Synthetic organic chemistry with 2-ethoxy-2-(phenylselenenyl)perfluoroalk-2-enenitrile: application to alpha-cyanoperfluoroacylation of aldehydes

(Z)- and (E)-2-Ethoxyperfluoro-2-(phenylselenenyl)alk-2-enenitriles 2-4 prepared by our original method underwent transmetalation on treatment with n-BuLi or EtMgBr, and the successive reaction with aldehyde and ketones afforded the corresponding allylic alcohols 10a-f, 9a, and 11a,b in good to high yields. Hydrolysis of the alcohols gave alpha-cyano-alpha,beta-unsaturated perfluoroalkyl ketones 13a-c, 13e, 12a, and 15a. alpha-Cyanoperfluoroalkyl ketones were easily converted to alpha,beta-unsaturated 3-aryl-2-cyanoallylic alcohols 18-22 having interesting biological activities and chemical reactivities.     

A Novel Synthesis of α-Tellanyl α,β-Unsaturated Aldehydes Using α-Tellanyl β-Alkoxyalkenyl Lithiums

Abstract

β-Ethoxy-α-phenyltellanylvinyl lithiums were successfully generated in situ from phenyltellanylacetaldehyde diethyl acetal with lithium 2,2,6,6-tetrame-thylpiperidide (LTMP) and underwent methylation or nucleophilic addition with aldehydes and ketones. The successive dehydration of the allylic alcohols with trimethylsilyl trifluoromethanesulfonate (TMSOTf) gave α-phenyltellanyl α,β-unsaturated aldehydes, which transformed to some useful compounds.     

Synthesis of 4,5-fused tricyclic quinolines via an acid-promoted intramolecular Friedel–Crafts allenylation of aniline derivatives

A novel method for synthesizing 4,5-fused tricyclic quinoline derivatives based on an acid-promoted intramolecular Friedel–Crafts allenylation of anilines. Using aryl group-substituted propargyl alcohol derivatives with a meta-substituted N-Boc aniline unit as substrates, a four-step reaction sequence involving an acid-promoted intramolecular Friedel–Crafts allenylation of anilines, an acid-promoted intramolecular C–N bond formation, deprotection of the Boc group, and air oxidation proceeded in a single pot, producing the corresponding 4,5-fused tricyclic quinoline derivatives in 31–84% yield.     

“Clickable” affinity ligands for effective separation of glycoproteins

In this paper, we present a new modular approach to immobilize boronic acid ligands that can offer effective separation of glycoproteins. A new “clickable” boronic acid ligand was synthesized by introducing a terminal acetylene group into commercially available 3-aminophenyl boronic acid. The clickable ligand, 3-(prop-2-ynyloxycarbonylamino)phenylboronic acid (2) could be easily coupled to azide-functionalized hydrophilic Sepharose using Cu(I)-catalyzed 1,3-dipolar cycloaddition reaction under mild condition. Compared to other boronic acid affinity gels, the new affinity gel displayed superior effectiveness in separating model glycoproteins (ovalbumin and RNase B) from closely related bovine serum albumin and RNase A in the presence of crude Escherichia coli proteins. Because of the simplicity of the immobilization through “click chemistry”, the new ligand 2 is expected to not only offer improved glycoprotein separation in other formats, but also act as a useful building block to develop new chemical sensors for analysis of other glycan compounds.     

Origin of metallic states at the heterointerface between the band insulators LaAlO3 and SrTiO3

We have studied the electronic structure at the heterointerface between the band insulators LaAlO3 and SrTiO3 using in situ photoemission spectroscopy. Our experimental results clearly reveal the formation of a notched structure on the SrTiO3 side due to band bending at the metallic LaAlO3/TiO2-SrTiO3 interface. The structure, however, is absent at the insulating LaAlO3/SrO-SrTiO3 interface. The present results indicate that the metallic states originate not from the charge transfer through the interface on a short-range scale but from the accumulation of carriers on a long-range scale.     

Copper-catalyzed complete regio- and stereoselective cyclization of 1-aryl-3-sulfanyl-4-oxahepta-1,6-diynes triggered by alkynylation

Copper(I)-catalyzed alkynylation-cyclization of 4-oxahepta-1,6-diynes 1 with a wide variety of terminal alkynes proceeded to give (3E,4Z)-3-(phenylsulfanylmethylene)-4-(2-propynylidene)tetrahydrofuran-2-yl]benzenes 2aa-he in high yields with complete regio- and stereoselectivity.     

Organotin-catalyzed highly regioselective thiocarbonylation of nonprotected carbohydrates and synthesis of deoxy carbohydrates in a minimum number of steps

Nonprotected carbohydrates: The catalytic regioselective thiocarbonylation of carbohydrates by using organotin dichloride under mild conditions was demonstrated. The reaction afforded various deoxy saccharides in high yields and excellent regioselectivity in a minimum number of steps. The regioselectivity of the thiocarbonylation is attributed to the intrinsic character of the carbohydrates based on the stereorelationship of their hydroxy groups (see scheme).