Organometallic C-C Ring Construction: The Nishikawa/Morimoto Synthesis of Toxicodenane A
Xihe Bi of Northeast Normal University showed that the diazo alkane generated in situ from the sulfonylhydrazide 2 could with a silver catalyst be added to the alkene 1, to give the cyclopropane 3 (Chem. Commun. 2022, 58, 3485. ). Matthew J. Gaunt of the University of Cambridge effected enantioselective metalation of the prochiral amine 4, leading to the cyclopropane 5 (J. Am. Chem. Soc. 2022, 144, 3939. ).
Stephen P. Fletcher of the University of Oxford achieved high enantioselectivity in the coupling of the prochiral cyclobutene 6 with salicylaldehyde 7 to give the cyclobutane 8 (Chem. Sci. 2022, 13, 236, ; Chem. Sci. 2022, 13, 1177, ). Thorsten Bach of the Technische Universität München used a Rh catalyst to direct the photocyclization of the α-alkoxy enone 9 to the cyclobutane 10 (Chem. Sci. 2022, 13, 2378. ).
Pei Tang of Sichuan University and Fener Chen of Fudan University employed stoichiometric SmI2 to cyclize the aldehyde 11 to the alcohol 12 (Chem. Commun. 2022, 58, 6000. ). Alberto Fraile and José Aleman of the Universidad Autónoma de Madrid assembled the amine 15 by coupling the acyl imidazole 13 with the cyclopropyl amine 14 (Chem. Commun. 2022, 58, 1334. ).
Aaron Aponik of the University of Florida coupled the racemic acid 16 with the allylic chloride 17, leading to the cyclohexanone 18 in high ee (ACS Catal. 2022, 11, 14842. ). Thomas E. La Cruz of Bristol Myers Squibb also achieved high ee in the conversion of the prochiral bis-benzoate 19 to the protected cyclohexyl amine 20 (J. Org. Chem. 2022, 87, 1996. ). Kazuaki Ishihara of Nagoya University developed a Cu catalyst that mediated the Diels-Alder cycloaddition of the acyl pyrazole 21 with isoprene 22, leading to the ester 23 (Synlett 2022, 33, 585. ). Alireza Ariafard of the University of Tasmania and Philip Wai Hong Chan of Monash University used a gold catalyst to mediate the coupling of the diyne 24 with nitrosobenzene 25, leading to the cyclohexene 26 (ACS Catal. 2022, 12, 7288. ).
Dirk M. Guldi of Friedrich-Alexander-Universität Erlangen-Nürnberg and Frank Glorius of the Westfälische Wilhelms-Universität Münster effected the ring expansion of the cyclopentanone 27 to the cycloheptanone 28 (Angew. Chem. Int. Ed. 2022, 61, e202112695. ). Chang Ho Oh of Hanyang University used Cu(OTf)2 to catalyze the conversion of the enyne 29 to the tricyclic ketone 30 (Synlett 2022, 33, 983. ).
Toxicodenane A (33), isolated from the dried resin of the lacquer tree Toxicodendron vernicifluum, showed some protective activity against lipid-induced toxicity in cultured renal proximal tubular cells. Keisuke Nishikawa and Yoshiki Morimoto of Osaka City University established the cycloheptane ring of 33 by the Barbier-type cyclization of the keto sulfone 31 to the tertiary alcohol 32 (Org. Lett. 2022, 24, 531. ).