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Monday, July 26, 2021
Douglass F. Taber
University of Delaware

Arrays of Sterogenic Centers: The Inoue Synthesis of Hikizimycin

Chi-Ming Che of the University of Hong Kong designed an Fe catalyst that mediated the enantioselective dihydroxylation of the unsaturated ester 1, delivering the diol 2 (Angew. Chem. Int. Ed. 2020, 59, 16561. ). Eric Meggers of Philipps-Universitšt Marburg used a Ru catalyst to convert the N-acyloxy carbamate 3 to the cyclic carbamate 4 (Org. Lett. 2020, 22, 6653. ). Sukbok Chang of KAIST observed high regioselectivity in the formation of the cyclic carbamate 6 from the azidoformate 5 (J. Am. Chem. Soc. 2020, 142, 12324. ). Gen-Qiang Chen and Xumu Zhang of the Southern University of Science and Technology effected the dynamic kinetic reduction of the racemic α-keto β-lactam 7, leading to the β-lactam 8 in high ee (Chem. Commun. 2020, 56, 15557. ).

Weidi Cao and Xiaoming Feng of Sichuan University assembled the epoxide 12 by the triply-convergent coupling of the alkynyl ketone 9, the diazoacetate 10 and the nitrosoarene 11 (Org. Lett. 2020, 22, 6744. ). Harunobu Mitsunuma and Motomu Kanai of the University of Tokyo achieved high diastereoselectivity in the addition of commercial 2-butene (14) to citronellal (13) to give 15 (J. Am. Chem. Soc. 2020, 142, 12374. ). Hsyueh-Liang Wu of the National Taiwan Normal University prepared the homoallylic sulfonamide 18 by adding the potassium allyl trifluoroborate 17 to the imine 16 (Org. Lett. 2020, 22, 5675. ). Ming Chen of Auburn University used a chiral phosphoric acid to mediate the addtion of the bis-boronate 20 to the aldehyde 19, leading to 21 (Org. Lett. 2020, 22, 8967. ). K. A. Woerpel of New York University showed that the addition of trimethylaluminum to the readily-prepared seven-membered ring E alkene 22 and subsequent oxygenation both proceeded with high diastereoselectivity, delivering the alcohol 23 (Org. Lett. 2020, 22, 7518. ). Professor Feng and Xiaohua Liu, also of Sichuan University, assembled the α-quaternary amine 26 by adding the acyl imidazole 25 to the imine 24 (Nature Commun. 2020, 11, 3869. ).

Michael P. Doyle of the University of Texas at San Antonio showed that included water facilitated the opening of the silyl enol ether 27 (Metal-mediated Ring Construction: The Herzon Synthesis of Pleuromutilin 2017, December 11) with 28, leading to the Weinreb amide 29 (J. Org. Chem. 2020, 85, 9475. ). Weiqing Xie of Northwest A&F University showed that the photostimulated addition of aldehyde 19 to the enone 30 could be effectively mediated by a combination of a chiral phosphoric acid with a chiral imidazolidinone, leading to the flavonoid precursor 31 (Chem. Commun. 2020, 56, 10018. ).

Hikizimycin (35), isolated from a fermentation broth of Streptomyces A-5, was found to be a powerful antibiotic. A key step in the synthesis of 35 developed by Masayuki Inoue, also of the University of Tokyo, was the free radical coupling of 32 with 33, leading to 34 (J. Am. Chem. Soc. 2020, 142, 13227. ).

D. F. Taber, Org. Chem. Highlights 2021, July 26.