2- Bicyclo pentyl

Bridgeheads. The Sn2 mechanism is impossible at most bridgehead compounds (p. 392). Nucleophilic attack in [l.l.l]propellane has been reported, however. In general, a relatively large ring is required for an SnI reaction to take place (p. 396). " The SnI reactions have been claimed to occur for l-iodobicyclo[l.l.l]pentane via the bicyclo[l.l.l]pentyl cation, but this has been disputed and the bicyclo[1.1.0]butyl carbinyl cation was... 

Sodium, with l-bromo-3-chloro-cyclobutane to give bicyclo [l.l.O]butane, 51, 55 Sodium amalgam, 50, 50, 51 Sodium amide, with 2,4-pentane-dione and diphenyliodonium chloride to give l-phenyl-2, 4-pentanedione, 51, 128 Sodium azide, 50, 107 with mixed carboxylic-carbonic anhydrides, 51, 49 Sodium borohydride, reduction of erythro-3-methanesulfony-loxy-2-butyl cyclobutanecar-boxylate, 51, 12 reduction of 2-(1-phenylcyclo-pentyl)-4,4,6-trimethyl-5,6-dihydro-1,3(4H)-oxazine to 2-(1-phenylcyclopentyl)-4,4, 6-trimethyltetrahydro-l,3-oxazine, 51, 25 Sodium cyanoborohydride, used... 

O-CO-CH3I 1 - CH- -CH3-0-C0-CHt O Toluol 2,5 5-Nitro-6-( 1,2,3,4,5-penta-acetoxy-pentyl) -bicyclo [2.2.1 hept-2-en -100 3... 

Wiberg and McMurdie have prepared bicyclo[1.1.0]butyl-l-carbinyl cation 13 by the ionization of bicyclo[l.l.l]pentyl-l-bromide with SbFother derivatives give products derived from the intermediacy of 3-methylenecyclobutyl cation 14, rather than the bicyclobutylcarbinyl cation (equation 22). In nucleophilic solvents, solvent... 

C2). It is interesting that solvolysis of the bicyclo[l. 1. l]pentyl-l-bromide or other derivatives give products derived from the intermediacy of 3-methylenecyclobutyl cation 14, rather than the bicyclobutylcarbinyl cation (equation 22). In nucleophilic solvents, solvent... 

Methoxycarbonyl-pentyl)-E16c, 843 (NH - N-R) 9-Aza-bicyclo[4.2.1]nonan 2-Ethenyl-... 

An investigation of the hydrolysis rates and products of derivatives of the parent 2-bicyclo[2.1.0]pentyl system was first reported by Wiberg and coworkers in 1968 in a... 

SCHEME 7. The relative rates and products of hydrolysis of the endo- and exo-2-bicyclo[2.1.0]pentyl 3,5-dinitrobenzoates in 80% aqueous acetone ... 

Another system which is not usually considered as a 2-bicyclo[2.1.0]pentyl system but in reality is a 3,5-ethano bridged endo derivative is the tricyclo[2.2.1.0 ]hept-2-yl p-nitrobenzoate (55) shown below " . This is related to the anti-7-norbornenyl system by... 

The slightly lower rate of the endo-bcnzo isomer 56 must be due to an electron-withdrawing inductive effect, and the endo-exo rate difference due to the same reasons as for the parent 2-bicyclo[2.1.0]pentyl system ... 

The same products were obtained in the solvolysis of 4-chlorospirohexane 1-methyl-bicyclo [2.1.0] pentyl p-nitrobenzoate, 1-cyclobutenylethyl tosylate and l-methyl-bicyclo[ 1.1.1] pentyl dinitrobenzoate, suggesting that the bicyclo [2.1.0]pentane-1-methyl cation is the common intermediate. 

Oxo-l-pentyl- 323 Bicyclo 3.1.1]heptane 2-Acetyl-3,6,6-trimethyl- 2490 Bicy clo 4.1.0]hept-2-ene 7-Butyl-7-methoxy- 768... 

The study of substituent effects on the stability of substituted benzyl cations is important as a source of thermodynamic information as well as a means to provide a conceptual link between the stabilities of a number of important carbocations. Mishima s study, in particular, shows that the stabilities in terms of standard Gibbs energy for 4-methoxy- and 4-nitro-substituted benzyl cations differ by some 24.9 kcal mol The former has a stability comparable to that of bicyclo[3.3.3]undecyl (manxyl) cation, while the latter is comparable to the c-pentyl cation. We present these two extreme cases in Table 4. The relative stabilities of other substituted benzyl cations are given in Refs. 50 and 51. 

---