Reduction: The Dai Synthesis of Massarinolin A

Xiaobei Chen,Yanwei Hu and Shilei Zhang of Soochow University showed that the inexpensive calcium hydride could be used to reduce the aryl halide 1 to the arene 2 (Org. Chem. Front. 2021, 8, 4685. DOI: 10.1039/D1QO00758K). Kathrin Junge and Matthias Beller of the Leibniz-Institut für Katalyse showed that the water-gas shift reaction could be used to reduce the aryl bromide 3, leading to the deuterated arene 4 (Chem. Sci. 2021, 12, 14033. DOI: 10.1039/D1SC04259A). Hegui Gong of Shanghai University used a Ni catalyst to prepare 6 by the deoxygenation of the oxalate 5 (Synlett 2021, 31, 1625. DOI: 10.1055/a-1328-0352). Osvaldo Gutierrez, now at Texas A&M University, and Mark D. Levin of the University of Chicago used the reagent 8 to prepare 9 by the reductive deamination of 7 (J. Am. Chem. Soc. 2021, 143, 17366. DOI: 10.1021/jacs.1c09779).

Yan-Na Ma and Xuenian Chen of Zhengzhuo University demonstrated the convenience of KB₃H₈ as a reagent for organic synthesis, selectively reducing the keto aldehyde 10 to the keto alcohol 11 (Chem. Commun. 2021, 57, 12776. DOI: 10.1039/D1CC05638G). Chulbom Lee of Seoul National University demonstrated that the alkynoate of 12 could be selectively reduced to the aldehyde 13 in the presence of the two ketones (Angew. Chem. Int. Ed. 2021, 60, 22735. DOI: 10.1002/anie.202109193). Ya Kawamata and Phil S. Baran of Scripps-La Jolla used alternating current to reduce the imide of 14 to the lactam 15, leaving the aldehyde unchanged (J. Am. Chem. Soc. 2021, 143, 16580. DOI: 10.1021/jacs.1c06572). Stephen F. Martin of the University of Texas reduced and deprotected 16, leading to the tetrahydropyran 17 (Tetrahedron 2021, 89, 132150. DOI: 10.1016/j.tet.2021.132150).

J. Daniel Bailey of Takeda Pharmaceuticals and Bruce H. Lipshutz of the University of California, Santa Barbara demonstrated that using a surfactant, the water-soluble aldehyde bisulfite addition product 18 could be used directly in reductive amination with 19, leading to the amine 20 (Org. Lett. 2021, 23, 7205. DOI: 10.1021/acs.orglett.1c02604). Bao-Hua Xu of the Institute of Process Chemistry, Chinese Academy of Sciences showed that using a Ru catalyst, the nitroaromatic 21 could be coupled with the alcohol 22, leading to the amine 23 (Org. Chem. Front. 2021, 8, 6710. DOI: 10.1039/D1QO01269J). Xinxin Qi of Zhejiang Sci-Tech University and Xiao-Feng Wu, also of the Leibniz-Institut für Katalyse, coupled the enol triflate 24 with the nitroaromatic 21, leading to the amide 25 (Org. Chem. Front. 2021, 8, 6974. DOI: 10.1039/D1QO01508G). Sebastian C. Cosgrove of the University of Keele and the University of Manchester and Sabine L. Flitsch of the University of Manchester devised a flow system for the sequential application of otherwise incompatible enzyme systems, allowing the net coupling of the alcohol 26 with the amine 27 to give 28 (Angew. Chem. Int. Ed. 2021, 60, 18660. DOI: 10.1002/anie.202103805).

Massarinolin A (30), isolated from the aquatic fungus Massarina tunicata, showed activity against gram-positive bacteria. For the last step in their total synthesis, Mingji Dai of Purdue University used the Myers protocol to reduce the allylic alcohol 29 to 30 (Angew. Chem. Int. Ed. 2021, 60, 24828. DOI: 10.1002/anie.202109625).