C-O Ring Construction: The Fuwa Synthesis of Exiguolide
Arjan W. Kleij of ICIQ optimized an aluminum catalyst for the conversion of the bis epoxide 1 to the oxetane 2 (ACS Catal. 2022, 12, 5464. ). A. Stephen K. Hashmi of Heidelberg University used a gold catalyst to rearrange the alkyne 3 to the oxetanone 4, that participated readily in Horner-Wadsworth-Emmons reactions (Org. Chem. Front. 2022, 9, 117. ).
Ting Li of Nanyang Normal University, Jun Zhu of Xiamen University and Liming Zhang of the University of California, Santa Barbara achieved high enantioselectivity in the rearrangment of the allyl alkynoate 5 to the lactone 6 (Org. Lett. 2022, 24, 4427. ). Qun Li and Yong Jian Zhang of Shanghai Jiao Tong University also observed high ee in the construction of the tetrahydrofuran 9 by the three-component coupling of the benzylidene malononitrile 7, the allene 8, and iodobenzene (Org. Lett. 2022, 24, 2081. ). Xue-Long Hou of the Shanghai Institute of Organic Chemistry assembled the dihydrofuran 12 by the combination of the enyne 10 with butadiene monoepoxide 11 (Org. Lett. 2022, 24, 1561. ). Yuan-Zhao Hua, Shi-Kun Jia and Min-Can Wang of Zhengzhou University used a dinuclear zinc catalyst to mediate the coupling of the enone 13 with the diol 14, leading to the dihydrofuran 15 (Org. Lett. 2022, 24, 3909. ).
Paul E. Floreancig of the University of Pittsburgh used electrolysis to drive the cyclization of the enol acetate 16 to the tetrahydropyranone 17 (Chem. Eur. J. 2022, 28, e202200335. ). Keisuke Asano of Hokkaido University and Seijiro Matsubara of Kyoto University employed a Cinchona-derived catalyst to mediate the cyclization of the enone 18 to the dihydropyran 19 (Tetrahedron 2021, 97, 132381. ). Francesco G. Gatti of the Politecnico di Milano showed that a combination of two enzymes reduced the enone 20 to the tetrahydropyran 21 (J. Org. Chem. 2022, 87, 6499. ). Janine Cossy of ESPCI Paris showed that the 2-iodoglycal 22 could be coupled with a range of Grignard reagents, as illustrated by the formation of the dihydropyran 23 (Chem. Eur. J. 2022, 28, e202104311. ).
Ian D. Williams and Guochen Jia of the Hong Kong University of Science and Technology developed a Re catalyst for the ring-closing metathesis of the diyne 24, leading to the macrolactone 25 (J. Am. Chem. Soc. 2022, 144, 6349. ). Shu-Li You, also of the Shanghai Institute of Organic Chemistry, achieved high enantiomeric excess in the Ir-mediated cyclization of the Z-allylic alcohol to the macrolactone 27 (J. Am. Chem. Soc. 2022, 144, 4770. ).
Exiguolide (30), isolated from the rare marine sponge Geodia exigua, showed potent anti-proliferative activity against human non-small cell lung cancer cell lines. In the course of a synthesis of 30, Haruhiko Fuwa of Chuo University cyclized the bromo alcohol 28 to the tetrahydropyran 29 (Angew. Chem. Int. Ed. 2022, 61, e202202549. ).