Organic Chemistry Portal
Organic Chemistry Highlights

Monday, December 11, 2023
Douglass F. Taber
University of Delaware

Metal-Mediated C-C Ring Construction: The Li Synthesis of Bufogargarizin A

Christopher Uyeda of Purdue University achieved high enantioselectivity in the cyclopropanation of myrcene (1) with 2,2-dichloropropane (2) to give 3 (J. Am. Chem. Soc. 2023, 145, 9441. DOI: 10.1021/jacs.3c01949). Qinglei Chong and Fanke Meng of the Shanghai Institute of Organic Chemistry assembled the cyclobutane 6 by conjugate addition of the cyclopropylcarbinol 5 to the cyclobutene ester 4 (J. Am. Chem. Soc. 2023, 145, 3588. DOI: 10.1021/jacs.2c12475).

Junfeng Yang and Junliang Zhang of Fudan University used electrolysis to cyclize the enyne 7 to the cyclopentane 8 (Nature Commun. 2023, 14, 1301. DOI: 10.1038/s41467-023-36704-9). P. Andrew Evans of Queens University developed the Rh-catalysed Pauson-Khand cyclization of the chloroacetylene 9, leading to the cyclopentenone 10 (Angew. Chem. Int. Ed. 2023, 62, e202300211. DOI: 10.1002/anie.202300211). Marcus A. Tius of the University of Hawaii effected the Nazarov cyclization of the α-diketone 11 to give 12 with high diastereoselectivity (Org. Biomol. Chem. 2023, 21, 5014. DOI: 10.1039/D3OB00735A). Quan Cai, also of Fudan University, carried out the Diels-Alder cycloaddition of the alkenyl selenide 14 to the 2-pyrone 13, leading, after reduction and acid-mediated rearrangement, to the lactone 15 (Synlett 2023, 34, 948. DOI: 10.1055/a-1990-5276).

Xiaohua Liu and Xiaoming Feng of Sichuan University prepared the keto nitrile 17 by enantioselective conjugate addition of cyanide to the doubly-activated cyclohexenone 16 (ACS Catal. 2023, 13, 877. DOI: 10.1021/acscatal.2c05509). Huw M. L. Davies of Emory University coupled the diazo ester 19 with the protected cyclohexylamine 18 to give 20 with high regio-, enantio- and diastereoselectivity (Org. Lett. 2023, 25, 3995. DOI: 10.1021/acs.orglett.3c00844). Professor Zhang and Zhiming Li, also of Fudan University, and Yuanjing Xiao of East China Normal University prepared the cyclohexene 23 by coupling the cyclohexadiene 21 with the iodoarene 22 (Angew. Chem. Int. Ed. 2023, 62, e202215407. DOI: 10.1002/anie.202215407). Twenty-five years ago, Fumie Sato of the Tokyo Institute of Technology showed that the easily-prepared silyl ether 24 could readily be converted to either enantiomer of the 5-alkyl cyclohexenone 25 (Angew. Chem. Int. Ed. 1998, 37, 2099. DOI: 10.1002/(SICI)1521-3773(19980817)37:15<2099::AID-ANIE2099>3.0.CO;2-U).

Paola Nava and Gaėlle Chouraqui of Aix Marseille University used the diazo ester 26 to cyclopropanate the protected cyclopropylcarbinol 27, then heated the product, leading to the cyclooctadiene 28 (Adv. Synth. Catal. 2023, 365, 1002. DOI: 10.1002/adsc.202300015). Yang Li, Qing Sun and Jin-Heng Li of Nanchang Hangkong University constructed the lactam 31 by the three-component coupling of the enyne 29, the aniline 30 and carbon monoxide (Org. Lett. 2023, 25, 4303. DOI: ). Giovanni Maestri of the Universitą di Parma reported a parallel investigation (Angew. Chem. Int. Ed. 2023, 62, e202216817. DOI: 10.1002/anie.202216817).

Bufogargarizin A (34) was isolated from the venom of the Asiatic toad Bufo bufo gargarizins, long used in traditional Chinese medicine. Chuang-Chuang Li of the Southern University of Science and Technology assembled the carbocyclic core of 34 by the cyclization of the alkyne 32 to the cycloheptenone 33 (J. Am. Chem. Soc. 2023, 145, 2098. DOI: 10.1021/jacs.2c13494).

D. F. Taber, Org. Chem. Highlights 2023, December 11.