Metal-Mediated C-C Ring Construction: The Liu/Qin Synthesis of Garryine

John F. Hartwig of the University of California, Berkeley showed that an Ir-containing mutant cytochrome mediated the enantioselective addition of ethyl diazoacetate 2 to the allene 1, leading to the alkylidene cyclopropane 3 (J. Am. Chem. Soc. 2024, 146, 1819. DOI: 10.1021/jacs.3c13011). Ping Lu of Fudan University effected the enantioselective conjugate reduction of the cyclobutenone 4 to give the cyclobutanone 5 (Angew. Chem. Int. Ed. 2024, 63, e202400515. DOI: 10.1002/anie.202400515).

Liming Zhang of the University of California, Santa Barbara assembled the cyclopentenone 7 by the cyclization of the propargyl carbonate 6 followed by enantioselective protonation (J. Am. Chem. Soc. 2024, 146, 3598. DOI: 10.1021/jacs.3c11919). Ken Tanaka of the Tokyo University of Technology combined the alkyne 8 with the methacrylamide 9 to prepare the cyclopentane 10 (ACS Catal. 2024, 14, 4951. DOI: 10.1021/acscatal.4c00572). Wenhao Yu and Peng Cao of Sichuan Normal University reacted the cyclobutanol 11 with the allylic alcohol 12, leading to the cyclopentanone 13 (Org. Lett. 2024, 26, 1224. DOI: 10.1021/acs.orglett.4c00025). Pei Tang of Sichuan University and Fen-Er Chen of Fudan University cyclized the enyne 14 to the methylidene cyclopentane 15 (Org. Lett. 2024, 26, 4818. DOI: 10.1021/acs.orglett.4c01669).

Pher G. Andersson of Stockholm University selectively hydrogenated the diene 16 to the cyclohexenone 17 (Chem. Eur. J. 2024, 30, e202303406. DOI: 10.1002/chem.202303406). Jialin Ming and Shufeng Chen of Inner Mongolia University added phenylboronic acid under equilibrating conditions to the cyclohexenone 18, leading to the ester 19 in high ee (Org. Lett. 2024, 26, 1364. DOI: 10.1021/acs.orglett.3c04281). Yin Tian of the Chengdu University of Traditional Chinese Medicine and Ming-Sheng Xie and Hai-Ming Guo of Hunan Normal University uncovered a nickel catalyst that mediated the enantioselective Diels-Alder cycloaddition of styrene 21 to the 2-pyrone 20 to give the cyclohexene 21 (ACS Catal. 2024, 14, 8930. DOI: 10.1021/acscatal.4c02072). Chao Zheng of the Shanghai Institute of Organic Chemistry and Quan Cai of Fudan University reported a parallel investigation, constructing the cyclohexadiene 23 by the combination of the 2-pyrone 20 with the diene 22 (J. Am. Chem. Soc. 2024, 146, 6936. DOI: 10.1021/jacs.3c14409).

Zhiguo Zhang, Nana Ma and Guisheng Zhang of Henan Normal University rearranged the vinyl cyclopropane 24 to the cycloheptenone 25 (J. Org. Chem. 2024, 89, 1127. DOI: 10.1021/acs.joc.3c02319). Richmond Sarpong of the University of California, Berkeley reported the Pd-mediated ring opening of the carvone-derived cyclobutanol 26 and subsequent intramolecular Heck addition, leading after β-hydride elimination to the α-methylene ketone 27 (Angew. Chem. Int. Ed. 2024, 63, e202317348. DOI: 10.1002/anie.202317348).

The pentacyclic alkaloid garryine (30) was isolated from the bark of the canyon silktassel Garrya veatchii Kellogg of Southern California. En route to 30, Xiao-Yu Liu and Yong Qin of Sichuan University established the absolute configuration of the tricyclic precursor 29 by the enantioselective intramolecular Heck cyclization of the diene 28 (J. Am. Chem. Soc. 2024, 146, 1081. DOI: 10.1021/jacs.3c12171).