17530-61-9Relevant articles and documents
1-(1-polycycloalkyl)methylidene>+ to 2-(1-homopolycycloalkene)>+ Rearrangement. Carbon Migration in Iron(II) Alkylidenes. A New Route to Stabilized Bridgehead Olefins
Bly, Robert S.,Bly, Ruta K.,Hossain, Mahmun M.,Lebioda, Lukasz,Raja Muthukrishna
, p. 7723 - 7730 (1988)
Acyls (CO)2(η5-C5H5)FeCOR (18: a, R = 1-bicyclooctyl; b, R = 1-bicyclooctyl; c, R = 1-adamantyl) are synthesized from the corresponding 1-polycycloalkanecarbonyl chlorides and (CO)2(η5-C5H5)FeK.The acyls, 18, react with (C2H5)3O+BF4- or with CH3OSO2CF3 to form 1-alkoxy-1-polycycloalkylmethylidene salts, (CO)2(η5-C5H5)Fe=C(OC2H5)R>+BF4- (19: a, R = 1-bicyclooctyl) or 5-C5H5)Fe=C(OCH3)R>+CF3SO3- (22: a, R = 1-bicyclooctyl; b, R = 1-bicyclooctyl; c, R = 1-adamantyl), which react with LiHB(C2H5)3/CH2Cl2 or NaBH4/CH3OH/CH3ONa to form an ca. 50:50 mixture of the racemic, diastereomeric alkoxyalkyls, (CO)2(η5-C5H5)FeCH(OR')R (20a and 21a, R' = C2H5, R = 1-bicyclooctyl or 23a and 24a, R' = CH3, R = 1-bicyclooctyl) or the racemic 23 (b, R' = CH3, R = 1-bicyclooctyl; c, R' = CH3, R = 1-adamantyl).The alkoxyalkyls 20a and 21a, 23a and 24a, and 23b and 23c react with either HBF4/(C2H5)2O/CH2Cl2 or (CH3)3SiOSO2CF3/CH2Cl2 to form alkylmethylidene salts, (CO)2(η5-C5H5)Fe=CHR>+ (25+: a, R = 1-bicyclooctyl; b, R = 1-bicyclooctyl; c, R = 1-adamantyl), of BF4- or CF3SO3-, respectively, which are unstable and rearrange at -78 deg C or below to the corresponding 5-C5H5)Fe(η2-1-homopolycycloalkene)>+, 26+ (η2-1-bicyclononene), 29+ and 30+ (re- and si-η2-1-bicyclononene, respectively), or 31+ (η2-3-homoadamantene) BF4- or CF3SO3- salts.The products are identified by 1H and 13C NMR and, in the cases of 26+BF4-, 29+CF3SO3-, and 30+CF3SO3-, by single-crystal X-ray diffraction.Complex 26+BF4- reacts with (CH3)3NO to form (Z)-1-bicyclononene, 3.Alkylidene 25+ reacts with LiBH(C2H5)3/CH2Cl2 at -78 deg C to form (CO)2(η5-C5H5)Fe(η1-bicyclooctylcarbinyl), 28, prepared independently by treatment of 18a with BH3/THF.These 1-polycyclomethylidene to 1-homopolycycloalkene rearrangements and the rearrangement of 5-C5H5)Fe=CHC(CH3)3>+ (32+) have been followed and the first-order rate consants determined by variable-temperature 1H and/or 13C NMR: 25a+, k1(-95 deg C) = 2.3 x 10-6 s-1; 25b+, k1(-95 deg C) = 9.0 x 10-6 s-1; 25c+, k1(-95 deg C) = 9.4 x 10-10 s-1; 32+, k1(-95 deg C) = 4 x 10-3 s-1.The log k1's, statistically corrected for the number of conformations that can rearrange to the observed produdct, correlate (r2 = 0.924) with the differences in estimated strain energies of the 1-alkyl substituent and the rearranged (bridgehead) cation unstabilized by the adjacent iron(II) moiety.These rearrangements consitute the first reported examples of a β- to α-carbon shift in a transition-metal alkylidene.
Influence of strain on chemical reactivity. Relative reactivity of torsionally distorted double bonds in MCPBA epoxidations
Shea, Kenneth J.,Kim, Jang-Seob
, p. 3044 - 3051 (2007/10/02)
The second-order reaction rates were measured for the MCPBA epoxidation in CH2Cl2 for a series of cyclic olefins including bridgehead olefms and trans-cycloalkenes. As expected, strained bridgehead alkenes and trans-cycloalkenes showed faster reaction rates than nonstrained cis-cycloalkenes. The MM-2 steric energies of alkenes, alkanes, and their corresponding epoxides were calculated to evaluate the strain energy released in each reaction (ΔSE). Plots of log krel vs olefin strain did not show a good correlation. However, the plot of log krel vs ΔSE (which is defined as the steric energy difference between olefin and the corresponding epoxide) showed a good correlation for each set of di- and trisubstituted olefins. This result suggests that ΔSE directly reflects strain energy relief in the transition state. From the slope for the plot log krel vs ΔSE, it was thought that approximately 42% of strain (ΔSE) was released in the transition state for the MCPBA epoxidation. Also, trialkyl-subtituted alkenes were found to be about 50 times more reactive than dialkyl-substituted alkenes in cases where the strain energy relief (ΔSE) is the same. The reaction rate is also plotted versus ionization potential of the olefin, assuming that the major orbital interaction lies between the LUMO of the peracid and the HOMO of the olefin. Although, in some cases, a rough correlation of the reaction rate with the ionization potential of the olefin exists, the frontier orbital interaction is not viewed as the dominant factor since conjugated alkenes, which have higher HOMO energies than simple olefins, are not more reactive in MCPBA epoxidation.
SYNTHESES OF BICYCLIC 1,2-DIOLS VIA THE RING-EXPANSION OF BRIDGEHEAD ALDEHYDES OF BICYCLOOCTANE AND BICYCLONONANES WITH BENZOYL TRIFLATE
Takeuchi, Ken'Ichi,Ikai, Keizo,Yoshida, Masayasu,Tsugeno, Akio
, p. 5681 - 5694 (2007/10/02)
Bridgehead aldehydes of bicyclooctane (11a), bicyclononane (12a), and bicyclononane (13a) have been subjected to acylative ring-expansion by using benzoyl trifluoromethanesulfonate (triflate) to give mixtures of two or three bicyclic
