Cyclopropanes have been proved to be powerful synthetic building blocks. In particular the ring-opening reactions of donor-acceptor (D-A) cyclopropanes provide versatile access to a myriad of functionalized carbon skeletons.1 Among them, extensive study was mainly focused on the reactions of cyclopropane-1,1-dicarboxylates. In contrast, scant attention was paid to the reactions of cyclopropyl ketones which bear one or two carbonyl groups. In terms of nucleophiles initiated opening reactions, the asymmetric variation is rare that only one successful example on employing secondary aliphatic amines as nucleophiles has been achieved by Tang’s group.2 Other nucleophiles were not involved. Now we present our efforts to develop the asymmetric ring-opening of cyclopropyl ketones with amine, alcohol, thiophenol, carboxylic acid four different nucleophiles catalyzed by a chiral N,N'-dioxide/scandium(III) complex.3 Our strategy employed the two carbonyl groups of cyclopropyl ketones to coordinate to chiral metal complex for the discrimination of chirality. For primary amines, the carbonyl groups also served as a functional group for further intramolecular condensation. A series of 2,3-dihydropyrroles and γ-thio and γ-oxy carbonyl compounds were obtained in excellent yields and enantioselectivities. References 1) T. F. Schneider, J. Kaschel, D. B. Werz, Angew. Chem. Int. Ed. 2014, 53, 5504. 2) Y. Y. Zhou, L. J. Wang, J. Li, X. L. Sun, Y. Tang, J. Am. Chem. Soc. 2012, 134, 9066-9069; 3) (a) Y. Xia, X. H. Liu, H. F. Zheng, L. L. Lin, X. M. Feng, Angew. Chem. Int. Ed. 2015, 54, 227; (b) Y. Xia, L. L. Lin, F. Z. Chang, X. Fu, X. H. Liu, X. M. Feng, Angew. Chem. Int. Ed. 2015, DOI: 10.1002/anie.201506909

Asymmetric ring-opening of cyclopropyl ketones with nitrogen, oxygen, and sulfur-containing nucleophile

251st National Meeting (2016)

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