Concise synthesis of oxy-bridged bicyclic azasugar and thiosugar as potential glycosidase inhibitors

Aim To develop a concise method for the synthesis of bicyclic azasugar and thiosugar with novel scaffold. Methods The two primary hydroxyl groups of compound 1 were selectively protected with tosyl cloloride in pyridine, followed by ring-closure with sodium sulfide or primary amine to form the oxy-bridged bicyclic molecules in good yields. Results Two bicyclic azasugars and a thiosugar were produced from L-sorbose in several steps. Conclusion The described procedures provide an efficient method to synthesize bicyclic azasugar and thiosugar with novel scaffold as potential glycosidase inhibitors.

Crystal Structures and Antimicrobial Activity of Two Phosphorus Compounds

One phosphorus heterocycle compound 1, C13H13N2OPS, was synthesized by the reaction of Lawesson＇s reagent （LR） with o-phenylene diamine. The crystal belongs to the orthorhombic system, space group P212121 with a = 5.5274（11）, b = 8.1603（16）, c = 28.830（6） A, V = 1300.4（4） A^3, Z = 4, Mr= 276.28, Dc = 1.411 g/cm^3, F（000） = 576,μ = 0.360 mm^-1, R = 0.0259 and wR = 0.0652 for 1414 observed reflections with I 〉 2σ（I）. While compound 2, C14H17N2O2PS, was obtained as a ring-cleavage product of compound 1. This crystal is of monoclinic system, space group P21/c with a = 9.5619（19）, b = 21.879（4）, c = 7.3618（15） A, β= 103.03（3）°, V=1500.4（5） A^3, Z = 4, Mr= 308.33, Dc = 1.365 g/cm^3, F（000） = 648,μ = 0.325 mm^-1, R = 0.0383 and wR =0.0742 for 2283 observed reflections with I 〉 2σ（I）. Phosphorus atom in each compound bonds with sulfur and carbon atoms using sp^3 hybrid orbitals, and crystals of these two compounds are formed and stabilized by intermolecular hydrogen bonds and Van der Waals＇ forces. The special structure of compound 1 leads to its good antimicrobial activity against staphylococcus aureus.

Synthesis of (2R,3aR,8aR)-6-Chloro-3a-hydroxy-1,2,3,3a,8,8a- hexahydropyrrolo[2,3-b]indole-2-carboxylic Acid Methyl Ester by Reductive Cyclization

A synthesis of (2R,3aR,8aR)-6-chloro-3a-hydroxy-1,2,3,3a,8,8a-hexahydropyrrolo[2,3-b]indole-2-carboxylic acid methyl ester (1) was achieved. An aldol reaction with Garner aldehyde, a hydroxyl introduction by Davis re-agent, and a reductive intramolecular ring-closure reaction were served as the key steps. This piece of work pro-vides a new way to synthesize the analogues of hexahydropyrrolo[2,3-b]indole, starting from readily available chemical substrates and inexpensive reagents.

Achieving T-Type Photochromism through Generating Copper(I)Metallacyclopentadiene Biradical

Photochromism due to organometallic ring-closure through C−C linkage has never been attained.In this work,we report a preliminary approach to achieve T-type photochromism by creating a metallacyclopentadiene biradical under light irradiation.A class of CuPt2 phenylacetylide compounds was prepared with distinguished photochromic recyclability and durability,which involved the formation of thermally sensitive copper(I)-butadienyl,five-membered ring through copper(I)-participated ring-closure.Upon UV light irradiation,the metallacyclopentadiene with copper(I)center chelated by 1,3-butadiene-1,4-diyl biradical was generated through photochemical C-C linkage of two face-to-face oriented ethynyl units in close proximity,giving rise to a drastic change in UV-vis absorption spectrum.When UV light irradiation was ceased,decoloration occurred through thermal cycloreversion,which endowed the photochromic CuPt2 complexes with self-recovery characteristics.Electron paramagnetic resonance(EPR)spectral study confirmed a biradical feature of a ring-closed isomer.The thermal decoloration half-lives at ambient temperature were regulated from seconds to hours by increasing F substituents in phenylethynyl ligands.