Total Synthesis of Symbioramide: a Flexible Approach for the Efficient Preparation of Structural Isomers

A concise, enantioselective total synthesis of symbioramide, starting from simple achiral compounds and racemic α‐amino‐β‐keto ester derivatives is reported. This highly flexible strategy allowed the efficient preparation of seven structural isomers of the natural product as well. The synthesis relies on a convergent route that involves the efficient stereoselective reduction of a α‐keto‐β‐yne ester, and the dynamic kinetic resolution of an α‐amino‐β‐keto ester through ruthenium‐mediated asymmetric hydrogenation.     

Practical Solvent‐Free Ruthenium Trichloride‐Mediated Benzannulation Approach to Fused Functionalized Arenes

The solvent‐ and ligand‐free [2+2+2] ruthenium‐promoted cycloaddition of α,ω‐diynes and alkynes provides a facile and efficient strategy for the synthesis of substituted benzene‐derived systems. The search for the optimal reaction conditions revealed the unprecedented catalytic activity of ruthenium trichloride for benzannulation reactions and this atom‐economical process allowed the synthesis of fused arenes including dihydrobenzofurans, isoindolines, indanes in good to high yields. This practical protocol also gave rise to the preparation of pentasubstituted aromatic derivatives and was applied to the one‐gram scale synthesis of a functionalized heterocycle.

     

Wavelength conversion by optimized monolithic integrated Mach-Zehnder interferometer

Semiconductor optical amplifiers have been monolithic integrated in a passive symmetric Mach-Zehnder interferometer to form a compact polarization insensitive all-optical wavelength converter operating at up to 10 Gb/s. A simple method for reducing the impact of input power variations is proposed that increases the input power dynamic range from 4-8 dB.     

Active lossless monolithic one-by-four splitters/combiners usingoptical gates on InP

Active one-by-four splitters/combiners were fabricated on InP from the monolithic integration of waveguides and amplifiers. The device exhibited propagation loss below 1.5 dB·cm^-1, S-bend loss of 0.2 dB per bend, a 3-dB optical bandwidth of 23 nm, a mean optical crosstalk and extinction ratio of, respectively, 37 dB and 42 dB. On all paths, at least 0 dB insertion loss (fiber to-fiber gain up to 2.8 dB) as well as a low polarization sensitivity (below 1.0 dB) were demonstrated. This device can be used as the basic building block of bit-rate transparent switches for optical routing and broadcasting     

Convenient General Asymmetric Synthesis of Roche Ester Derivatives through Catalytic Asymmetric Hydrogenation: Steric and Electronic Effects of Ligands

An efficient and concise asymmetric hydrogenation of acrylate esters promoted by the cationic ruthenium monohydride complex [Ru(H)(η⁶‐cot)SYNPHOS]⁺BF₄⁻ is reported. A full investigation of the effects of catalyst precursors, solvents, temperature, hydrogen pressure, substrates as well as steric and electronic properties of ligands was carried out. The corresponding valuable Roche ester derivatives were obtained in good to excellent isolated yields and high enantioselectivities under mild conditions. The robustness and practicability of this highly enantioselective hydrogenation was demonstrated by the synthesis of the 3‐hydroxy‐2‐methylpropanoic acid tert‐butyl ester on a multigram scale, resulting in excellent yield and ee up to 94%.     

An all-optical wavelength-converter with semiconductor opticalamplifiers monolithically integrated in an asymmetric passiveMach-Zehnder interferometer

An all-optical wavelength-converter based on monolithic integration of a Mach-Zehnder interferometer and integrated semiconductor optical amplifiers was demonstrated. This device exhibited high stability, penalty-free conversion at 5 Gbit/s (at a BER of 10⁹), no-excess penalty after a transmission over 60 km on standard fiber, and low signal-polarization dependency. The device operated in a 26-nm-wide optical window     

Highly Enantioselective Synthesis of 3‐Hydroxy‐2‐methylpropanoic Acid Esters through Ruthenium‐SYNPHOS®‐Catalyzed Hydrogenation: Useful Building Blocks for the Synthetic Community

Both enantiomers of 3‐hydroxy‐2‐methylpropanoic acid tert‐butyl ester were prepared with high enantioselectivity (up to 94 %) through a ruthenium‐SYNPHOS®‐promoted asymmetric hydrogenation reaction using an atom‐economic transformation from simple and inexpensive precursors.     

General Enantioselective Synthesis of Butyrolactone Natural Products via Ruthenium‐SYNPHOS®‐Catalyzed Hydrogenation Reactions

Enantioselective syntheses of several paraconic acids have been achieved using catalyzed asymmetric hydrogenation of β‐keto esters with SYNPHOS^® as a ligand. This strategy allowed the short synthesis of biologically active (−)‐methylenolactocin 1 , (−)‐protolichesterinic acid 2 , (−)‐phaseolinic acid 3 and (+)‐roccellaric acid 4 .     

High speed, high capacity ATM optical switches for futuretelecommunication transport networks

This paper describes the work carried out in the RACE Project R2039 ATMOS (asynchronous transfer mode optical switching). The project is briefly illustrated, together with its main goal: to develop and assess concepts and technology suitable for optical fast packet switching. The project's technical approach consisted in the exploitation of the space and wavelength domains for fast routing and buffering: The major achievements are then reported. Four different switch architecture concepts have been proposed, investigated and developed, all based on a high speed optical routing matrix electrically controlled at lower speed. The basic optical key components and subsystems (wavelength converters, space switches and optical buffers) are described in detail, with the outstanding results obtained and the corresponding projected performance. In particular, system demonstration of wavelength conversion at 10 and 20 Gb/s has been realized, to show the usefulness of the ATMOS technology both to implement optimized high performance optical packet-switching fabrics as well as transparent optical circuit-routing nodes. Four rack-mounted, reduced size demonstrators of basic switching matrices have been designed and implemented scalable to real system sizes. The obtained good results in terms of bit error rate and hardware integration are reported, showing that ATM switches are feasible with state of-the-art optical technology