Intramolecular Cascade Cyclization of Cyclobutanone: Asymmetric Construction of Cyclobutanone Fused Oxa-Spirocycles
Shibaram Panda1, Nikhil Dipak Chavan1, Prasanta Ghorai1
1Department of Chemistry, Indian Institute of Science Education and Research (IISER) Bhopal, Bhopal By-pass Road, Bhauri, Bhopal 462066, India.
Abstract:
The successful implementation of a cascade reaction involving a cyclobutyl unit has posed a significant challenge in achieving ring-retentive functionalization because of the ring's sacrificial tendency. Herein, we have accomplished a cinchona-derived squaramide-catalyzed cascade reaction sequence, encompassing the desymmetrization of cyclobutanone, followed by an aldol reaction and, subsequently, a 1,4-addition step. This overall process offers a viable strategy to access architecturally fascinating oxa-spirocycles fused with cyclobutanone motifs in good yields with high optical purity.
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