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ZnI2‑Catalyzed Diastereoselective [4 + 2] Cycloadditions of β,γ‑Unsaturated α‑Ketothioesters with Olefins

IR@IICB: CSIR-Indian Institute of Chemical Biology, Kolkata


Field	Value

Title	ZnI2‑Catalyzed Diastereoselective [4 + 2] Cycloadditions of β,γ‑Unsaturated α‑Ketothioesters with Olefins

Creator	Mal, Kanchan Das, Supriya Maiti, Nakul Chandra Natarajan, Ramalingam Das, Indrajit

Subject	Chemistry Structural Biology & Bioinformatics

Description	The potential of β,γ-unsaturated α-ketothioesters participating in hetero-Diels−Alder reaction has remained unexplored. We report herein the first study of a ZnI2-catalyzed highly diastereoselective inverse electron demand hetero-Diels−Alder reaction of β,γ-unsaturated α-ketothioesters with olefins to access highly substituted 3,4-dihydro-2H-pyrans. All the reactions proceed with cis-selectivity in moderate to excellent yields. Under similar reaction conditions, terminal alkynes undergo direct conjugate 1,4-addition to yield δ,ε-acetylenic α-ketothioesters. Furthermore, the utility of these cycloadducts has been demonstrated by an NBS-MeOH mediated stereospecific efficient access to fully substituted pyran rings. The product bromoethers undergo E2 elimination with DBU, resulting in substituted 3,6-dihydro-2H-pyrans. In addition, the thioester moiety of the products has been used for further transformations, such as amidations and Fukuyama coupling reactions.

Publisher	American Chemical Society

Date	2015

Type	Article PeerReviewed

Format	application/pdf

Identifier	http://www.eprints.iicb.res.in/2231/1/JOURNAL_OF_ORGANIC_CHEMISTRY__V_80___(_6_)2972%2D2988_;2015[40].pdf Mal, Kanchan and Das, Supriya and Maiti, Nakul Chandra and Natarajan, Ramalingam and Das, Indrajit (2015) ZnI2‑Catalyzed Diastereoselective [4 + 2] Cycloadditions of β,γ‑Unsaturated α‑Ketothioesters with Olefins. The Journal of Organic Chemistry, 80 (6). pp. 2972-2988.

Relation	http://dx.doi.org/10.1021/jo5024766 http://www.eprints.iicb.res.in/2231/