Precise Synthesis of ChiralZ‐Allylamides by Cobalt‐Catalyzed Asymmetric Sequential Hydrogenations

Abstract

Asymmetric sequential hydrogenations of conjugated enynes have been developed using a Ph‐BPE‐CoI catalyst for the precise synthesis of chiral Z‐allylamides in high activity (up to 1000 substrate/catalyst (S/C)) and with excellent enantioselectivity (up to >99 % enantiomeric excess (ee)). Mechanism experiments and theoretical calculations support a cationic CoI/CoIII redox catalytic cycle. The catalytic activity difference between cobalt complexes of Ph‐BPE and QuinoxP* was explained by the process decomposition of rate‐determining step in the second hydrogenation.

Recent Development of Jumping Motions Based on Soft Actuators

“…Then the stored energy is released instantly, making the actuator jump. [ 86 ] This jumping motion was also consistent with the finite element simulation result. When the light is moved off, the film can revert back to the folded state again, and the next jump will happen.…”

“…The film size also affects jumping performance: in particular, the optimal jumping characteristics can be achieved at a certain ratio of length and width. [ 86 ] Additionally, the jumping height decreases as the film thickness of the jumping actuator increases. [ 69 ] The continuous jumping of the actuating film can be realized by changing the light direction or controlling the beam intensity distribution or supplying a certain frequency voltage.…”

Photothermal‐Responsive Crosslinked Liquid Crystal Polymers

“…[127] Copyright 2022, Wiley-VCH GmbH), and c) the time-dependent jump behavior of a double-folded LCE ribbon jumping robot (Reproduced with permission. [128] Copyright 2023, Wiley-VCH GmbH).…”

Recent Advances in Ynenamine Chemistry

“…Recently, the same group developed an efficient method for the synthesis of chiral Z-allylamides via Ph-BPE-Co (I) -catalyzed asymmetric sequential hydrogenation. [52] According to mechanistic investigations, the carbonyl group in the QuinoxP* coordinated complex XXVII was more tightly bound to the Co center than that in the Ph-BPE coordinated complex XXIX. The tighter binding of the carbonyl group to the Co center in the QuinoxP* coordinated complex made carbonyl dissociation more difficult, thus protecting the alkyne group from being hydrogenated.…”

“…The authors proposed a Co (I) /Co (III) catalytic cycle and verified the activating effect of Zn 2+ , generated from the zinc reduction of the Co (II) complex. Recently, the same group developed an efficient method for the synthesis of chiral Z ‐allylamides via Ph‐BPE‐Co (I) ‐catalyzed asymmetric sequential hydrogenation [52] . According to mechanistic investigations, the carbonyl group in the QuinoxP* coordinated complex XXVII was more tightly bound to the Co center than that in the Ph‐BPE coordinated complex XXIX .…”