Synthesis of Axially Chiral Biaryls through Cobalt(II)-Catalyzed Atroposelective C-H Arylation.

Highly efficient synthesis of axially chiral biaryl amines through cobalt-catalyzed atroposelective C-H arylation using easily accessible cobalt(II) salt and salicyloxazoline ligand has been reported. This methodology provides a straightforward and sustainable access to a broad range of enantioenriched biaryl-2-amines in good yields (up to 99 %) with excellent enantioselectivities (up to 99 % ee). The synthetic utility of the unprecedented method is highlighted by its scalability and diverse transformations.

Pd(II)-Catalyzed Atroposelective C-H Allylation: Synthesis of Enantioenriched -Aryl Peptoid Atropisomers.

A Pd-catalyzed atroposelective C-H allylation with 1,1-disubstituted alkenes was developed for the synthesis of enantioenriched -aryl peptoid atropisomers via β-H elimination using commercially available and inexpensive L-Glu-OH as a chiral ligand. Exclusive allylic selectivity was achieved. Additionally, a series of enantioenriched -aryl peptoid atropisomers were obtained in synthetically useful yields with excellent enantioselectivities (up to 90% yield and 97% ee).

Copper-catalyzed monoselective C-H amination of ferrocenes with alkylamines.

A copper-catalyzed mono-selective C-H amination of ferrocenes assisted by 8-aminoquinoline is presented here. A range of amines, including bioactive molecules, were successfully installed to the -position of ferrocene amides with high efficiency under mild conditions. A range of functionalized ferrocenes were compatible to give the aminated products in moderate to good yields.

Brønsted Acid-Catalyzed Formal (3+3)-Annulation of Propargylic (Aza)--Quinone Methides with 4-Hydroxycoumarins and 1,3-Dicarbonyl Compounds.

Herein, we describe a highly effective 1,8-conjugate-addition-mediated formal (3+3)-annulation of (aza)--quinone methides generated from propargylic alcohols with 4-hydroxycoumarins and 1,3-dicarbonyl compounds under the catalysis of a Brønsted acid. This methodology affords efficient and practical access to synthetically important and highly functionalized pyranocoumarins and pyrans in excellent yields under mild conditions. Importantly, these products exhibit impressive inhibitory activity toward α-glucosidase.

Palladium-Catalyzed Directed Atroposelective C-H Allylation via β-H Elimination: 1,1-Disubstituted Alkenes as Allyl Surrogates.

Transition-metal-catalyzed dehydrogenative C-H allylation with 1,1-disubstituted alkenes via β-H elimination remains challenging, because of the low reactivity and difficulty of controlling selectivity. Herein, the development of a Pd(II)-catalyzed directed atroposelective C-H allylation with methacrylates is described. Exclusive allylic selectivity was achieved.

Transmission of single-carrier 400G signals (515.2-Gb/s) based on 128.8-GBaud PDM QPSK over 10,130- and 6,078 km terrestrial fiber links.

We experimentally demonstrate the coherent transmission system with the highest ETDM-based symbol rate of 128.8-GBaud over record breaking distances. We successfully transmitted single-carrier 515.

Experimental demonstration of iterative post-equalization algorithm for 37.5-Gbaud PM-16QAM quad-carrier Terabit superchannel.

We experimentally demonstrate a quad-carrier 1-Tb/s solution with 37.5-GBaud PM-16QAM signal over 37.5-GHz optical grid at 6.

Optical independent-sideband modulation for bandwidth-economic coherent transmission.

We proposed and implemented a bandwidth-economic coherent optical transmission technology using optical independent-sideband (O-ISB) modulation. Generation of two software-defined, 30-GBd O-ISB channels per wavelength sharing one set of transmitter hardware was demonstrated, which was made possible by digital single-sided up-conversion, channel pre-equalization and optical IQ modulation with precise amplitude and delay matching between driving signals. With 120-Gb/s PM-QPSK per O-ISB channel, we successfully delivered 16 O-ISB channels in 8 wavelengths at 3.

Performance comparison of spectrum-narrowing equalizations with maximum likelihood sequence estimation and soft-decision output.

Maximum likelihood sequence estimation (MLSE) offers effective equalizations for bandwidth-limited optical signal on mitigation towards inter-symbol-interference (ISI) impairment. In this paper, we provide the first comprehensive comparisons and analysis of three post-compensation algorithms on the same modeling platform for high spectral-efficiency (SE) optical systems employing the spectral prefiltering. Those algorithms include 1-tap constant modulus algorithm (CMA) and 3-tap MLSE, regular CMA and digital filter with 2-tap MLSE, and constant multi-modulus algorithm (CMMA) with 2-tap MLSE.

Transmission of 8 × 480-Gb/s super-Nyquist-filtering 9-QAM-like signal at 100 GHz-grid over 5000-km SMF-28 and twenty-five 100 GHz-grid ROADMs.

We experimentally demonstrate a highly filtering-tolerant multi-modulus equalization (MMEQ) process for very aggressively spectrum-shaped 9-ary quadrature-amplitude-modulation (9-QAM)-like polarization division multiplexing quadrature phase shift keying (PDM-QPSK) signal to achieve 400-Gb/s wavelength-division-multiplexing (WDM) channels on the 100-GHz grid for ultra-long-haul reach and high tolerance of the filter narrowing effect caused by reconfigurable optical add-drop multiplexers (ROADMs). We successfully transmitted 8 channels 480-Gb/s super-Nyquist (channel occupancy much less than signal baud rate) WDM signals at 100-GHz grid over 25 × 200 km conventional single-mode fiber-28 (SMF-28) with post Raman amplification and 25 ROADMs at a net spectral efficiency (SE) of 4b/s/Hz, after excluding the 20% soft-decision forward-error-correction (FEC) overhead. The system performance is significantly enhanced by the MMEQ based on 9-QAM-like constellations compared to the conventional 4 point QPSK constellation.

WDM transmission of 108.4-Gbaud PDM-QPSK signals (40 × 433.6-Gb/s) over 2800-km SMF-28 with EDFA-only.

We experimentally demonstrated the transmission of 40 × 433.6-Gb/s Nyquist wavelength-division-multiplexing (N-WDM) optical time-division-multiplexing (OTDM) over 2800-km single-mode fiber (SMF)-28 with Erbium-doped fiber amplifier (EDFA)-only amplification, adopting polarization-division-multiplexing carrier-suppressed return-to-zero quadrature-phase-shift-keying (PDM-CSRZ-QPSK) modulation as well as post filter and 1-bit maximum likelihood sequence estimation (MLSE). Each channel occupies 100 GHz, yielding a spectral efficiency of 4.

60 GHz millimeter-wave gigabit wireless services over long-reach passive optical network using remote signal regeneration and upconversion.

This study proposed and experimentally demonstrated a cost-efficient scheme that can deliver 60 GHz millimeter-wave (mm-wave) multi-gigabit wireless services over 125 km long-reach passive optical networks (PONs) without any dispersion compensation. By introducing a remote local exchange (LE) stage with robust signal regeneration and all-optical upconversion functionalities, the proposed long-reach optical-wireless access network can easily accommodate over 128 users with 2.5 Gb/s shared bandwidth as well as shifting the capital expenditure of multiple hybrid optical network units (ONUs) toward single LE headend.