Purpose: We evaluated the medium-term results obtained with the Tension-free Vaginal Tape operation. Methods: Over a 3-year period a total of 122 patients underwent a Tension-free Vaginal Tape operation for treatment of genuine stress incontinence. All patients were studied prospectively and underwent urodynamic studies before and after surgery. Postoperatively patients underwent urodynamic testing and subjective assessment at 6-12 and at 12 - 24 months. Results: The subjective and objective cure rates were 70% and 61%, respectively. Perioperative complications included bleeding, bladder perforation, voiding problems and de novo urgency. Preoperative urgency seemed to improve postoperatively. Conclusion: Overall there were few complications and the procedure was successful despite a mixed level of surgical experience.

Purpose: We evaluated the medium-term results obtained with the Tension-free Vaginal Tape operation.Methods: Over a 3-year period a total of 122 patients underwent a Tension-free Vaginal Tape operation for treatment of genuine stress incontinence. All patients were studied prospectively and underwent urodynamic studies before and after surgery. Postoperatively patients underwent urodynamic testing and subjective assessment at 6-12 and at 12-24 months.Results: The subjective and objective cure rates were 70% and 61%, respectively. Perioperative complications included bleeding, bladder perforation, voiding problems and de novo urgency. Preoperative urgency seemed to improve postoperatively.Conclusion: Overall there were few complications and the procedure was successful despite a mixed level of surgical experience.

Ab initio density functional theory (DFT) is used to analyze the vibrational unpolarized absorption and circular dichroism spectra (below 1500 cm(-1)) of seven derivatives of 6,8-dioxabicyclo[3.2.1]octane. Two are methyl derivatives, two are methyl-d(3) derivatives, and three are dimethyl derivatives. DFT calculations use hybrid functionals (B3LYP and B3PW91), the 6-31G* basis set, and, in predicting circular dichroism spectra, GIAO basis sets. The two functionals give qualitatively similar spectra. Comparison of predicted and experimental spectra permits assignment of the majority of the fundamentals of the seven molecules (excluding C-H stretching modes). Vibrational circular dichroism intensities are in good overall agreement with experiment, consistent with previously assigned absolute configurations. Spectra are also predicted using the Hartree-Fock/self-consistent field (HF/SCF) and MP2 methodologies. MP2 spectra are similar in accuracy to DFT spectra. HF/SCF spectra are of much lower accuracy and are in poor agreement with experiment.

Ab initio density functional theory (DFT) is used to predict the vibrational absorption and circular dichroism spectra of the insect pheromone 1,5-dimethyl-6,8-dioxabicyclo[3.2.1]octane: frontalin. Excellent agreement with experimental spectra is obtained for the structure in which the six-membered ring is in a chair conformation and the seven-membered ring is in a boat conformation. Vibrational circular dichroism (VCD) intensities, predicted on the basis of the previously determined absolute configuration, are in excellent agreement with experiment. We conclude that VCD spectroscopy, in combination with ab initio DFT, is now an efficient tool for determining the absolute configuration and/or conformation of chiral organic molecules, including pheromones.

A Bomem MB100-based vibrational circular dichroism (VCD) spectrometer suitable for chiroptical studies in the infrared region is described. The optical layout utilizes the spectrometer's external collimated beam. Standard VCD optics consisting of a KRS-5 polarizer and a ZnSe photoelastic modulator are mounted on an optical breadboard. A ZnSe meniscus lens focuses the beam on a small-area MCT detector. Several optical designs were examined to find the optimal positions of the optical elements. The experiments aimed to improve the energy throughput, minimize polarization artifacts, and increase signal-to-noise ratio to such an extent that single-enantiomer VCD spectra could be recorded routinely and dependably. Examples are presented illustrating the high-performance characteristics of the instrument.

The experimental VCD spectrum of (2R)-2-methylaziridine has been measured in the region 800–1500 cm−1. The ab initio implementation of the Vibronic Coupling Theory (VCT) of Nafie and Freedman, using the 6-31G*(0.3) basis set, in the common origin and distributed origin gauges and with uniformly and optimally scaled quantum mechanical force fields, is used to investigate the chiroptical properties. VCD spectra are computed for both cis and trans invertomers. The predicted VCD spectrum of 2-methylaziridine (the equilibrium mixture) is dominated by that of the trans diastereomer, not simply because of its greater abundance but because the rotatory strengths of many absorptions in the mid-IR are oppositely signed and of similar magnitude in the two invertomers which differ in absolute configuration at nitrogen. The VCD spectrum of 2-methylaziridine is compared in detail to that of 2-methyloxirane. In the region of the methyl group deformations and CH2 scissor, the theoretical (R)-2-methyloxirane VCD spectrum displays a much closer similarity to the cis-(2R)-2-methylaziridine than to the trans diastereomer.

