Metal-Mediated C-C Ring Construction: The Chen/Zhang Synthesis of PGF_2α

Ilan Marek of Technion - Israel Institute of Science and Technology demonstrated that the homoallylic ether of the cyclopropene 1 was sufficient to direct the regioselectivity of the addition of the Grignard reagent 2 to give the cyclopropane 3 (Angew. Chem. Int. Ed. 2021, 60, 26368. DOI: 10.1002/anie.202111382). Naoya Kumagai and Masakatsu Shibasaki of BIKAKEN constructed the cyclopropane 6 by the enantioselective addition of the sulfonium ylide 5 to the unsaturated amide 4 (ACS Catal. 2021, 11, 11597. DOI: 10.1021/acscatal.1c02723).

Antonio M. Echavarren of ICIQ used a gold catalyst to mediate the addition of the alkynyl ether 8 to the alkene 7, leading to the cyclobutanone precursor 10 (Org. Lett. 2021, 23, 8989. DOI: 10.1021/acs.orglett.1c03499). Vincent N. G. Lindsay of North Carolina State University assembled the cyclobutanone 12 by adding the Grignard reagent 11 to the cyclopropanone generated in situ from the cyclopropyl sulfone 10, then brominating the product (Org. Lett. 2021, 23, 6482. DOI: 10.1021/acs.orglett.1c02303).

Jian-Hua Xie of Nankai University achieved high diastereoselectivity and enantioselectivity in the reduction of the racemic ketone 13 to the hydroxy ester 14 (Org. Lett. 2021, 23, 5153, DOI: 10.1021/acs.orglett.1c01689; 8883, DOI: 10.1021/acs.orglett.1c03384). Xing-Zhong Shu of Lanzhou University prepared the cyclopentane 17 by coupling the diene 15 with the bromoalkene 16 (J. Am. Chem. Soc. 2021, 143, 12961. DOI: 10.1021/jacs.1c05670).

Qiang Liu of Tsinghua University used a Co catalyst to isomerize the prochiral alkene 18 to the alcohol 19 (J. Am. Chem. Soc. 2021, 143, 20633. DOI: 10.1021/jacs.1c11343). Christopher Uyeda of Purdue University reduced 20 to the intermediate vinylidene (also termed "alkylidene") carbene, that inserted into the proximal alkenyl C-H bond to give the diene 21 (ACS Catal. 2021, 11, 14408. DOI: 10.1021/acscatal.1c03350). Wenbo Ye, Dingding Gao and Ping Tian of the Shanghai University of Traditional Chinese Medicine cyclized the prochiral cyclohexadienone 22 to the cyclohexenone 23 (Chem. Commun. 2021, 57, 9724. DOI: 10.1039/D1CC03645A). Takesi Yasui and Yoshihiko Yamamoto of Nagoya University cyclized the propiolate 24 to the tricyclic lactone 25 (Adv. Synth. Catal. 2021, 363, 4182, DOI: 10.1002/adsc.202100513; ACS Catal. 2021, 11, 9479, DOI: 10.1021/acscatal.1c02410).

Guo-Qiang Lin and Zhi-Tao He of the Shanghai Institute of Organic Chemistry developed a simple enantioselective route to the diester 26, that they subjected to Toste cyclization to give the bicyclic 27 (Nature Commun. 2021, 12, 5626. DOI: 10.1038/s41467-021-25978-6). Zhi-Xiang Yu of Peking University devised conditions for the transannular ene cyclization of the cyclooctenone 28 to the tricyclic alcohol 29 (Org. Lett. 2021, 23, 7566. DOI: 10.1021/acs.orglett.1c02766).

Gen-Qiang Chen and Xumu Zhang of the Southern University of Science and Technology established an efficient route to the prostaglandins, exemplified by PGF_2α (32), based on the enantioselective cyclization of the alkyne 30 to the diene 31 (Nature Chem. 2021, 13, 692. DOI: 10.1038/s41557-021-00706-1). The diene 31 should also allow ready access to the isoprostanes, endogenous mediators of inflammatory damage.