γ-Lactam derivatives with multiple contiguous stereogenic carbon centers are ubiquitous in physiologically active compounds. The development of straightforward and reliable synthetic routes to such chiral structural motifs in a stereocontrolled manner should thus be of importance. Herein, we report a strategy to construct polycyclic γ-lactam derivatives that contain more than two contiguous stereogenic centers in an enantioselective as well as atom-economic manner. Moreover, we have achieved the first enantioselective synthesis of strigolactam derivative GR-24, a racemic variant of which is a potential seed germination stimulator and plantgrowth regulator. A key of the procedure presented here is a nickel(0)/chiral phosphoramidite-catalyzed asymmetric [2+2+1] carbonylative cycloaddition between readily accessible ene-imines and carbon monoxide, which proceeded enantioselectively to furnish up to 90% ee (>99% ee after recrystallization). The results of mechanistic studies, including the isolation of a chiral heteronickelacycle, support that the enantioselectivity on the two contiguous carbon atoms of the γ-lactams is determined during the oxidative cyclization on nickel(0).

The carbon-carbon (C-C) bond activation of [n]cycloparaphenylenes ([n]CPPs) by a transition-metal complex is herein reported. The Pt complex Pt(PPh ) regioselectively cleaves two C-C σ bonds of [5] CPP and [6]CPP to give cyclic dinuclear platinum complexes in high yields. Theoretical calculations reveal that the relief of ring strain drives the reaction. The cyclic complex was further transformed into a cyclic diketone by using a CO insertion reaction.

The nickel(0)-catalyzed carbonylative cycloaddition of 1,5- and 1,6-ene-imines with carbon monoxide (CO) is reported. Key to this reaction is the efficient regeneration of the catalytically active nickel(0) species from nickel carbonyl complexes such as [Ni(CO) L]. A variety of tri- and tetracyclic γ-lactams were thus prepared in excellent yields with 100 % atom efficiency. Preliminary results on asymmetric derivatives promise potential in the synthesis of enantioenriched polycyclic γ-lactams.

The carbon-carbon (CÀC) bond activation of [n]cycloparaphenylenes ([n]CPPs) by atransition-metal complex is herein reported. The Pt 0 complex Pt(PPh 3 ) 4 regioselectively cleaves two C À C s bonds of [5] CPP and [6]CPP to give cyclic dinuclear platinum complexes in high yields.Theoretical calculations reveal that the relief of ring strain drives the reaction. The cyclic complex was further transformed into acyclic diketone by using aCOinsertion reaction.Cycloparaphenylenes (CPPs;S cheme 1) have attracted immense scientific interest because of their fascinating structure,p hysical properties,a nd potential applications in materials science.T his interest originates from their nonplanar and conjugated structure corresponding to the shortest cyclic structural unit of an armchair carbon nanotube. [1] After the successful bottom-up organic synthesis of CPPs by Jasti and Bertozzi et al., [2] Itami et al., [3] and Yamago et al., [4] CPPs of various sizes, [5][6][7] and their derivatives, [8] are available,a nd their unique physical properties,s uch as size-dependent photophysical [9] and redox properties [7a, 10] and host-guest chemistry, [11] have been unveiled. In particular, recent achievements in the large-scale synthesis of CPPs by the groups Supportinginformation and the ORCID identification number(s) for the author(s) of this article can be found under: https://doi.org/10.1002/anie.201806591. Scheme 1. Possible reactions of [n]CPP with atransition-metal complex. Ma nd Ld enote metal and ligand, respectively. Scheme 2. The CÀCactivation of [n]CPPs and subsequent transformation.

The nickel(0)-catalyzed carbonylative cycloaddition of 1,5-and 1,6-ene-imines with carbon monoxide (CO) is reported. Keytothis reaction is the efficient regeneration of the catalytically active nickel(0) species from nickel carbonyl complexes such as [Ni(CO) 3 L].Avariety of tri-and tetracyclic g-lactams were thus prepared in excellent yields with 100 % atom efficiency.Preliminary results on asymmetric derivatives promise potential in the synthesis of enantioenriched polycyclic g-lactams.