Organocatalyzed C-C Ring Construction: The Zhang Synthesis of Sinulochmodin C

Zheng Xiang of the Peking University Shenzhen Graduate School used a designer enzyme to mediate the addition of bromonitromethane 2 to the unsaturated aldehyde 1, leading to the nitro cyclopropane 3 (Angew. Chem. Int. Ed. 2024, 63, e202401635. DOI: 10.1002/anie.202401635). Hui Jin and Lixin Zhang of the Shenyang University of Chemical Technology reported a parallel investigation using a Cinchona-derived organocatalyst (Adv. Synth. Catal. 2024, 366, 2742. DOI: 10.1002/adsc.202400268). Janine Cossy of ESPCI Paris employed an ene-reductase to convert the cyclopropene 4 into the cyclopropane 5 (ACS Catal. 2024, 14, 6188. DOI: 10.1021/acscatal.4c00899).

Hualing He of Zhejiang Sci-Tech University effected the enantioselective reductive amination of the prochiral 1,3-cyclopentanedione 6 to the cyclopentanone 7 (Org. Lett. 2024, 26, 3951. DOI: 10.1021/acs.orglett.4c01195). Christoph Schneider of the Universität Leipzig used a BINOL-derived phosphoric acid to direct the oxa-Piancatelli rearrangement of the furan 8 to the cyclopentenone 9 (Chem. Commun. 2024, 60, 3063. DOI: 10.1039/D4CC00708E). Francesca Franco and Maurizio Benaglia of the Università degli Studi di Milano prepared the nitro alkene 10, then employed a Hayashi-Jørgensen amine to mediate the addition to cinnamaldehyde 11, leading to the cyclopentane 12 (Eur. J. Org. Chem. 2024, 27, e202301043. DOI: 10.1002/ejoc.202301043). Patrick Weber of the Graz University of Technology cyclized the carbohydrate-derived lactol 13 to the cyclopentane 14 (Helv. Chim. Acta 2024, 107, e202300219. DOI: 10.1002/hlca.202300219).

Lei Zhou of Sun Yat-Sen University asembled the cyclohexene 17 by the photochemically-promoted combination of the α-diazo ester 15 with the cyclopropylamine 16 (Org. Lett. 2024, 26, 3294. DOI: 10.1021/acs.orglett.4c00963). Hangmin Huang of the University of Science and Technology of China converted the unsaturated ester 18 into the cyclohexyl amine 19 by hydride abstraction followed by cyclization (Org. Chem. Front. 2024, 11, 864. DOI: 10.1039/D3QO01637D). Ying-Yeung Yeung of the Chinese University of Hong Kong developed a trialkylphosphonium oxoborate as an effective catalyst for the Diels-Alder cycloaddition of methacrolein 20 with isoprene 21 to give the cyclohexenecarboxaldehyde 22 (Chem. Asian J. 2024, 19, e202300981. DOI: 10.1002/asia.202300981). Rolf Breinbauer of the Graz University of Technology reduced the cyclohexadienone 23 to the cyclohexenone 24 (ACS Catal. 2024, 14, 7256. DOI: 10.1021/acscatal.4c00276).

Rambabu Chegondi of the Indian Institute of Chemical Technology used a Hayashi-Jørgensen amine to cyclize the prochiral cyclohexane-1,3-dione 25 to the bicyclic aldehyde 26 in high ee (Chem. Commun. 2024, 60, 3834. DOI: 10.1039/D4CC00487F). Manabu Hatano of Kobe Pharmaceutical University and Kazuaki Ishihara of Nagoya University used a BINOL-derived boronate to catalyze the Diels-Alder cyclization of the propynal 27 with cyclopentadiene 28, leading to the bicyclic aldehyde 29 in high ee (Org. Lett. 2024, 26, 3607. DOI: 10.1021/acs.orglett.4c01060).

Sinulochmodin C (32) was isolated from the soft coral Sinularia lochmodes. Hongbin Zhang of Yunnan University devised a route to 32 based on the guanidine-mediated double intramolecular Michael cyclization of the malonate 30 to the lactone 31 (Angew. Chem. Int. Ed. 2024, 63, e202315481. DOI: 10.1002/anie.202315481).