Phosphorus trichloride in a basic medium is a convenient reagent for the direct C-phosphorylation

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Phosphorylation of 1-alkyl substituted imidazoles and benzimidazoles with P(III) halides in pyridine was shown to proceed at the 3-N atom of the heteroaryl ring and was followed by triethylamine-induced migration of the phosphorus group to the 2-C atom. Preparative methods were developed for the synthesis of a range of 2-phosphorylated derivatives of the indicated imidazoles. The latter were found to undergo alkylation either at P(III) or 3-N centers, depending on the alkylating agent.

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We propose a new way to structure the digital signal processing for reduced guard-interval (RGI) OFDM optical receivers. The idea is to digitally parallelize the processing over multiple parallel virtual sub-channels, occupying disjoint spectral sub-bands. This concept is well known in the optical or analog sub-carrier domains, but it turns out that it can also be performed efficiently in the digital domain. Here we apply critically sampled uniform analysis and synthesis DFT filter bank signal processing techniques in order to realize a novel hardware efficient variant of RGI OFDM, referred to as Multi-Sub-Band OFDM (MSB-OFDM), reducing by 10% receiver computational complexity, relative to a single-polarization version of the CD pre-equalizer. In addition to being more computationally efficient than a conventional RGI OFDM system, the signal flow architecture of our scheme is amenable to being more readily realized over multiple FPGAs, for experimental demonstrations or flexible prototyping.

Spectral processor based on arrayed waveguide grating and free-space manipulation is capable of arbitrary filtering at record metrics of 0.8GHz resolution over 200GHz span. Narrowband coherent drop-demultiplexing and controlled optical shaping is demonstrated in unison with digital sub-banding. IntroductionLinear optical signal processing operations can assist optical communications in performing myriads of operations such as wavelength multiplexing, wavelength selective switching (WSS), and complex spectral filtering for channel selection, dispersion compensation, and signal shaping. Adaptive filtering operations are particularly of interest, enabling tuning of the center wavelength, bandwidth, dispersion compensation level and signal formats. Performing these operations with a spatial light modulator (SLM) operating on spatially dispersed light has been demonstrated [1-3]. These and similar experiments are based on a WSS platform, using a dispersive free-space optics arrangement with a bulk diffraction grating and lenses, and replacing a micro-mirror SLM [4] with a liquid-crystal on silicon (LCoS) SLM [5]. The performance of these instruments is set by the spectral resolution of the dispersing arrangement (typically 8-10GHz) and the pixel pitch determining spectral addressability (few GHz). Improved performance metrics can be obtained by replacing the bulk diffraction grating with an arrayed waveguide grating (AWG) [6,7], which is designed to provide higher dispersion values over a finite free spectral range (FSR). In this work we demonstrate ×10 improvement in the photonic spectral processor performance,

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Preparative methods o f synthesis of 1and 3-phosphino-indolizines by interaction between 2-substituted indolizines with phosphorus(III) halogenides in the presence of bases have been developed. I t was found that originally this reaction results in the formationof 1 -phosphino-indolizines which then undergo izommiation into 3-phosphino isomevs. One, two, or three indolizine substituents can be consecutively attached to the phosphorus atom. New methods of syntheses of 1,3-diphosphino-indolizines have been developed. 0 1993 VCH Publishers, Inc.