Nickel-catalyzed carboxylation of aryl and vinyl chlorides employing carbon dioxide has been developed. The reactions proceeded under a CO(2) pressure of 1 atm at room temperature in the presence of nickel catalysts and Mn powder as a reducing agent. Various aryl chlorides could be converted to the corresponding carboxylic acid in good to high yields. Furthermore, vinyl chlorides were successfully carboxylated with CO(2). Mechanistic study suggests that Ni(I) species is involved in the catalytic cycle.

Carbon dioxide (CO 2 ) is a readily available and renewable chemical feedstock, although thermodynamic considerations limit its widespread use in chemical reactions.[1] For effective utilization of CO 2 , transition-metal catalysts are required. [2] Useful transformations of CO 2 such as 1) cycloaddition via a metallacycle [3] and 2) carboxylation of organozinc and organoboron compounds [4] have been reported to date. Besides these reactions, the hydrocarboxylation [5] of C-C multiple bonds using CO 2 is also very promising. The first example of hydrocarboxylation using CO 2 was achieved using a nickelcatalyzed electrochemical reaction with alkynes,[5a] 1,3-diynes,[5b] and 1,3-enynes [5c] as substrates. Later, in supercritical CO 2 , palladium-catalyzed hydrocarboxylation of terminal alkenes was reported.[5d,e] As for more efficient hydrocarboxylations, recent nickel-catalyzed reaction of styrenes [5f] and palladium-catalyzed reaction of allenes [5g] were reported with either ZnEt 2 [5f,g] or AlEt 3[5g] as reducing agents. These reactions are very useful, but such strong and extremely airsensitive reducing agents were indispensable in the reactions. Herein we report the copper-catalyzed hydrocarboxylation of alkynes using CO 2 (balloon). [6,7] The use of mild and easy-tohandle hydrosilane [8] as a reducing agent realizes highly efficient hydrocarboxylation of alkynes to afford a,b-unsaturated carboxylic acids (2; Scheme 1).The hydrocarboxylation of diphenylacetylene (1 a) with CO 2 (balloon) was carried out using HSi(OEt) 3 as a reducing agent in 1,4-dioxane (Table 1). The yield of (E)-2,3-diphenyl-2-propenoic acid (2 a) was determined by GC methods after derivatization [9] to the corresponding methyl ester 2 aMe. By employing [IPrCuCl] + tBuONa (Table 1, entry 1) or [IMesCuCl] + tBuONa (Table 1, entry 2) as a catalyst, 2 aMe was obtained in only trace amounts and 49 % yield, respectively. In the latter case, a considerable amount (19 % yield) of cis-stilbene (3 a) was observed as a by-product. When [IPrCuF] [10] was used as a catalyst, 2 aMe was obtained in 41 % yield while reducing the formation of 3 a to 3 % (Table 1, entry 3). The new complex [IMesCuF] was synthesized from [IMesCuCl] similar to the synthesis of [IPrCuF], and its structure was confirmed by X-ray crystallography (Scheme 2).[9] As a result, [IMesCuF] was a much more Scheme 1. Hydrocarboxylation of alkynes using CO 2 and hydrosilanes.

A copper catalyst bearing a suitable Xantphos derivative or NHC ligand was found to be highly efficient for the selective semihydrogenation of non‐polar unsaturated compounds using a mixture of a silane and an alcohol as reducing agent. The catalytic system was useful for the selective semihydrogenation of internal alkynes to (Z)‐alkenes with suppression of overreduction to the corresponding alkanes. Furthermore, semihydrogenations of terminal alkyne, 1,2‐diene, 1,3‐diene, 1,3‐enyne and 1,3‐diyne systems were also achieved selectively.

Chlorophylls (Chls) are crucial for capturing light energy for photosynthesis. Although several genes responsible for Chl biosynthesis were characterized in rice (Oryza sativa), the genetic properties of the hydrogenating enzyme involved in the final step of Chl synthesis remain unknown. In this study, we characterized a rice light-induced yellow leaf 1-1 (lyl1-1) mutant that is hypersensitive to high-light and defective in the Chl synthesis. Light-shading experiment suggested that the yellowing of lyl1-1 is light-induced. Map-based cloning of LYL1 revealed that it encodes a geranylgeranyl reductase. The mutation of LYL1 led to the majority of Chl molecules are conjugated with an unsaturated geranylgeraniol side chain. LYL1 is the firstly defined gene involved in the reduction step from Chl-geranylgeranylated (ChlGG) and geranylgeranyl pyrophosphate (GGPP) to Chl-phytol (ChlPhy) and phytyl pyrophosphate (PPP) in rice. LYL1 can be induced by light and suppressed by darkness which is consistent with its potential biological functions. Additionally, the lyl1-1 mutant suffered from severe photooxidative damage and displayed a drastic reduction in the levels of α-tocopherol and photosynthetic proteins. We concluded that LYL1 also plays an important role in response to high-light in rice.

As one of the most promising cathode materials for next generation energy storage applications, spinel LiNi0.5Mn1.5O4 (LNMO) has been highlighted due to many advantages. However, it is still hindered by poor electrochemical stability derived from the bulk/interface structure degradation and side-reactions under high working voltage. In this work, fast ion conductor Li3V2(PO4)3 (LVPO) is adopted to modify the surface of spinel LNMO by a one-step facile method to harvest the maximum benefit of interface properties. It is found that 1 wt.% LVPO-LNMO exhibits the most excellent cycling performances, retaining a great capacity retention of 87.8 % after 500 cycles at room temperature and 82.4 % for 150 cycles at 55 o C. Moreover, the rate performance is also significantly improved (90.4 mAh g-1 under 20 C). It is revealed that the LVPO-involved layer could effectively suppress the surface side-reactions under high working voltage, which mainly contribute an improved interface with desirable structure stability and excellent kinetics behaviour without sacrificing the surface electrochemical activity in electrochemical environment. Thus, the dissolution of transition metal ions is effectively mitigated with avoiding further structure degradation of bulk material. Especially, it is also established that the vanadium (V) ions in LVPO could be to a certain extent migrated into the surface lattice of LNMO to generate a V-involved transition layer (Li-Ni-Mn-V-O surface solid solution), which greatly co-contributes to the enhanced electrochemical performances owning to the prominently depressed charge transfer resistance.