Catalytic enantioselective reductive alkynylation of amides enables one-pot syntheses of pyrrolidine, piperidine and indolizidine alkaloids.

The primary objective in synthetic organic chemistry is to develop highly efficient, selective, and versatile synthetic methodologies, which are essential for discovering new drug candidates and agrochemicals. In this study, we present a unified strategy for a one-pot, catalytic enantioselective synthesis of α-alkyl and α,α'-dialkyl pyrrolidine, piperidine, and indolizidine alkaloids using readily available amides and alkynes. This synthesis is enabled by the identification and development of an Ir/Cu/N-PINAP catalyzed highly enantioselective and chemoselective reductive alkynylation of α-unbranched aliphatic amides, which serves as the key reaction. This reaction is combined with Pd-catalyzed tandem reactions in a one-pot approach, enabling the collective, catalytic enantioselective total syntheses of eight alkaloids and an anticancer antipode with 90-98% ee. The methodology's enantio-divergence is exemplified by the one-step access to either enantiomer of alkaloid bgugaine.

Application of pathological feature clustering in oral pathology teaching / 中华口腔医学杂志

To propose a new student-guided teaching method, in which students carried out the clustering of different diseases with the same pathological characteristics, and differentiated diagnosis of these diseases. This method was named pathological feature clustering (PFC). Seventy-seven undergraduates of School of Stomatology, Wuhan University were enrolled. Stratified random sampling method was adopted to divide the students into 4 groups with 18-20 students in each group. Each group of students selected a disease from the following four topics as the theme and summarize the histological characteristics of the disease: ①oral mucosal disease;②odontogenic tumors and tumor-like lesions, oral and maxillofacial cysts; ③salivary gland diseases;④epithelial-derived tumors and tumor-like lesions (referred to as topics 1, 2, 3, and 4, respectively). When discussing a specific type of disease, the group which select the topic was the summary group (SG), and the other groups were the non-summary group (NSG). After summarizing, students shared the summary results through PPTs, and teachers made comments and supplements. The teaching effect was evaluated by comparing the results of the pre-class test and the final examination. Students' acceptance of PFC teaching method was evaluated through a questionnaire, which included 8 objective questions and 1 subjective question. Likert-scale was used to design the questionnaire, with 1 to 5 points for each question. Students rated each question according to their own situation. Differences among groups were compared by Mann-Whitney U nonparametric test. The pre-class test results showed that the scores of students in SG group in subjects 1, 2, 3 [(5.6±0.8), 5.0(1.0) and (2.9±1.0) points for subjects 1, 2 and 3, respectively] were higher than those in NSG group [(5.1±1.0), 4.0(2.5) and 1.5(2.5) points] (U=402.50, P=0.047; U=392.00, P=0.026; U=295.00, P=0.003). The final examination results showed that there was no significant difference between the scores of the SG group and the NSG group in subjects 1, 2, 3 and 4 (P>0.05). These results showed that the differences between SG and NSG groups were reduced after the summarizing and share between groups, further demonstrating the effectiveness of the PFC teaching method. The results of questionnaire showed that 81.8%(63/77) students were completely satisfied with PFC teaching method, 13.0%(10/77) students were satisfied and 5.2%(4/77) students were basically satisfied. According to the feedback of Likert scale objective evaluation questionnaire, the mean score of each question ranged from 4.19 to 4.77, indicating that students believed that PFC teaching method had a positive impact on the learning of oral pathology. The PFC teaching method proposed in this study could improve the ability of pathological differential diagnosis of undergraduates.

Multicatalysis protocol enables direct and versatile enantioselective reductive transformations of secondary amides.

The catalytic asymmetric geminal bis-nucleophilic addition to nonreactive functional groups is a type of highly desirable yet challenging transformation in organic chemistry. Here, we report the first catalytic asymmetric reductive/deoxygenative alkynylation of secondary amides. The method is based on a multicatalysis strategy that merges iridium/copper relay catalysis with organocatalysis. A further combination with the palladium-catalyzed alkyne hydrogenation allows the one-pot enantioselective reductive alkylation of secondary amides. This versatile protocol allows the efficient synthesis of four types of α-branched chiral amines, which are prevalent structural motifs of active pharmaceutical ingredients. The protocol also features excellent enantioselectivity, chemoselectivity, and functional group tolerance to be compatible with more reactive functional groups such as ketone and aldehyde. The synthetic utility of the method was further demonstrated by the late-stage functionalization of two drug derivatives and the concise, first catalytic asymmetric approach to the κ-opioid antagonist aticaprant.