In this paper we describe the phosphine-catalyzed [3 + 2], [3 + 3], [4 + 3], and [3 + 2 + 3] annulations of azomethine imines and allenoates. These processes mark the first use of azomethine imines in nucleophilic phosphine catalysis, producing dinitrogen-fused heterocycles, including tetrahydropyrazolo-pyrazolones, -pyridazinones, -diazepinones, and -diazocinones. Counting the two different reaction modes in the [3 + 3] cyclizations, there are five distinct reaction pathways—the choice of which depends on the structure and chemical properties of the allenoate. All reactions are operationally simple and proceed smoothly under mild reaction conditions, affording a broad range of 1,2-dinitrogen–containing heterocycles in moderate to excellent yields. A zwitterionic intermediate formed from a phosphine and two molecules of ethyl 2,3-butadienoate acted as a 1,5-dipole in the annulations of azomethine imines, leading to the [3 + 2 + 3] tetrahydropyrazolodiazocinone products. The incorporation of two molecules of an allenoate into an eight-membered-ring product represents a new application of this versatile class of molecules in nucleophilic phosphine catalysis. The salient features of this protocol—the facile access to a diverse range of nitrogen-containing heterocycles and the simple preparation of azomethine imine substrates—suggest that it might find extensive applications in heterocycle synthesis.

Measurements on densities (ρ), viscosities (η), and refractive indices (n D ) from (293.15 to 333.15) K and at 0.1 MPa along with the surface tensions (γ) at 298.15 K and 0.1 MPa for binary mixtures of 1,3-dimethyladamantane (1,3-DMA), 1-ethyladamantane (1-EA), and 1,3,5-trimethyladamantane (1,3,5-TMA) with 1-heptanol or cyclohexylmethanol have been carried out over the entire composition range. The experimental data are used to calculate the excess molar volumes (V m E ), viscosity deviations (Δη), molar refraction deviations (Δ Φ R), and surface tension deviations (Δγ). The V m E , Δη, Δ Φ R, and Δγ values have been fitted to the Redlich−Kister polynomial equation. From these excess or deviation functions, the molecular interactions and nonideality of the binary systems are discussed. The results are expected to provide fundamental data for understanding the properties of adamantane derivatives as potential components and the composition optimization of new high energy-density hydrocarbon fuels.

The aim of this contribution is to investigate the morphological responses of Hangzhou Bay, China, located immediately south of the Changjiang Estuary, to the drastic reduction of the sediment load from the Changjiang River and the large-scale coastal embankment over past decades. The spatial patterns of deposition and erosion, sediment volume changes, and the feedback with hydrodynamics and sediment transport were analyzed, on the basis of historical bathymetric and hydrographic data. The results show that the sedimentation rates in the bay have overall increased rather than decreased over the past decades, despite bed erosion having occurred in the northern bay-mouth. This reveals that the influence of the reduction in the Changjiang River sediment load on the

The research objective is to investigate the variations of sediment transport in outer Changjiang Estuary and adjacent Hangzhou Bay, induced by the decline of Changjiang River sediment discharge and massive land reclamation in the last three decades. A synchronous hydrographic survey was conducted along two transects (at the bay‐mouth and outer Changjiang Estuary, respectively) during the spring‐neap tides of January and July 2014. The results show that the suspended sediment grain size, current velocity, suspended sediment concentration (SSC), and the water and sediment fluxes varied with the tidal cycles. Quantitative correlations with the tidal range were found for SSC and fluxes. These data have been compared with those at the same hydrographic stations in the summer and winter of the early 1980s. Along the outer Changjiang Estuary transect, the SSCs and sediment fluxes decreased in the winter, but no apparent changes occurred in the summer. The SSCs in the northern Hangzhou Bay decreased in both summer and winter, while the southern bay mouth has evolved from a low SSC region to a high SSC region. The findings clarify that the SSC and sediment flux changes in this area have only an indirect connection to the dramatic riverine sediment decline, because the sediment resuspension by the strong tidal currents provided a major source. At the present stage, the impact of the riverine sediment decline is insignificant for the SSC variation off the Changjiang River mouth. Finally, a sediment flux model is proposed to explain and predict the morphological evolution trends.

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