Search

A successful Cu-catalyzed addition of both Cl and SO

The first example of PdII -catalyzed enantioselective C-H olefination with non-chiral or racemic sulfoxides as directing groups was developed. A variety of chiral diaryl sulfoxides were synthesized with high enantioselectivity (up to 99 %) through both desymmetrization and parallel kinetic resolution (PKR). This is the first report of PdII -catalyzed enantioselective C(sp2 )-H functionalization through PKR, and it represents a novel strategy to construct sulfur chiral centers.

In order to improve the accuracy of derivative conversion of gravity anomalies and reflect anomaly characteristics of geologic bodies effectively, we propose a new method of calculating anomaly derivatives using cosine transform. Two theorems are put forward and proved and the common expression of the cosine transform spectrum of the gravity potential field and formula to calculate derivatives of gravity anomalies are deduced. So a theory of cosine-transform-spectra of the potential-field is established. In model experiments, we find that the deviation of the first derivative calculated by Fourier transform is very large comparing with the theoretical derivative, but the fitting effect of the anomaly derivative calculated by cosine transform is excellent. The calculation accuracy of data is all very high except that errors of several data on the boundary are large because of the residual Gibbus effect induced by finite truncation of gravity anomalies. Errors are –0.09%~5%.

We propose a method of calculating normalized full gradients of gravity anomalies using Hilbert transform to improve the resolution of geophysical data processing. We prove the feasibility of the method in theory and give the calculating way that can be performed on computer. We calculate the GH field values of a model using methods of Fourier series, Fourier transform and Hilbert transform, respectively and discuss the resolution for oil-bearing structures with these methods. The methods of Fourier series and Fourier transform cannot distinguish the anomaly of low-density body but the method of Hilbert transform can fairly do when the thickness of the oil storage part (low-density body) of 3-D sphere-coronal (approximate model of 3-D oil storage anticline) is lower than one tenth of that of the sphere-coronal. It indicates that the resolution power of discerning anomaly in computing GH field value using Hilbert transform is much better than other two methods.