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Monday, February 20, 2023
Douglass F. Taber
University of Delaware

Enantioselective Construction of Alkylated Stereogenic Centers: The Bisai Synthesis of Lycoramine

Pher G. Andersson of Stockholm University showed that a Z/E mixture of the enone 1 could be hydrogenated to 2 in high ee (Nature Commun. 2022, 13, 361. ). Michael J. Krische of the University of Texas effected the enantioselective Tsuji reduction of the allylic carbonate 3, leading to the alkene 4 as a single diastereomer (J. Am. Chem. Soc. 2022, 144, 1016. ).

Houhua Li of Peking University used a diamine to direct the absolute course of the allylation of the unsaturated carboxylic acid 5, leading the disubstituted alkene 6 (Angew. Chem. Int. Ed. 2022, 61, e202116136. ). T. V. RajanBabu of the Ohio State University assembled the diene 8 by coupling the enol silyl ether 7 with ethylene (ACS Catal. 2022, 12, 5094. ). Eric Meggers of Philips-Universitšt Marburg used electrolysis to effect the coupling of the acyl imidazole 9 with the alkenyl borane 10, delivering 11 (J. Am. Chem. Soc. 2022, 144, 6964. ). Ming Shang of Shanghai Jiao Tong University showed that the Katritzky pyridinium salt 12 could be coupled with the terminal alkene 13 to give the amide 14 (J. Am. Chem. Soc. 2022, 144, 1130. ).

Zhongxing Huang of the University of Hong Kong reduced the prochiral diester 15 to the aldehyde 16 in high ee (J. Am. Chem. Soc. 2022, 144, 6918. ). Gen-Qiang Chen and Xumu Zhang of the Southern University of Science and Technology and Chi-Ming Che, also of the University of Hong Kong, used a gold catalyst to cyclize the diacid 17 to the lactone 18 (Angew. Chem. Int. Ed. 2022, 61, e202201739. ).

Bi-Jie Li of Tsinghua University coupled the alkyne 20 with the alkene 19, leading to the amide 21 (Angew. Chem. Int. Ed. 2022, 61, e202201099. ). Yangbin Liu of Shenzhen Bay Laboratory and Xiaoming Feng of Sichuan University effected the oxidative coupling of the β-ketoester 22 with the allylbenzene derivative 23, to give 24 (Angew. Chem. Int. Ed. 2022, 61, e202115715. ). Xueling Mi of Beijing Normal University used an enantiomerically-pure diamine to mediate the coupling of 22 with the alkyne 25, to deliver 26 (Org. Lett. 2022, 24, 1186. ). Stacey E. Brenner-Moyer of Rutgers/Newark found that a BINOL-derived phosphoric acid effectively directed the alkylation of the unsaturated aldehyde 27 with the allylic amine 28, leading, after hydrolysis, to 29 (J. Org. Chem. 2022, 87, 866. ).

Lycoramine (32), isolated from the red spider lily Lycoris radiata, is a potent acetylcholinesterase (AChE) inhibitor. Alakesh Bisai of the Indian Institute of Science Education and Research Kolkata established the cyclic quaternary center of 31 and thus 32 by Itsuno-Corey reduction of the cyclohexenone 30 followed by Johnson-Claisen rearrangement (J. Org. Chem. 2022, 87, 7786. ).

D. F. Taber, Org. Chem. Highlights 2023, February 20.