Herein, we describe the direct synthesis of pyrrolo­[1,2-α]­quinoxaline via oxidative coupling between methyl arene and 1-(2-aminophenyl) pyrroles. Oxidation of the benzylic carbon of the methyl arene was achieved by di-t-butyl peroxide in the presence of an iron catalyst, followed by conversion to an activated aldehyde in situ. Oxygen played a crucial role in the oxidation process to accelerate benzaldehyde formation. Subsequent Pictet–Spengler-type annulation completed the quinoxaline structure. The protocol tolerated various kinds of functional groups and provided 22 4-aryl pyrrolo­[1,2-α]­quinoxalines when various methyl arene derivatives were used. The developed method proceeded in air, and all catalysts, reagents, and solvents were easily accessible.

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Gaylussacin (1), a stilbene glucoside, has been isolated from Pentarhizidium orientale and is used in Korean folk medicine. Although it was first isolated in 1972, the synthesis of gaylussacin has never been reported. Herein, we report the first total synthesis of gaylussacin in six steps with an overall yield of 23.8%, as well as the synthesis of its derivatives. Structurally, gaylussacin contains a carboxylic acid and a glycoside along with a free phenol on the same benzene ring, making selective functionalization for the synthesis of 1 difficult. Heck cross-coupling was employed as a key step to introduce the stilbene moiety. Glycosylation followed by global deprotection provided natural product 1.

The objective of this study is to examine the effect of individual factors over human perception behavior and to determine the right set of parameters which effectively exploit the underlying network and system capacity while maximizing the QoS perceived by the user. For the comprehensive test, we examine three different types of video clips: news, drama and sport game. From each of the original video clip, we vary the encoding factors as follows: playback rate(384Kbits/sec and 1.5Mbits/sec), frame rate(5 frames/sec, 15 frames/sec, and 25 frames/sec) and spatial resolution(176x244 and 320x240). We performed extensive user experiment. We particularly focus on video streaming in mobile wireless environment where playback rate and screen size are relatively small. The analysis result reveals that out of three encoding factors, frame rate is the most influential factor. Spatial resolution does not make significant difference on QoS for three video categories. Playback rate results in noticeable difference in QoS. However, the analysis result suggests that the improvement on QoS obtained by quadrupling the playback rate (from 384Kbits/sec to 1.5 Mbits/sec) may not be justifiable particularly when the screen size is small.