Haitao Xi

Base-Controlled Selective Conversion of Michael Adducts of Malonates with Enones in the Presence of Iodine

An efficient base-controlled selective conversion of the Michael adducts of malonates with enones in the presence of iodine is reported. Highly functionalized cyclopropane, oxetane, and α-hydroxylmalonate derivatives are obtained selectively using DBU, Na(2)CO(3), and NaOAc as the base, respectively. O(2) was identified to be crucial to the formation of oxetane and α-hydroxylmalonate derivatives.

Study on relationship between the concentration of hydrocarbon groups in heavy oils and their structural parameter from 1H NMR spectra

More than 60 heavy oils samples, belonging to the hydrogen adding tail oil, catalytic oil slurry, catalytic heavy oil slurry and catalytic heavy tar waxy oil, which taken from different processing units in Nanjing Refinery, are analysed by 1H NMR and column chromatography. The analytical data of the heavy oils by two methods are compared and correlated, while good relationships between the specific area protons percentage in 1H NMR spectra and the contents of paraffinic and alicyclic hydrocarbons ((P+N)%), aromatic hydrocarbons (A%) are found. Our 1H NMR method in calculating the amount of (P+N) and A in heavy oils proved fast, convenient and reliable.

DMAP-Catalyzed [3 + 2] and [4 + 2] Cycloaddition Reactions between [60]Fullerene and Unmodified Morita–Baylis–Hillman Adducts in the Presence of Ac2O

One-step DMAP-catalyzed [3 + 2] and [4 + 2] cycloaddition reactions between C(60) and unmodified Morita-Baylis-Hillman adducts in the presence of Ac(2)O have been developed for the easy preparation of cyclopentene- and cyclohexene-fused [60]fullerene derivatives. When the MBH adducts bear an alkyl group, two different reaction pathways could be controlled selectively depending on the conditions.

3,6-Dibromo-7-ethyl­amino-4-methyl-2H-chromen-2-one

In title compound, C12H11Br2NO2, the coumarin ring system is almost planar, the two rings being inclined to one another by 1.40 (15)°. There are two short intramolecular interactions (N—H⋯Br and C—H⋯Br) involving the Br atoms. In the crystal, molecules stack along the a-axis direction via π–π interactions; the centroid–centroid distances vary from 3.6484 (19) to 3.7942 (19) Å.

3,6,8-Tribromo-7-ethyl­amino-4-methyl-2H-chromen-2-one

In the title molecule, C12H10Br3NO2, the 2H-chromen ring is essentially planar (r.m.s. deviation = 0.022 Å) with the ethylamino group oriented at 13.9 (5)° with respect to the ring. The molecular structure is stabilized by intramolecular N—H⋯Br and C—H⋯Br interactions.

25,26,27,28-Tetra-butoxy-5,11,17,23-tetra-tert-butyl-calix[4]arene chloro-form tetra-solvate dihydrate.

The title compound, C60H88O4·4CHCl3·2H2O, is the alkylated product of 5,11,17,23-tetra-tert-butylcalix[4]arene. It adopts a distorted cone conformation which leads to an open cavity. All the phenolic rings are tilted so that their tert-butyl groups are pitched away from the calix cavity. Two opposite aromatic rings are close to being perpendicular to one another [dihedral angle 85.0 (2)°], while the other pair of opposite rings is almost parallel [dihedral angle 8.1 (2)°], and adjacent phenolic rings are almost perpendicular [dihedral angles 82.4 (1) or 87.9 (1)°]. In the crystal, the water molecule and calixarene interact by way of O—H⋯O hydrogen bonds.

Synthesis of o-?-mercapto [poly(ethyleneoxy)]-o'-alkylhydroquinol derivatives and formation of novel pseudorotaxanes

A series of monofunctionalized hydroquinol oligoether chains terminated by thiols were designed and synthesized from unsymmetric starting materials in good yields by multi-procedure reactions at mild temperatures. In a thermodynamically controlled self-assembly process, several pseudorotaxanes based on the π-electron-rich hydroquinol oligoether thiols and π-electron deficient cyclobis(paraquat-p-phenylene) (CPQT) were formed. Furthermore, a gold cation was added to the self-assembly systems and 1H NMR studies on the thiol/Au systems revealed that Au3+ is an efficient terminal stopper of pseudorotaxanes or rotaxanes; the pseudorotaxane can be unthreaded or rethreaded at different temperatures. These could be a basis for the future development of mechanoelectrical and photoelectrical communication systems, and devices capable of storing and processing information.

Synthesis of Functionalized p-Phenylene Oxide Oligomers

Abstract Oligomers of p-phenylene oxides have been synthesized by coupling of substituted phenols and aryl bromides in the presence of cuprous chloride. The chain length varies from 2 to 5 phenyl rings functionalized at one end by an OH and OMe group and at the other end by an OH, OMe or NO2 functions. The oligomers could be used in material science and as building blocks in supramolecular chemistry. Methods for chemoselective demethylation of methoxy groups were developed.