The conformation and ring-puckering vibration of 2-methyloxetane have been studied using microwave spectroscopy and ab initio computations. The microwave spectra of the ground and first four excited states of the ring-puckering vibration have been observed in the frequency range 8-40 GHz and the rotational and quartic centrifugal distortion constants have been determined. Vibrational energy separations have been obtained from relative intensity measurements. The electric dipole moment (in D) of the ground vibrational state has been determined from Stark effect measurements as mu(a) = 0.0187 (5), mu(b) = 1.852(2), mu(c) = 0.08(3), and mu(t) = 1.854(3). The vibrational energy separations and the vibrational dependence of the rotational constants suggest that the ring-puckering vibration has an asymmetric single minimum potential function and also gave a revised assignment of the far infrared spectrum (J. Mol. Struct. 56 (1979) 157). A combined fit to the rotational constants, vibrational energy separations and far infrared vibrational frequencies has been used to determine a reduced potential for the ring puckering vibration. The partial derivatives of the rotational constants with respect to the reduced ring-puckering coordinate show that the equilibrium conformation has the methyl group in the equatorial position. Ab initio computations of the ring-puckering potential function have been made using 6-31G* orbitals and full geometry optimization. These computations also show the molecule to have an asymmetric single minimum potential function with an equatorial equilibrium conformation.

The vibrational circular dichroism (VCD) spectra of 2,3-dimethylaziridine 1 and 1,2-dimethylaziridine 2 were measured experimentally and interpreted with the help of ab initio Vibronic Coupling Theory (VCT) both in the common origin (CO) and distributed origin (DO) gauge. The absolute magnitudes of the VCD intensities by the VCT-CO method in the mid-IR range are closer to the experimental measurement. Both VCT-DO and VCT-CO methods, however, predict the same signs for almost all VCD bands. In general, both VCT-DO and VCT-CO methods predict VCD and IR spectra that are both in good agreement with the experimental spectra. The VCT method together with the 6-31G*(0.3) basis set can be employed with confidence in determining the absolute configuration of a chiral molecule. The theoretical and experimental VCD spectra of 1 and 2 were compared with the VCD spectra of the isostructural 2,3-dimethyloxirane and -thiirane. One of the Me rocking motions, in the wave number range 1050–1150 cm−1, was found to serve as a possible marker for the stereochemistry of the molecular skeleton. Two other modes were identified whose Cotton effects (CEs) are characteristic of the local asymmetry, and for which chirality rules were proposed. The first is a methyne vibration, ||CH, which is expected to have a (−) CE at a three-ring centre with (R) absolute configuration. The second is an umbrella motion of a methyl group, which is expected to have a (+) CE when attached to a three-ring centre with (R) absolute configuration.

The infrared absorption (vapor phase and solution) and Raman (liquid phase) spectra of bicyclo[3.2.1]octane, 8-oxabicyclo[3.2.1]octane, 6-oxabicyclo[3.2.1]octane, 6,8-dioxabicyclo[3.2.1]octane, and the 7,7-dideutero-substituted derivatives of the last two compounds are reported in the region 100–1500 cm−1 for the first time. The vibrational spectra are assigned almost completely with the guidance of ab initio 3-21G geometries and scaled force fields. A total of 14 force-field scale facors are transferred from smaller molecules, predicting the frequencies with an average error of 7.6 cm−1 (1.2%) for 196 assigned transitions. After optimizing the factors in an overlay refinement involving all six molecules, the frequencies are within 5.7 cm−1 (0.75%) of experiment. The ab initio absorption and Raman intensities are calculated with the 3-21G basis set and are demonstrated to be of such accuracy as to be useful for the spectral assignments. These intensities are calculated with uniformly and nonuniformly scaled force fields and compared to the experimental spectra. The intensities derived from the latter force fields are superior, meaning that nonuniform scaling is preferable at this level of theory for both vibrational frequencies and normal mode descriptions.

