Optical Switching of Self-Assembly and Disassembly of Noncovalently Connected Amphiphiles

A hydrophobic compound, which we name 3C18-Azo, containing an azo head and three 18 C alkyl chains has the capacity to form an amphiphile by capping it with a cyclodextrin (CD) by inclusion complexation. The amphiphilic compound self-assembles into vesicles in water. Optical switching of the assembly and disassembly is realized by alternating visible and UV irradiation, which causes the isomerization of the azo groups, thus affecting their complexation with the CDs

Microwave-Assisted Synthesis of Diaryl Ethers without Catalyst

Diaryl ethers have been prepared by direct coupling of phenols including those that bear a strong electron-attracting substituent to electron-deficient aryl halides through SNAr-based addition reactions with assistance of microwave irradiation in high to excellent yields within 5−10 min. No catalysts were required under our conditions

K₂CO₃-Catalyzed Michael Addition−Lactonization Reaction of 1,2-Allenyl Ketones with Electron-Withdrawing Group Substituted Acetates. An Efficient Synthesis of α-Pyrone Derivatives

α-Pyrone derivatives were synthesized via the base catalyzed or promoted reaction of 1,2-allenyl ketones and electron-withdrawing group substituted acetates. The reaction was believed to proceed through a Michael addition C−C double-bond migration−lactonization process

Dual Reversible Self-Assembly of PNIPAM-Based Amphiphiles Formed by Inclusion Complexation

β-Cyclodextrin (β-CD)-ended linear poly(N-isopropylacrylamide) (β-CD-PNIPAM) and Frechét-type benzyl ether dendron with an azobenzene group (Gx-Azo) at the apex site form noncovalently connected amphiphiles (NCCAs) by inclusion complexation between the azo group and β-CD. The NCCAs self-assemble into vesicles in water. Optical switching of the assembly and disassembly is realized by alternating visible and UV irradiation, which causes the isomerization of the azo groups and their consequent complexation and decomplexation with β-CD. The structure and morphology of the vesicles were characterized by dynamic light scattering (DLS), static light scattering (SLS), SEM, TEM, and AFM. These photoresponsive vesicles can further respond to heat stimuli resulting in reversible aggregation and disaggregation of the vesicles

On the 6-Exo Atom Transfer Radical Cyclization Reactions of 3-Butenyl 2-Iodoalkanoates

Bis(tributyltin)-initiated atom transfer cyclization reactions of 3-butenyl iodoalkanoates in the presence of BF3·OEt2 as the catalyst afforded the 6-exo cyclization products as a mixture of 3,4-cis- and trans-substituted tetrahydro-2H-pyran-2-ones in 53−71% yield with the major isomers being the cis ones. Ab initio calculations at the B3LYP/6-31G* level on the transition states of the radical cyclization and on the cyclized products revealed that the reactions are kinetically controlled and the transition states for the 6-exo radical cyclization are in boat conformations. Moreover, the cis-oriented transition states are of lower energy than the corresponding trans-oriented ones, which are in excellent agreement with experimental results

On the 6-Exo Atom Transfer Radical Cyclization Reactions of 3-Butenyl 2-Iodoalkanoates

Bis(tributyltin)-initiated atom transfer cyclization reactions of 3-butenyl iodoalkanoates in the presence of BF3·OEt2 as the catalyst afforded the 6-exo cyclization products as a mixture of 3,4-cis- and trans-substituted tetrahydro-2H-pyran-2-ones in 53−71% yield with the major isomers being the cis ones. Ab initio calculations at the B3LYP/6-31G* level on the transition states of the radical cyclization and on the cyclized products revealed that the reactions are kinetically controlled and the transition states for the 6-exo radical cyclization are in boat conformations. Moreover, the cis-oriented transition states are of lower energy than the corresponding trans-oriented ones, which are in excellent agreement with experimental results

On the 6-Exo Atom Transfer Radical Cyclization Reactions of 3-Butenyl 2-Iodoalkanoates

Bis(tributyltin)-initiated atom transfer cyclization reactions of 3-butenyl iodoalkanoates in the presence of BF3·OEt2 as the catalyst afforded the 6-exo cyclization products as a mixture of 3,4-cis- and trans-substituted tetrahydro-2H-pyran-2-ones in 53−71% yield with the major isomers being the cis ones. Ab initio calculations at the B3LYP/6-31G* level on the transition states of the radical cyclization and on the cyclized products revealed that the reactions are kinetically controlled and the transition states for the 6-exo radical cyclization are in boat conformations. Moreover, the cis-oriented transition states are of lower energy than the corresponding trans-oriented ones, which are in excellent agreement with experimental results

On the 6-Exo Atom Transfer Radical Cyclization Reactions of 3-Butenyl 2-Iodoalkanoates

Bis(tributyltin)-initiated atom transfer cyclization reactions of 3-butenyl iodoalkanoates in the presence of BF3·OEt2 as the catalyst afforded the 6-exo cyclization products as a mixture of 3,4-cis- and trans-substituted tetrahydro-2H-pyran-2-ones in 53−71% yield with the major isomers being the cis ones. Ab initio calculations at the B3LYP/6-31G* level on the transition states of the radical cyclization and on the cyclized products revealed that the reactions are kinetically controlled and the transition states for the 6-exo radical cyclization are in boat conformations. Moreover, the cis-oriented transition states are of lower energy than the corresponding trans-oriented ones, which are in excellent agreement with experimental results

On the 6-Exo Atom Transfer Radical Cyclization Reactions of 3-Butenyl 2-Iodoalkanoates

Bis(tributyltin)-initiated atom transfer cyclization reactions of 3-butenyl iodoalkanoates in the presence of BF3·OEt2 as the catalyst afforded the 6-exo cyclization products as a mixture of 3,4-cis- and trans-substituted tetrahydro-2H-pyran-2-ones in 53−71% yield with the major isomers being the cis ones. Ab initio calculations at the B3LYP/6-31G* level on the transition states of the radical cyclization and on the cyclized products revealed that the reactions are kinetically controlled and the transition states for the 6-exo radical cyclization are in boat conformations. Moreover, the cis-oriented transition states are of lower energy than the corresponding trans-oriented ones, which are in excellent agreement with experimental results

On the 6-Exo Atom Transfer Radical Cyclization Reactions of 3-Butenyl 2-Iodoalkanoates

Bis(tributyltin)-initiated atom transfer cyclization reactions of 3-butenyl iodoalkanoates in the presence of BF3·OEt2 as the catalyst afforded the 6-exo cyclization products as a mixture of 3,4-cis- and trans-substituted tetrahydro-2H-pyran-2-ones in 53−71% yield with the major isomers being the cis ones. Ab initio calculations at the B3LYP/6-31G* level on the transition states of the radical cyclization and on the cyclized products revealed that the reactions are kinetically controlled and the transition states for the 6-exo radical cyclization are in boat conformations. Moreover, the cis-oriented transition states are of lower energy than the corresponding trans-oriented ones, which are in excellent agreement with experimental results