A highly chemo- and regioselective [4 + 2] formal cycloaddition of (Z)-3-iodo allylic nucleophiles and allenamides catalyzed by palladium is reported.

No abstract

A mild and efficient type of Pd/Cu-catalyzed allenamide allyl acetate reaction with terminal alkynes affording polyfunctionalized 2,3-dihydropyrrole derivatives is reported. Allenamide substrates went through two π-allyl palladium complex processes, and then it was trapped by terminal alkynes on the distal position via a Sonogashira reaction. Two new Csp 3 À Csp 2 and Csp 3 À Csp bonds were efficiently constructed in one pot.

We propose a new approach to realize switchable mode operation in a few-mode erbium-doped fiber laser. The ring fiber laser structure is constructed with a core-offset splicing between single-mode fiber and dual-mode fiber. Stable operating on the fundamental mode laser and second-order mode laser individually or simultaneously is realized by appropriately adjusting the state of the polarization controller and bending status of the few-mode fiber Bragg grating. The narrow 3 dB linewidth less than 0.02 nm and high optical signal to noise ratio more than 42 dB are obtained for both modes in either separate laser or simultaneous laser operating conditions.

No abstract