A method of using intense Laguerre-Gaussian (LG) laser pulse is proposed to generate ultrarelativistic (multi-GeV) electron beams with controllable helical structures based on a hybrid electron acceleration regime in underdense plasmas, where both the longitudinal charge-separation electric field and transverse laser electric field play the role of accelerating the electrons. By directly interacting with the LG laser pulse, the topological structure of the accelerated electron beam is manipulated and it is spatially separated into multi-slice helical bunches. These results are clearly demonstrated by our three-dimensional particle-in-cell simulations and explained by a theoretical model based on electron phase-space dynamics. This novel regime offers a new degree of freedom for manipulating ultrashort and ultrarelativistic electrons, and it provides an efficient way for generating high-energy highangular-momentum helical electron beams, which may find applications in wide-ranging areas.

Organocatalytic ester activation is developed for a highly selective cascade reaction between saturated esters and amino enones. The reaction involves activation of the β-carbon atom of the ester as a key step. This method allows a single-step access to multicyclic oxoquinoline-type heterocycles with high enantiomeric ratios.

Direct β-carbon activation of propionic acid (C2H5CO2H) by carbene organocatalysis has been developed. This activation affords the smallest azolium homoenolate intermediate (without any substituent) as a 3-carbon nucleophile for enantioselective reactions. Propionic acid is an excellent raw material because it is cheap, stable, and safe. This approach provides a much better solution to azolium homoenolate synthesis than the previously established use of acrolein (enal without any substituent), which is expensive, unstable, and toxic.

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