Synergistic [4 + 1] Spiroannulation and Selective Ring-Opening Strategy toward γ-Spirolactams
Imtiaj Mondal1, Koushik Naskar1, Shantonu Roy1
1Organic and Medicinal Chemistry Division, Indian Institute of Chemical Biology, 4, Raja S. C. Mullick Road, Jadavpur, Kolkata 700032, India.
Abstract:
A unique and propitious [4 + 1] spiroannulation of 2-aryl-4H-benzo[d][1,3]oxazine with maleimide has been delineated, furnishing diversely embellished γ-spirolactams featuring pendant benzyl alcohol via Rh(III)-catalyzed consecutive ring closing/ring opening followed by regioselective cleavage of the C4-O bond of 1,3-benzoxazine promoted by an in situ generated water maneuver constructing new C-C, C-N, and C-O bonds at a go. A detailed mechanistic study, including a thorough analysis of the incorporation of an extra oxygen source, has been showcased to make this strategy for structurally orchestrated isoindoline-1-one spirosuccinimides.
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