2026-10-14T02:27:52Z https://api.figshare.com/v2/oai

oai:figshare.com:article/34027530 2026-09-29T20:04:31Z category_1 category_4 category_12 category_14 category_15 category_16 category_21 category_873 category_61 category_132 portal_63 item_type_6 month_year_09_2026

Highly Stereoselective Reaction of Bicyclo[1.1.0]butanes and Isatins Chengzhuo Wang (18398331) Weimeng Ma (25138794) Jiaxi Xu (681245) Biophysics Biochemistry Cell Biology Molecular Biology Neuroscience Physiology Biotechnology Chemical Sciences not elsewhere classified Developmental Biology Infectious Diseases substantial steric hindrance representative cyclic ketones otf )< sub opening activation strategy key carbocation intermediates ketonic carbonyl group ketones remains elusive functionalized heterocyclic scaffolds baylis – hillman amidic carbonyl moiety observed high diastereoselectivity yl )- 3 3 -( cyclobuten highly stereoselective reaction excellent diastereoselectivity type ring synthetic utility protocol provides primary origin poor electrophilicity isatins stabilizes isatin derivatives facilitating scale efficient avenue control experiments catalyzed reaction Bicyclo[1.1.0]butanes (BCBs) have emerged as versatile strained building blocks for constructing stereodefined cyclic scaffolds. However, the Lewis-acid-catalyzed reaction of BCBs and ketones remains elusive, hampered by the poor electrophilicity and substantial steric hindrance of the ketonic carbonyl group. The La(OTf)₃-catalyzed reaction of BCBs and isatins achieved highly stereoselective synthesis of 3-(cyclobuten-3-yl)-3-hydroxyindolin-2-ones in up to 97% yield with excellent diastereoselectivity (dr of >20:1). Control experiments and density functional theory calculations corroborate the reaction as a Baylis–Hillman-type ring-opening activation strategy with isatin derivatives as representative cyclic ketones, revealing that the amidic carbonyl moiety of isatins stabilizes the key carbocation intermediates, which is the primary origin of the observed high diastereoselectivity. Notably, partial products precipitate spontaneously and can be isolated via simple filtration without tedious column chromatography, facilitating scale-up preparation. This protocol provides an efficient avenue to functionalized heterocyclic scaffolds and expands the synthetic utility of BCBs. 2026-09-29T00:00:00Z Text Journal contribution 10.1021/acs.joc.6c01677.s002 https://figshare.com/articles/journal_contribution/Highly_Stereoselective_Reaction_of_Bicyclo_1_1_0_butanes_and_Isatins/34027530 CC BY-NC 4.0