An enantioselective Biginelli reaction that proceeds by a dual-activation route has been developed by using a combined catalyst of a readily available trans-4-hydroxyproline-derived secondary amine and a Brønsted acid. Aromatic, heteroaromatic, and fused-ring aldehydes were found to be suitable substrates for this multicomponent reaction. The corresponding dihydropyrimidines were obtained in moderate-to-good yields with up to 98 % ee under mild conditions. Based on the experimental results and the observed absolute configurations of the products, a plausible transition state has been proposed to explain the origin of the activation and the asymmetric induction.

Summary Childhood obesity increases the risk of adulthood obesity and is associated with other adverse health outcomes later in life. It may be influenced by environmental characteristics of neighborhoods where children live, particularly dietary supply–related environmental factors. This study aimed to systematically review the evidence on the association between access to convenience stores and childhood obesity. We searched and filtered relevant literature in PubMed, Embase, Web of Science, and Cochrane Library published before 1 January 2019. Data on the basic characteristics of studies, measures of access to convenience stores, and associations of convenience stores with weight‐related behaviors and outcomes were extracted from 41 included studies. In general, the density of and proximity to convenience stores in children's residential and school neighborhoods were positively associated with unhealthy eating behaviors. However, their associations with children's weight status varied significantly by regions. The association between convenience store access and children's weight status was found to be negative in Canada, rather mixed in the United States and the United Kingdom, and not significant in East Asia. We suggest future research to clearly define the convenience store, better measure the access to convenience store, and also measure children's journey and food purchasing and consumption behaviors, to explain pathways from convenience store access to childhood obesity for designing effective interventions and policies.

Summary Childhood obesity is one of the most pressing public health issues nowadays. The environmental factors have been identified as potential risks for obesity, as they may influence people's lifestyle behaviours. Lack of access to supermarkets that usually provide healthy food options has been found to be a risk factor for childhood obesity in several studies. However, findings remained inconclusive. We aimed to systematically review the association between access to supermarkets and childhood obesity. A literature search was conducted in the Cochrane Library, PubMed, Web of Science, and Embase for studies published before 1 January 2019. Twenty‐four studies conducted in four countries were identified, from which data on the basic characteristics of studies and participants, measures of access to supermarkets, and associations between access to supermarkets and weight‐related behaviours and outcomes were extracted. The median sample size was 1858 participants. Half of the included studies indicated a negative association, one fourth reported a positive association, and the remaining one fourth did not find a significant association. Better designed studies are necessary to achieve a robust understanding of this epidemiological relationship in the future.

Chiral a-hydroxy phosphonates and phosphonic acids are widely applied in the pharmaceutical industry owing to their biological activity, [1] and intense efforts have been made on the asymmetric hydrophosphonylation of aldehydes. To our knowledge, the first highly enantioselective hydrophosphonylation was realized by the Shibasaki group using heterobimetallic complexes ([LaLi 3 (binaphthoxide) 3 ], [AlLi(binaphthoxide) 2 ]) as tailor-made catalysts.[2] Recently, Kee and co-workers studied the catalytic performance of chiral [Al(salcyen)] and [Al(salcyan)] complexes.[3] Subsequently, the Katsuki group developed an interesting and highly efficient C 1 -symmetric [Al(salalen)] complex for the reaction.[4] An aluminum-binaphthyl Schiff base complex was also found to be effective for the reaction.[5] Although a number of works have appeared on the synthesis of chiral a-hydroxy phosphonates, [6] searching for a catalyst system that could achieve high reactivity and enantioselectivity is still challenging and interesting. As excellent chiral scaffolds, tridentate Schiff base metal complexes, especially those of vanadium, chromium, and iron, have successfully been applied in many asymmetric reactions.[7] Herein, we present a highly efficient asymmetric hydrophosphonylation of various aldehydes catalyzed by chiral tridentate Schiff base Al III complexes. Initially, tridentate Schiff base 1 a (Scheme 1), derived from l-valinol and 3,5-di-tert-butylsalicylaldehyde, reacted in situ with various aluminum(III) reagents to form complexes that catalyze the asymmetric hydrophosphonylation (Table 1, entries 1-3). The counterions of 1 a-Al III complexes showed a decisive effect on the enantioselectivity. [3a, 8] Complex 1 aEt 2 AlCl catalyzed the reaction smoothly, giving the desired products with 86 % ee, while only a racemate product was obtained in the presence of 1 a-AlEt 3 (Table 1, entry 1 vs. 3). It was interesting that catalyst 1 a-Al(OiPr) 3 showed an opposite absolute sense of stereoinduction (Table 1, entry 2). The disparate results were probably caused by the different steric and electronic properties of the counterions (Cl, Et, and OiPr), which each exhibited a different action in the catalytic cycle. [9b,d] To further improve the enantioselectivity of the reaction, [9a] the steric and electronic effects based on 1 were examined (Table 1, entries 1 and 4-8). As shown in Table 1, electron-donating groups at the position para to the OH Scheme 1. Chiral ligands used in the study. Ad = adamantyl. ee [%][c]