The structures of the cis and trans invertomers of 2-methylazirdine were optimized at the RHF/6-31G*(0.3) level of theory and the composition of the equilibrium mixture was determined to be trans/cis = 0.71:0.29, in good agreement with the experimental value, 0.66:0.35. The abinitio force field was scaled and a complete assignment of the vibrational spectra of the two conformers is presented. The IR spectrum of 2-methylazirdine was recorded in the vapor phase and in solution (cyclohexane and CCl4). The predicted IR spectrum of the equilibrium mixture agrees very well with the experimental spectrum. The 6-31G*(0.3) basis set is found to provide better geometries and more uniformly scalable force fields than the conventional 6-31G* basis set. Keywords: abinitio force fields, 2-methylaziridine.

The vibrational circular dichroism (VCD) and absorption spectra of 6,8-dioxabicyclo[3.2.1]octane between 800 and 1500 cm-1 are reported. Also presented here for the same region are the complete assignment of the vibrational bands, and the calculated absorption and VCD intensities, based on a previously obtained harmonic ab initio 3-21G force field which was scaled and refined to fit 195 observed frequencies of the title compound and five analogues. Relative absorption intensities are predicted successfully by the atomic polar tensor expression (APT), but not with the fixed partial charge model (FPC). APT also gives correct signs and reasonable absolute VCD intensities for most bands. FPC reproduces most VCD signs but underestimates the intensities considerably, particularly for modes that involve C-O stretching. The low FPC absorption and VCD intensities are substantially improved by adding one parameter, transferred from 2-methyloxetane, that introduces electronic charge flow along the C-O bonds. These model calculations suggest that significant contributions to the vibrational dipole moment derivatives are generated by electronic charge redistributions which can be adequately modeled by a transferred charge flow parameter.

The structure of 8-oxabicyclo[3.2.1]octane was calculated by abinitio means at the STO-3G level, and the structural data used to assign the microwave spectrum of the title compound in the range of 26.5 to 40 GHz fitting 144 lines up to J = 48 by adjusting the rotational and three centrifugal distortion constants in the Watson A reduction. Structural parameters were deduced from the rotational constants by allowing all bond lengths and angles to vary in a least-squares manner. These parameters were in good agreement with those calculated at the STO-3G and 3-21G levels. Of many satellite lines observed, only the most intense could be utilized for locating the two lowest fundamental vibrations, estimated to occur at 190 and 240 cm−1. The far-infrared spectrum is reported in the region of 80 to 300 cm−1, exhibiting only one distinct sequence of Q branches at 264 cm−1. On the basis of unsealed abinitio force fields at both levels of the theory the corresponding fundamentals are assigned, respectively, to a twisting (A″) and a bending (A′) of the cycloheptane ring. Keywords: 8-oxabicyclo[3.2.1]octane, microwave and far-infrared spectra, abinitio STO-3G and 3-21G geometries.

AbstractThe (1R) enantiomers (I)‐(III) and their (1S) antipodes are synthesized by standard synthetic methods and/or with baker's yeast.

The enantiomers of 6,8-dioxabicyclo[3.2.1]octane and the alkyl substituted derivatives, exo- and endo-7-methyl, exo- and endo-5,7-dimethyl, 7,7-dimethyl, and exo- and endo-7-ethyl-5-methyl (exo- and endo-brevicomin), were synthesized stereoselectively with known configuration by standard synthetic methods, or with baker's yeast, or both. The correlation between the absolute configuration of the bicyclic rings and the optical rotation was established by means of chiral complexation gas chromatography for two molecules for which this correlation was not known previously. In all cases, the (1R) enantiomer exhibits positive rotation. The absolute configurations were established for the yeast products which were always produced in high optical purity.

We report the measurement of the vibrational circular dichroism (VCD)1 and infrared absorption spectra of 6,8-dioxabicyclo[3.2.1]octane in the region 800 to 1500 cm-1. The observed bands are assigned with the guidance of a scaled ab initio 3-21G force field. VCD and absorption intensities were calculated using the fixed partial charge (FPC), charge flow (CF), and atomic polar tensor (APT) models.1 FPC yields correct signs but low absolute intensities for most of the observed VCD bands. Introduction of one CF parameter which allows charge flow along the C-0 bonds improves the FPC results remarkably and brings them close to the corresponding observed and APT intensities.