while 6-fluoro-l-hexene could be formed from a radical or ionic intermediate, but 1-fluo-rocycloclohexane was not observed as a product (Scheme 42). 

An intermediate prepared from isopropylidene-D-glyceraldehyde via a Claisen rearrangement and previously used for the synthesis of some branched-chain fluorinated nucleosides (Vol. 32, p. 272-273), has now been used to make a fluorinated cyclopentane unit, to which was linked 6-chloropurine, thus leading to carbocyclic 2, 3 -dideoxy-4 -fluoro-L-adenosine (161). The same synthetic sequence could be modified to generate, via a metathesis step, an enantiomeric cyclopentane unit, and hence the enantiomer of 161, and equivalent structures with the other nucleobases. ... 

Mean while, to a mixture of 190.0 g 2-bromo-4-fluoro-aniline (1 mol) and 0.6 L water at room temperature was added 3 mol concentrated HCI the resulting thick white slurry was cooled to 0°C. A solution of 1 mol NaN02 in 0.7 L water was added slowly over 25 min, at such a rate as not to exceed an internal temperature of 10°C, and the reaction was aged for 30 min before filtration to remove any insoluble precipitate. This filtered diazonium solution was added to the prepared sodium carboxylate solution at 0°C dropwise over a period of 40 min (Note If added to the solution of sodium carboxylate, then it was not necessary to acidify the sodium carboxylate with concentrated HCI.) The resulting thick yellow slurry was stirred to room temperature, filtered, and dried under a stream of nitrogen to give 270.9 g (4 1 ratio) l-( /Z)-cyclopentane-l,2-dione (2-bromo-4-fluorophenyl)hydrazone as a yellow solid, in a yield of 95%, m.p. 182-187°C. 

C15H13FO2, DL-2-(2-Fluoro-4-biphenyl)propionic acid, 41B, 20 Ci5Hi3N08, Dimethyl 4-(2-carboxyvinyl)-a-cyanocinnamate, 44B, 14 C15H30O1, 2-Monolaurin, 30B, 11 CieHmOi, Diphenyl succinate, 45B, 14 CieHisO, Diethyl p-phenylenediacrylate, 44B, 14 Cl6H22CIN, 3 -(/3-Methylaminoethyl)Spiro(cyclopentane-1,1 -indene) hydrochloride, 42B, 24... 

Carbocyclic Analogues - Carbocyclic 2 -fluoro-ara-guanosine (25) has been synthesized by two routes from cyclopentane precursors, with enzymic resolution the (+)-isomer showed extremely high levels of activity against herpes simplex viruses without affecting uninfected... 

Fluoro-olefins may react in three ways with complexes of nickel, palladium, and platinum (i) halogen (or pseudo-halogen) transfer to the metal may occur with formation of a vinyl derivative (ii) the olefin monoadduct may be stable [these are probably best regarded as metal(n) complexes] or (iii) insertion of a further mole of olefin may occur, a metallo-cyclopentane being formed. The possible reaction pathway is affected by quite subtle changes in the olefin and in the metal ligands. 

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