Ag(I)-Catalyzed Addition of Cyclopropenones and Alcohols via C—C Bond Cleavage

An efficient method for the synthesis of α-phenylcinnamates via silver catalyzed C—C bond activation reaction of cyclopropenone and alcohol was developed.This protocol features a simple reaction system,specific regioselectivity,good functional group compatibility and good yields.It is of great significance for the later modification of natural products.

Catalytic[3+3]Annulation ofβ-Ketoethers and Cyclopropenones via C(sp^(3))-O/C-C Bond Cleavage under Transition-Metal Free Conditions

Main observation and conclusion The efficient cleavage of carbon-oxygen(C—O)bond is highly important for the transformation of oxygen-rich biomass and industry chemicals.Herein,an efficient[3+3]annulation ofβ-ketoethers with cyclopropenones in the presence of catalytic base has been developed,which proceeds through the C(sp^(3))—O bonds cleavage inβ-ketoethers and C—C bond cleavage in cyclopropenones under transition-metal free conditions.The cleavage of C(sp^(3))—O bonds in alkyl alkyl ethers and aryl alkyl ethers was realized.The reaction featured excellent functional group compatibility and chemoselectivity,affording various 2-pyrones in good to excellent yields under mild conditions and simple operation.

Difluorocarbene Chemistry： A Simple Transformation of 3,3-gem-Difluorocyclopropenes to Cyclopropenones

The cycloaddition reactions of a-acetyoxyl propynes with difluorocarbene, generated from the decomposition of FSO2CF2CO2SiMe3 in DG in the presence of 10% of NaF at 120℃ gave readily a-acetyoxyl gem-difluorocyclopropenes. When these fluorinated compounds were hydrolyzed under alkaline condition at 0℃, α-hydroxyl cyclopropenones were produced predominantly whereas treated with catalytic amounts of BF3·Et2O in Et2O, α-acetyoxyl cyclopropenones were obtained.

Synthesis and Optical Properties of Polyaryl 2-(Pyridin-2-yl)phenol-Based Four-Coordinate Organoboron Complexes

Comprehensive Summary A family of polyaryl 2-(pyridin-2-yl)phenol-based four-coordinate organoboron complexes were prepared in good yields via deconstructive cycloaromatization of indolizines,cyclopropenones,and boric acids.The photoluminescence measurements have revealed that these N,Oπ-conjugated tetracoordinate boron complexes display bright fluorescence,large Stokes shifts,and good quantum yields(Φlum=0.15-0.45).In addition,the DFT calculations were carried out to deepen the understanding of the electronic structures and optoelectronic properties of these structurally unprecedented tetracoordinate boron complexes.

Diphenyl cyclopropenone-centered polymers for site-specific CO-releasing and chain dissociation

The synthesis and stimuli-responsiveness of a diphenyl cyclopropenone(DPCP)-centered poly(methyl acrylate)(PMA)are presented.DPCP-centered PMA could release carbon monoxide(CO)upon UV light in a switched on-and-off manner.The CO-releasing process can be reported by the variations in photoluminescence spectra.In addition,DPCP moiety covalently embedded in the crosslinked polyurethane could also release CO under UV light.Of special,DPCP-centered PMA in solution was selectively dissociated at the phenol ester bond under the ultrasound,and a force-induced hydrolyzation reaction was revealed by D20 exchanging^1 H NMR spectra.The kinetic study reveals that small quantity of water could enhance the chain scission rate.This work provides a DPCP-centered polymer for sitespecific CO-releasing and chain dissociation.